HHE Report No. HETA-2000-0268-2812, Southwest Airlines ... · HETA 2000-0268-2812 Southwest...

HETA 2000-0268-2812Southwest Airlines San Antonio Reservations Center

San Antonio, Texas

Kristin K. Gwin, M.S.Richard J. Driscoll, Ph.D.

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports



This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.


applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

http://www.cdc.gov/niosh/hhe/reports



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PREFACEThe Hazard Evaluations and Technical Assistance Branch (HETAB) of the National Institute forOccupational Safety and Health (NIOSH) conducts field investigations of possible health hazards in theworkplace. These investigations are conducted under the authority of Section 20(a)(6) of the OccupationalSafety and Health (OSHA) Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary of Health andHuman Services, following a written request from any employer or authorized representative of employees,to determine whether any substance normally found in the place of employment has potentially toxic effectsin such concentrations as used or found.

HETAB also provides, upon request, technical and consultative assistance to Federal, State, and localagencies; labor; industry; and other groups or individuals to control occupational health hazards and toprevent related trauma and disease. Mention of company names or products does not constitute endorsementby NIOSH.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORTThis report was prepared by Kristin K. Gwin and Richard J. Driscoll of HETAB, Division of Surveillance,Hazard Evaluations and Field Studies. Field assistance was provided by Gregory A. Burr. Analyticalsupport was provided by P&K Microbiology Services, Inc. Desktop publishing was performed by RobinSmith. Review and preparation for printing were performed by Penny Arthur.

Copies of this report have been sent to employee and management representatives at Southwest Airlines andthe OSHA Regional Office. This report is not copyrighted and may be freely reproduced. Single copies ofthis report will be available for a period of three years from the date of this report. To expedite your request,include a self-addressed mailing label along with your written request to:

NIOSH Publications Office4676 Columbia ParkwayCincinnati, Ohio 45226

800-356-4674

After this time, copies may be purchased from the National Technical Information Service (NTIS) at5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may beobtained from the NIOSH Publications Office at the Cincinnati address.

For the purpose of informing affected employees, copies of this report shall beposted by the employer in a prominent place accessible to the employees for aperiod of 30 calendar days.

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Highlights of the NIOSH Health Hazard Evaluation

Evaluation of Indoor Air Quality at the San Antonio Reservations Center

In June 2000, NIOSH investigators conducted a health hazard evaluation at Southwest Airline’s San Antonio ReservationsCenter (SRC). We assisted OSHA in evaluating indoor air quality, ventilation, and health symptoms at the reservations center.

What NIOSH Did

# We made a visual inspection of the building’s interiorand exterior, and the ventilation system.

# We took bulk insulation samples from interiorinsulation in a supply duct, bulk dust samples fromcarpeted areas, and tape samples from beneathrestroom sinks to look for microbial growth.

# We collected temperature, relative humidity, andcarbon dioxide measurements, checked for moisture inthe walls and floor, and looked for mold between thewalls of quadrant A and B using a boroscope.

# We made airflow measurements to see if areas weremaintained under positive, negative, or neutralpressures.

# We talked with some employees about their symptomsand health concerns.

What NIOSH Found

# We saw only limited evidence of microbial growthduring inspection of the building (beneath restroomsinks).

# One bulk dust sample from a carpeted wall in quadrantB showed increased fungal concentrations whencompared to the other samples. Two of the five tapesamples from beneath the sinks in the restroom showedfungal growth.

# Average temperatures in the SRC were within therecommended summer comfort range (73°-79°F), withthe exception of a few areas which varied by only 1°-2°F.

# Average relative humidity within the SRC waswithinthe recommended comfort range (30%-60%).

# Carbon dioxide measurements were well below 800ppm, indicating an adequate amount of outdoor air isbeing supplied.

# Allergy-like symptoms were reported by workers;however, it did not appear that the symptoms wererelated to exposures unique to the workplace.

What Southwest Airlines ManagersCan Do

# Replace the carpeting on the walls of the quadrantswith a non-carpeted, acoustical material that will beeasier to keep clean and to dry when water leaks occur.

# If an alternative acoustical material is not used on thewalls, then the new carpet should be HEPA-vacuumedon a weekly basis to prevent buildup of dust and debris.

# Replace the moldy plywood beneath the sinks in therestrooms.

# Prior to any renovation, controls should be instituted toprotect both the workers and the adjacent environment(see full report for further details.)

# Water leaks should be fixed immediately, and water-damaged materials either dried (within 24-48 hours)and properly cleaned, or replaced (see full report forfurther details).

What the Southwest Airlines Employees Can Do

# Employees with health concerns should see their healthcare provider to determine the cause and propertreatment.

CDCCENTERS FOR DISEASE CONTROL

AND PREVENTION

What To Do For More Information:We encourage you to read the full report. If you would

like a copy, either ask your health and safetyrepresentative to make you a copy or call

1-513/841-4252 and ask for HETA Report # 2000-0268-2812

Highlights of the HHE Report

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Health Hazard Evaluation Report 2000-0268-2812Southwest Airlines San Antonio Reservations Center

San Antonio, TexasNovember 2000

Kristin K. Gwin, M.S.Richard J. Driscoll, Ph.D.

SUMMARYIn April 2000, the National Institute for Occupational Safety and Health (NIOSH) received a request fromthe Occupational Safety and Health Administration (OSHA) for assistance in the evaluation of potentialmicrobial contamination in the Southwest Airlines San Antonio Reservations Center (SRC), San Antonio,Texas. A similar request had been previously received by NIOSH from Southwest Airlines management.Employees in the SRC believed their health problems, which included upper respiratory infections, asthma,fatigue, headaches, chemical sensitivity, and loss of concentration and short-term memory, were related toworking in this building.

On June 28-30, 2000, NIOSH investigators conducted a site visit at the reservations center. A walk-throughinspection was made of the building interior, exterior, and roof. Bulk material samples were collected frominterior insulation in a supply duct above quadrant A, and bulk dust samples were collected on carpeted areasto assess microbial contamination. Surface samples using sticky tape were also collected beneath sinks ina women’s restroom. Measurements to detect moisture incursion and general indoor air quality comfortparameters were collected, and a qualitative ventilation assessment was also performed. Confidentialmedical interviews were conducted to assess health concerns.

Fungal concentrations from two bulk material samples of interior insulation in the supply duct abovequadrant A ranged from less than the detectable limit (<758 colony forming units per gram of material[CFU/g]) to 7.1x104 CFU/g. Cladosporium cladosporioides was the fungi detected. Bacterial concentrationsfrom the two bulk insulation samples were not detected (ND) (<758 CFU/g in one sample and <893 CFU/gin the other). Bulk dust samples yielded fungal levels ranging from 1.4x103 to 1.45x105 CFU/g. Pencillium,Acremonium, Cladosporium, and Alternaria alternata were the predominant fungi identified. One of the sixbulk dust samples revealed increased fungal concentrations of Penicillium when compared with the othersamples. Dust characterization showed samples consisted mainly of mineral crystals, skin flakes, andcellulose fibers. Sticky tape samples taken beneath the sinks in the women’s restroom (closest to the breakroom) revealed mostly wood fibers with paint. However, fungal growth was observed in two of the fivesamples. This indicates that microbial growth is present.

Temperatures were within the range recommended by the American Society of Heating, Refrigeration, andAir-conditioning Engineers (ASHRAE), with the exception of a few areas which varied by only 1°- 2°Fabove or below the recommended range (73°-79°F). Relative humidity measurements were also within therange recommended by ASHRAE; however, almost half of the measurements closely approached the

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recommended upper limit. All carbon dioxide measurements were well below 800 parts per million (ppm),a level indicating an adequate amount of outdoor air is being supplied to the quadrant and office areas.

Confidential interviews were conducted with 13 employees to assess their symptoms and health concerns.The most common symptoms reported by the employees were itchy watery eyes, runny nose, chronic sinusinfections, headaches, and fatigue.

Based on the information and measurements obtained during this Health Hazard Evaluation, NIOSHinvestigators conclude that a health hazard was not present at the time of the site visit, and that there islimited evidence of the presence of microbial growth in the SRC. There was no evidence that the healthproblems reported by employees were, on the whole, related to an exposure unique to the work environment.Recommendations addressing the carpet on the quadrant walls, the humidity levels, housekeepingprocedures, and future water incursion incidents are included in the report.

Keywords: SIC 4729 (Arrangement of Passenger Transportation, Not Elsewhere Classified), airlinereservations center, indoor air quality, microbial contamination, Penicillium, Cladosporium, Acremonium,asthma.

TABLE OF CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Acknowledgments and Availability of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Highlights of the NIOSH Health Hazard Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Building Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Ventilation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Prior Building Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Industrial Hygiene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Penicillium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Temperature and Relative Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Industrial Hygiene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Bulk Sample Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Comfort Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Discussion and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Health Hazard Evaluation Report No. 2000-0268-2812 Page 1

INTRODUCTION

In April, 1999, the National Institute forOccupational Safety and Health (NIOSH)received a request from the Austin Area Office ofthe Occupational Safety and HealthAdministration (OSHA) for help in the evaluationof potential microbial contamination in theSouthwest Airlines San Antonio ReservationsCenter (SRC), San Antonio, Texas. A similarrequest from Southwest Airlines management wasreceived by NIOSH a few weeks earlier.Employee health concerns included upperrespiratory infections, asthma, fatigue, headaches,chemical sensitivity, and loss of concentration andshort-term memory.

On June 28-30, 2000, NIOSH investigators(including two industrial hygienists and anepidemiologist) conducted a site visit to theSouthwest Airlines SRC. An opening conferencewas held with building management, the facilitymaintenance specialist, International Associationof Machinists and Aerospace Workers (IAM)union stewards, Southwest Airlines CorporateCounsel, and an industrial hygienist from theAustin area office of OSHA. Information wasobtained relating to the building and the history ofthe concerns involving microbial contamination.A walk-through inspection was made of thebuilding interior and exterior. Attention wasfocused on the four quadrants where customersales representatives work, and the heating,ventilating, and air-conditioning (HVAC) unitslocated in mechanical rooms. Bulk material anddust samples were collected from interiorinsulation in a supply duct above quadrant A andon carpeted areas to assess microbialcontamination. Sticky tape surface samples werecollected from beneath sinks in a women’srestroom. Measurements to detect moistureincursion and general indoor air quality comfortparameters were also collected. Confidentialinterviews were conducted with employees todetermine the extent of their health concerns andto determine whether symptoms were consistent

with work place exposures. A closing conferencewas held on June 30, 2000, during whichpreliminary findings and recommendations werediscussed.

BACKGROUND

Building DescriptionThe Southwest Airlines SRC is a one-story brickstructure with approximately 31,000 square feet(ft2) of indoor floor space. The building, which isowned by Southwest Airlines, has been used as areservations center since it was built in 1981. It isoccupied 24 hours a day, 7 days per week withvariable work shifts. There are approximately 617employees at the reservations center. Buildingoccupancy varies daily depending on work loadand overtime. During the 2-day NIOSH site visit,the average daily occupancy was approximately185 employees.

The work stations of the reservations agents arearranged concentrically and divided into fourquadrants, A-D (see figure 1). There are six toseven rows of workstations in each quadrant.Workstations are separated by connecting,carpeted cubicle dividers approximately four feetin height. At the center of the quadrants is aconsole area where supervisors work. There is agradual incline in the floor, extending from theconsole up to the back of each quadrant. Thecubicles are equipped with video display terminalsand keyboards, and are occupied by the customersales or customer care representatives. Themajority of enclosed offices, the break room, andthe training room are located in the area behindquadrant D. Six enclosed offices and aconference room are located behind quadrant C.The entire building is carpeted, with the exceptionof the break room and the restrooms. The walls ineach quadrant are also carpeted for acousticalattenuation. This carpeting was replaced duringthe summer of 1995. Pesticides are sprayedaround the interior and exterior of the building ona monthly basis.

Health Hazard Evaluation Report No. 2000-0268-2812

Ventilation System A designated indoor smoking area is locatedadjacent to the break room. It is segregated bywalls and two doors, one leading to the breakroom and one leading into a perimeter hallway.This smoking area is ventilated by an exhaust fanthat exhausts the air directly outside, thuspreventing it from mixing with return air fromother areas of the building and being dispersedinto the rest of the reservations center. OneTrane® HVAC unit in the mechanical roombehind quadrant D services this room, the non-smoking portion of the break room, and thetraining room. An electrostatic precipitator aircleaner was mounted on the ceiling of the roomapproximately one year ago. Filters in the aircleaner are replaced monthly.

The remaining ventilation systems at the SRCconsist of six large Trane® HVAC units housed infour mechanical rooms. One Trane® unit isdedicated to servicing each individual quadrant,and the remaining two service the smoking andnon-smoking break rooms, training room, and themain offices. However, the air is mixed,recirculated, and returned through ducts in thearea above the drop ceiling. This allows formixing of air throughout all areas of the building(except the designated smoking room). Fouroutdoor air (OA) intakes and six exhaust fans arelocated on the roof of the building. Two of theexhaust fans are dedicated to the restrooms andare located at least 25 feet from the OA intakes.The temperature and amount of OA introducedinto the building is regulated using electronicallycontrolled fan-powered variable- or constant air-volume box dampers. The former is utilized inoffice areas and the latter is utilized in thequadrants. Carbon dioxide (CO2) sensors, with a1,000 part per million (ppm) set-point, control theOA intake dampers based on the levels of CO2detected within the building. When CO2 levelsrise, a greater amount of OA is brought into thebuilding. The ventilation consultant reported that,on average, between 10%-20% of OA is broughtinto the building. OA enters the mechanical

rooms housing the AHU and mixes with the air inthe room before it enters the AHU. Filtrationutilized prior to air entering the AHUs consists ofa 30% efficient, 2" pleated pre-filter and a 65%efficient secondary filter. The pre-filters arereplaced monthly basis and the secondary filtersare replaced quarterly. Two water chillersprovide a chilled-water cooling system. Thedischarge water temperature is electronicallymaintained at 44-45°F. After the air isdehumidified, terminal electric re-heaters warmthe supply air to 70°F.

In 1999, a ventilation design company conductedan overhaul of the HVAC system at the SRC tobring the system back to design specifications forthe building. The inside of the AHUs, includingthe evaporation coils, were pressure washed. Theold condensate pans were removed and replacedwith stainless steel pans fabricated to enhancedrainage and prevent standing water. Accessdoors were installed to allow visual inspection ofthe evaporation coils and interior of the AHU.Interior insulation lining supply ductwork wasremoved where possible and replaced withexterior insulation. The interior insulation left inplace was cleaned with a vacuum equipped witha High-Efficiency Particulate Air filter (HEPA).After cleaning, a biocide was applied in an effortto inhibit microbial growth. In addition,ultraviolet (UV) lights were installed upstream ofthe cooling coils in an attempt to remove anymicrobial contaminants that may be present in theairstream and to promote cleaning of theevaporation coils. Remediation of the AHUs alsoincluded replacing worn mechanical equipment.

Inducer fans were installed at the OA intakes toactively bring OA into the building. Filtrationefficiency was greatly improved when the filtersection of the AHUs was replaced with filterhousings capable of handling higher-efficiencyfilters. All pneumatic controls were replaced withelectronic controls. The building was pressurizedto maintain a positive pressure relative to theoutdoors. Furthermore, a test and balance of theHVAC system was performed in the spring of2000 (after modifications) to bring the


performance of the equipment back to the originaloperating specifications. This was to ensure thatair would be properly distributed according tooriginal design specifications of the system, whichwere determined when the building was built.

Prior Building Surveys Indoor air quality (IAQ) surveys were previouslyperformed by private consulting firms at therequest of Southwest Airlines. NIOSH receivedcopies of consultant reports performed on thefollowing dates: October 6, 1995; August 16,1996 (with a follow-up survey by the samecompany on October 22, 1996); May 8, 1997;February 22, 1998; and November 2, 18, and 19,1998. All of these surveys focused on IAQ issuesin the reservations center, with the exception ofthe survey conducted on May 8, 1997, whichconcentrated on asbestos. Due to the number ofsurveys performed in the last five years, only themost recent survey performed prior to the NIOSHsite visit will be discussed.

On November 2, 1998, a private consultantconducted an initial site visit at the SRC, duringwhich a visual inspection of the building tookplace and limited environmental samples werecollected. Based on the initial site visit, asampling protocol was designed for a morecomprehensive IAQ survey at the building. Thesampling protocol included the following: airmonitoring for volatile organic compounds(VOCs), microbial VOCs, fungi, mold spores,formaldehyde and other aldehydes, and endotoxin;bulk dust and material samples for determinationof potential fungal or endotoxin sources; directreading measurements of CO2, carbon monoxide(CO), temperature, relative humidity (RH),airborne particles; and an inspection of the HVACsystem components. Air sampling revealed noamplification of airborne fungal levels in theindoor environment when compared to levels inoutdoor air. It was also reported that air samplingrevealed levels of VOCs, microbial VOCs, moldspores, formaldehyde and other aldehydes, andendotoxin to be within acceptable limits for

indoor environments. Bulk dust and materialsamples had non-detectable to low levels ofcockroach and dust mite allergens, and endotoxinlevels were typical of those expected in buildingdust. Cat allergens measured in the samplesrevealed levels close to the action level of concernfor people allergic to cat dander. Settled buildingdust revealed the presence of fungi, such asCladosporium, Aspergillus, Penicillium, andEurotium. In addition, bulk dust and materialsamples from the HVAC system, includinginternal insulation, revealed Cladosporium,Aspergillus, and Pencillium. Direct readingmeasurements for CO2, CO, temperature, RH, andairborne particles were within acceptable limits orrecommended ranges, with the exception of somelocations that exceeded 60% RH. Inspection ofthe HVAC system components revealed a minimalamount of OA being brought into the building,inefficient filtration, drain pans with standingwater, and mechanical rooms being used asstorage rooms (this was before the ventilationoverhaul that began in 1999). The consultantsrecommended improved housekeepingprocedures; identifying sources of water intrusion,repairing water leaks, and replacing water-damaged materials; determining if the HVACsystem should be redesigned; further testing toverify the extent of fungal colonization on HVACairstream surfaces, maintaining sanitaryconditions in the mechanical equipment roomswhere the AHUs are located; ensuring the drainpans allow for complete drainage; increasing filterefficiency; and modifying the system so thatoutdoor air could be properly dehumidified. Theyalso recommended that designated smoking areasbe separately ventilated and negativelypressurized. They also stated that any visiblemold growth, such as that found in the “coldroom” (a former computer room), should beremoved according to mold remediation protocols.

After the consultant’s survey, however, OSHAcontinued to receive health complaints fromemployees working at the SRC. A request forNIOSH to conduct a health hazard evaluation(HHE) was generated by management in April


2000. When NIOSH learned that OSHA wascurrently conducting an investigation at thebuilding, OSHA was contacted and it was decidedthat OSHA would also submit a request forNIOSH’s assistance so that all concerns would beaddressed.

METHODS

Industrial HygieneA walk-through inspection of the building interiorand exterior was conducted immediatelyfollowing the opening conference. NIOSHinvestigators inspected the interior and exterior ofthe building for evidence of water damage andfungal contamination to identify potential sourcesof microbial contamination and pathways formoisture vapor intrusion into the building. Thesix large Trane® HVAC units, located inmechanical rooms both inside and outside out ofthe building, and the roof were also inspected.

Two bulk material samples were collected fromthe interior insulation in a supply air duct abovequadrant A to determine if microbial growthexisted on an airstream surface. The bulk samplesconsisted of an approximate two-square-inchsection cut from the insulation. Additionally, sixbulk dust samples were collected by micro-vacuuming three-square-foot sections of carpet onthe walls and floor in quadrant B, C, and D, thefloor of the hallway between quadrant C and D,and the floor in a private office. The sampleswere split and the dust components of the sixsurface vacuum samples were thenmicroscopically characterized. Dilutions werealso made of the contents from the surfacevacuum samples. These dilutions were thenplaced onto two different nutrient media, maltextract agar (MEA) and cornmeal agar (CMA), todetermine fungal genera concentration.

Five sticky tape surface samples were collectedfrom visibly contaminated areas under sinks in thewomen’s restroom near the break room. Clearadhesive tape was lightly pressed against the area

of suspected growth. The tape sample was thenremoved and mounted (in the field) to a glass slidefor subsequent optical analysis. The tapecontained a portion of the fungal sample intact onthe adhesive surface. All bulk material and tapesamples were placed in clean polyethylene bagsand sent to an environmental microbiologicallaboratory to quantitatively and qualitativelydetermine bacterial and fungal species andevaluate the presence of fungal spores/hyphae.

Indicators of occupant comfort were measured invarious locations throughout the reservationscenter and outdoors. Real-time CO2, temperature,and RH measurements were taken using a TSI Q-Track®, Model 8550, hand-held, battery-operatedIAQ monitor. This portable monitor uses a non-dispersive infrared absorption (NDIR) sensor tomeasure CO2 in the range of 0-5000 ppm, with anaccuracy of ±3% of reading ±50 ppm at 25°C. Itis capable of measuring temperature in the rangeof 32 to 122°F, with an accuracy of 1°F. Thisinstrument also measures RH in the range of 5 to95%, with an accuracy of ±3%. Temperature andRH measurements were also collected and loggedfor a continuous 24-hour period using the Q-Trackand HOBO H8 Pro Series loggers. These battery-operated loggers use an internal temperaturesensor and external RH sensor. The operatingrange is -22 to 122°F and 0 to 100% RH.Moisture incursion measurements were collectedusing a Delmhorst Instrument Company MoistureTester, Model BD-9, battery-operated detector.This meter provides direct readings for moisturecontent in the range of 8 to 50% on wood. Areference scale is used for comparative readingson non-wood materials. This portable instrumentuses the amount of electrical conductivity in thematerial being tested to determine its moisturecontent. Moisture readings were also collectedusing a battery-operated Tramex MoistureEncounter for non-destructive moisture detection.

An Instrument Technology, Inc., Modelno.125010, rigid boroscope was used to lookinside the wall between quadrant A and B toinspect interior drywall for any signs of visible


contamination. The boroscope was equipped witha 150W light source.

Qualitative airflow measurements were performedusing ventilation smoke tubes to determineairflow patterns throughout the building. Thesemeasurements determined whether areas weremaintained under positive, negative, or neutralpressures. Airflow measurements were made atall building entrances, restroom entrances, andenclosed offices and rooms within the building.

MedicalConfidential interviews were conducted withworkers to assess the types of health concernsthey have been experiencing. Workers were askedto describe health concerns and symptoms thatthey experienced, when these symptoms firstoccurred, and how long these symptoms hadpersisted. Workers who participated in theconfidential interviews were selected by unionrepresentatives as workers who believed they hadbeen most affected by work-related exposures. Inaddition, union representatives announced thatinterviews were available to any worker whowished to participate.

EVALUATION CRITERIANIOSH investigators have completed over 1,200investigations of the occupational indoorenvironment in a wide variety of non-industrialsettings. Almost all of these investigations havebeen conducted since 1979. Overall, thesymptoms and health complaints reported bybuilding occupants have been diverse and usuallynot suggestive of any particular medical diagnosisor readily associated with a causative agent.Symptoms frequently reported include headaches,unusual fatigue, itching or burning eyes, skinirritation, nasal congestion, dry or irritated throats,and other respiratory irritations. Typically, theworkplace environment has been implicatedbecause workers often report that their symptomslessen or resolve when they leave the building.

A number of published studies have reported ahigh prevalence of symptoms among occupants ofoffice buildings.1,2,3,4,5 Scientists investigatingindoor environmental problems believe that thereare multiple factors contributing to building-related occupant complaints.6,7 Among thesefactors are imprecisely-defined characteristics ofHVAC systems, cumulative effects of exposure tolow concentrations of multiple chemicalpollutants, odors, elevated concentrations ofparticulate matter, microbiological contamination,and physical factors such as thermal comfort,lighting, and noise.8,9,10,11,12,13 Design,maintenance, and operation of HVAC systems arecritical to their proper functioning and provisionof healthy and thermally comfortable indoorenvironments. Indoor environmental pollutantscan arise from either outdoor sources or indoorsources.

Other studies have shown that occupantperceptions of the indoor environment are moreclosely related to the occurrence of symptomsthan any measured indoor contaminant orcondition.14,15,16 Some studies have shownrelationships between psychological, social, andorganizational factors in the workplace and theoccurrence of symptoms and comfortcomplaints.16,17,18,19

Less often, an illness may be found to bespecifically related to something in the buildingenvironment. Some examples of potentiallybuilding-related illnesses are allergic rhinitis,allergic asthma, hypersensitivity pneumonitis,Legionnaires’ disease, Pontiac fever, and carbonmonoxide poisoning. The first three conditionscan be caused by various microorganisms or otherorganic material. Legionnaires’ disease andPontiac fever are caused by Legionella bacteria.Sources of carbon monoxide include vehicleexhaust and inadequately ventilated keroseneheaters or other fuel-burning appliances.

Environmental problems NIOSH investigatorshave found in the non-industrial indoorenvironment have included the following: poor air


quality due to ventilation system deficiencies,overcrowding, volatile organic chemicals fromoffice furnishings, emissions from officemachines and from structural components of thebuilding and its contents, tobacco smoke,microbiological contamination, and outside airpollutants; comfort problems due to impropertemperature and RH conditions, poor lighting, andunacceptable noise levels; adverse ergonomicconditions; and job-related psychosocial stressors.In most cases, however, these indoorenvironmental problems could not be directlylinked to the health effects reported by thebuilding’s occupants.

Standards specific for the non-industrial indoorenvironment do not exist. NIOSH, theOccupational Safety and Health Administration(OSHA), and the American Conference ofGovernmental Industrial Hygienists (ACGIH),have published regulatory standards orrecommended limits for occupational exposures tospecific chemical and physical agents.20,21,22 Withfew exceptions, pollutant concentrations observedin non-industrial indoor environments fall wellbelow these published occupational standards orrecommended exposure limits. The AmericanSociety of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) has publishedrecommended building ventilation design criteriaand thermal comfort guidelines.23, 24 The ACGIHhas also developed a manual of guidelines forapproaching investigations of building-relatedcomplaints that might be caused by airborne livingorganisms or their effluents.25

Measurements of indoor environmentalcontaminants have generally not proved to behelpful in determining the cause of symptoms andcomplaints, except where there are strong orunusual sources, or a proven relationship betweencontaminants and specific building-relatedillnesses. The low-level concentrations ofparticles and variable mixtures of organicmaterials usually found are difficult to interpretand usually impossible to causally link toobserved and reported health symptoms.However, measuring ventilation and comfort

indicators such as CO2, temperature, and RH, hasproven useful in the early stages of aninvestigation in providing information relative tothe proper functioning and control of HVACsystems.

NIOSH and the Environmental Protection Agency(EPA) jointly published a manual on building airquality, written to help prevent environmentalproblems in buildings and solve problems whenthey occur.26 This manual suggests that indoorenvironmental quality (IEQ) is a constantlychanging interaction of a complex set of factors.Four of the most important elements involved inthe development of IEQ problems are: (1) a sourceof odors or contaminants; (2) a problem with thedesign or operation of the HVAC system; (3) apathway between the contaminant source and thelocation of the complaint; and (4) the buildingoccupants. A basic understanding of these factorsis critical to preventing, investigating, andresolving IEQ problems. Information aboutexposures and health effects relevant to thisinvestigation is given below.

MicroorganismsMicroorganisms (including fungi and bacteria) arenormal inhabitants of the environment. Thesaprophytic varieties (those utilizing non-livingorganic matter as a food source) inhabit soil,vegetation, water, or any reservoir that canprovide an adequate supply of a nutrient substrate.Under the appropriate conditions (optimumtemperature, pH, and with sufficient moisture andavailable nutrients) saprophytic microorganismpopulations can be amplified. Through variousmechanisms, these organisms can then bedisseminated as individual cells, or in associationwith soil or dust particles or water droplets. In theoutdoor environment, the levels of microbialaerosols will vary according to the geographiclocation, climatic conditions, and surroundingactivity. In a “normal” indoor environment,where there is no unusual source ofmicroorganisms, the level of microorganisms mayvary somewhat as a function of the cleanliness of


the HVAC system and the numbers and activitylevel of the occupants. Generally, the indoorlevels are expected to be below the outdoor levels(depending on HVAC system filter efficiency),with consistently similar ranking among themicrobial species.27,28

The current strategy for on-site evaluation ofenvironmental microbial contamination involvesa comprehensive inspection to identify sources(reservoirs) of microbial growth and potentialroutes of dissemination. In those locations wherecontamination is visibly evident or suspected, bulksamples may be collected to identify thepredominant species (fungi, bacteria, andthermoactinomycetes). In limited situations, airsamples may be collected to document thepresence of a suspected microbial contaminant.Airborne dissemination (characterized by elevatedindoor levels relative to outdoor levels, and ananomalous ranking among the microbial species)associated with occupant health effects suggeststhat the contaminant may be responsible for thehealth effects.

Penicillium

The blue-green molds of Penicillium are commoncontaminants of indoor environments. Exposureto Penicillium can occur as a result ofcontaminated humidifier water and moldy HVACsystems. Inhalation of airborne spores is themajor route of human exposure. These molds arecommon contaminants of agriculturalcommodities, and some of the mycotoxinsproduced by these species are also produced byfungi common in house dust.29 Penicilliuminfections of clinical importance are very rare,although this mold has been associated withasthma and hypersensitivity pneumonitis.30

Presently, Penicillium mycotoxins are not knownto be a serious health threat in water-damagedbuildings.31

Carbon DioxideCO2 is a normal constituent of exhaled breath, andif monitored at equilibrium concentrations in abuilding, may be useful as a screening techniqueto evaluate whether adequate quantities of freshair are being introduced into an occupied space.The American National Standards Institute(ANSI)/ASHRAE Standard 62-1989, Ventilationfor Acceptable Indoor Air Quality, recommendsoutdoor air supply rates of 20 cubic feet perminute per person (cfm/person) for office spacesand conference rooms, 15 cfm/person forreception areas, classrooms, libraries,auditoriums, and corridors, and 60 cfm/person forsmoking lounges. Maintaining the recommendedASHRAE OA supply rates when the OA is ofgood quality, and there are no significant indooremission sources, should provide for acceptableIAQ.

CO2 is not considered a building air pollutant, butCO2 concentration is used as an indicator of theadequacy of outside air supplied to occupiedareas. Indoor CO2 concentrations are normallyhigher than the generally constant ambient CO2concentration (range 300-350 ppm). ASHRAEStandard 62-1989 recommends 1000 ppm as theupper limit for comfort (odor) reasons.23, 31 Whenindoor CO2 concentrations exceed 800 ppm inareas where the only known source is exhaledbreath, inadequate ventilation is suspected.32

Elevated CO2 concentrations suggest that otherindoor contaminants may also be increased. It isimportant to note that CO2 is not an effectiveindicator of ventilation adequacy if the ventilatedarea is not occupied at its usual level when themeasurements are made.


Temperature and RelativeHumidityTemperature and RH measurements are oftencollected as part of an indoor environmentalquality investigation because these parametersaffect the perception of comfort in an indoorenvironment. The perception of thermal comfortis related to one’s metabolic heat production, thetransfer of heat to the environment, physiologicaladjustments, and body temperatures.33 Heattransfer from the body to the environment isinfluenced by factors such as temperature,humidity, air movement, personal activities, andclothing. The ASHRAE Standard 55-1992,specifies conditions in which 80% or more of theoccupants would be expected to find theenvironment thermally comfortable.24 Assuminglow air movement, 60% RH and sedentary jobtasks, the temperatures recommended byASHRAE range from 68-74°F in the winter, andfrom 73-79°F in the summer. ASHRAE alsorecommends that RH be maintained between 30and 60%.23 Excessive humidity can support thegrowth of microorganisms, while low RH couldpossibly cause the eyes and upper respiratory tractto dry which may result in irritation.

RESULTS

Industrial Hygiene

Visual Inspection

Visible fungal growth was not observed onbuilding materials during the walk-throughinspection of the interior of the building, with theexception of in the women’s and men’s restroomsnear the break room. Evidence of water damagewas not observed in the building, with theexception of a few ceiling tiles located in the coldroom. Building maintenance was in the process ofreplacing damaged tiles at the time of the NIOSHsite visit. Small areas of carpet on the walls ofquadrant A and B were peeled back to check the

underlying drywall for visible signs of waterincursion or microbial growth. No evidence ofpast water incursion or visible microbialcolonization were observed in these areas.However, lack of maintenance and housekeepingon the carpeted walls in all four quadrants wasapparent. An accumulation of dust and dirt wasobserved on these surfaces.

Areas where moisture incursion would likelyoccur (along exterior walls, carpeted floors, andaround windows and entrances) were probed witha moisture meter to qualitatively assess residualamounts of water suggesting past water incursionproblems. No moisture problems were detected inthese areas. One area around the large rectangularwindows in the reception area showed evidence ofwater damage, however no moisture was detectedin the wood surrounding the windows. Areas inthe break room, where water damage or leaks hadbeen reported to occur (beneath the sinks, insidethe cabinets, and along the interior and exteriordrywall), were also checked for moisture content.These areas showed a minimal, if any, amount ofmoisture content. The plywood beneath the sinksin the women’s restroom (closest to the breakroom) revealed some moisture content in the sameareas of the visible mold (this was reportedly dueto water leaking between the sink and the sinkcutout). Areas where wallpaper was peeling at theseams were also checked for moisture. Nomoisture was detected. The carpeted walls andfloors were also checked. The quadrant wallsconsisted of two layers of drywall covered bycarpet. The original layer of drywall on a wall inquadrant A (the wall that separates quadrant Afrom quadrant B) showed a minimal amount ofmoisture in a small area.

Inspection of the interior drywall of the wallseparating quadrant A and B using the rigidboroscope did not reveal any evidence of visiblemicrobial colonization. The interior of the wallswas inspected from above the ceiling, as well as ata few locations along the floor spanning the lengthof the partition wall. This particular wall wasinvestigated at the request of employees and unionrepresentatives due to health complaints


originating from employees who sat in these twoquadrants. The ventilation blueprints and balance test resultswere reviewed, the OA intakes were visuallyexamined, and the condition of the air filters,coils, drain pans, and other interior components offour randomly selected Air Handling Units(AHUs) were checked. The test and balancereport showed that the system had been properlybalanced back to original performancespecifications earlier in the year. OA is nowactively pulled in using both induction fans andthe fans in the AHUs. Protective covers havebeen placed over the intakes to prevent water ordebris from collecting around the intake. This hadbeen prompted by construction of apartmentbuildings that was taking place behind quadrant Aand D at the time of our site visit.

Inspection of the interior components of theHVAC units servicing the reservations center didnot reveal any evidence of microbialcontamination. The interior of the AHUsappeared dry. No mineral deposits were observedon the interior insulation of the AHUs, whichwould indicate recent water damage. Thecondensation drip pans appeared in goodcondition with proper drainage. There were noobservable water marks that would indicate aproblem with standing water. The pre- andsecondary filters fit properly, minimizing theamount of air that can flow around the filters andenter the AHU without proper filtration. Thesewer vents on the roof of the building wereinspected, and all were clear of debris with theexception of one which was clogged with leaves.Building maintenance was aware of the problemand intended to clear the vent. NIOSH was alsoinformed by building management that new sewervent covers had been ordered to replace the oldones that had deteriorated.

Bulk Sample Analysis

Tape samples taken from plywood beneath thesinks in the women’s restroom near the breakroom revealed mostly wood fibers and paint andskin flakes, with no obvious sign of fungalgrowth. However, two of the five sticky tapesamples suggested fungal growth. One tapesample revealed a few yeast cells, and the otherrevealed a few fungal hyphae and a few loosefungal spores of unidentified fungi. Fungalconcentrations from analysis of two bulk materialsamples of interior insulation taken within asupply duct above quadrant A ranged from non-detectable (ND) to 7.1x104 colony forming unitsper gram of material (CFU/g). The bulkinsulation sample taken within the supply air ductclose to the wall separating quadrant A and B hadND (< 758 CFU/g) fungal concentrations whencultured in 2% MEA and ND bacterialconcentrations (< 758 CFU/g) when cultured intryptic soy agar (TSA). The bulk insulationsample taken from within the same supply air ductat an area above the center aisle in quadrant Arevealed a fungal concentration of 7.1x104 CFU/gwhen cultured in an MEA medium.Cladosporium cladosporioides was the onlyspecies detected. When TSA media was used toculture the same sample, a ND (< 893 CFU/g)bacterial concentration occurred.

Dust component results from the six bulk dustsamples that were microscopically characterizedare presented in Table 1. Mineral crystals, skinflakes, and cellulose fibers were the predominantcomponents in all six surface vacuum samples,ranging from 5% to 70% of total matter detected.Trace elements of fungal matter were detected inall six samples.

The fungal genera and concentrations resultingfrom the bulk dust sample culture analysis arepresented in Table 2. Results are shownseparately for the two nutrient media used duringanalysis, CMA and MEA. Fungal concentrationsranged from 1.4x103 CFU/g to 1.5x105 CFU/g onthe CMA nutrient media, and from 1.5x103 CFU/g


to 1.2x105 CFU/g on the MEA nutrient media.The predominant fungal genera identified on bothnutrient media were Penicillium, Acremonium,and Cladosporium. The bulk dust sample takenfrom the carpeted wall in quadrant B in an areaclose to the front of quadrant revealed aPenicillium concentration of 1.3x105 CFU/g whencultured on CMA and 1.1x105 CFU/g whencultured on MEA. Comfort Parameters

Measurements taken in the morning (using the Q-track) indicated an overall mean temperature inthe reservations center of 74°F. Temperaturesranged from 71° to 76°F. The overall mean RH inthe reservations center was 50%, and ranged from44% to 53%. OA temperature was 79°F, andoutdoor RH was 80%, when measured at 10:00a.m. The overall mean CO2 level in the buildingwas 573 ppm, with a range of 530 to 650 ppm, incomparison with the measured outdoor CO2 levelof 350 ppm. Temperature measurements taken inthe smoking room, break room, and training roomwere 1° to 2°F cooler than the rangerecommended by ASHRAE (for comfort purposesin the summer months) in Standard 55-1992.

Afternoon temperature measurements (taken withthe Q-track) indicated an overall meantemperature of 73°F in the building.Temperatures ranged from 72° to 74°F. Theoverall mean RH in the reservations center was50%, ranging from 43% to 53%. The overallmean CO2 level in the building was 598 ppm, witha range of 550 to 680 ppm. Temperaturemeasurements taken in the smoking room, breakroom, and training room were 1°F cooler than thecomfort range recommended by ASHRAE inStandard 55-1992. None of the RH measurementsexceeded the range recommended by ASHRAE inStandard 55-1992, and none of the CO2measurements exceeded the NIOSHrecommendation of 800 ppm. The overall meantemperature, RH, and CO2 remained relativelyconsistent throughout the day.

Figures 2-11 graphically illustrate the temperaturevariations at 5-minute intervals over a 24-hourperiod at different locations in the reservationscenter and outdoors. The locations are as follows:(1) quadrant A; (2) quadrant B; (3) quadrant C;(4) quadrant D; (5) console area; (6) frontreception area; (7) break room; (8) first aid room;(9) Q & A office; (10) union shop steward’soffice; and (11) outdoors. The temperaturevaried from less than 1°- 3°F in the fourquadrants. Quadrant B had the coolesttemperature (72.5°F), measured fromapproximately 8:30 p.m. to 8:30 a.m. Thiscorresponds to the times that the quadrant isunoccupied (8:30 p.m. to 8:00 a.m.). Figure 8shows the most variation in temperature(approximately 73° to 77°F) in comparison withthe other locations. This data logger was placedin the break room on top of a drink machine bythe television. Although the temperature rangeonly spanned approximately 4°F, the temperaturespeaked at the upper and lower extremes in acontinuous pattern from approximately 8:45 a.m.on June 29, 2000, through 8:51 a.m. on June 30,2000. The offices around the perimeter of thequadrants exhibited more variable temperaturepatterns than those measured within the quadrants.The first aid and Q&A office (see figure 9 and 10)showed warmer temperature trends whencompared with the remaining locations (up to80°F), however the temperatures dropped andwere within ASHRAE’s recommended comfortrange between 8:00 a.m. and 4:00 p.m.Temperatures logged in the shop steward’s office(see figure 11) also showed more variation thanwithin the quadrants, but the temperature rangewas approximately 4°F cooler than the otheroffices. All of the offices are serviced by oneAHU. The instrument placed outdoors wasdirectly in the sun in the afternoon, most likelycausing the very high temperature readings (seefigure 12).

MedicalThirteen workers were interviewed during thetwo-day site visit. Four of 13 workers reported


itchy watery eyes and a runny nose, 4 workersreported chronic sinus infections, 4 reportedheadaches (in some cases self-described asmigraine), 3 reported sore throat, 3 reportedfatigue, and 2 persons reported shortness ofbreath. Five persons noted that their symptomswere aggravated when sitting in quadrant A. Inaddition, at least 2 employees described chronicdebilitating conditions of unknown etiology thatare being managed by their personal physician.

DISCUSSION ANDCONCLUSIONS

Microbial growth and proliferation requires anutrient source, adequate moisture, and anappropriate temperature. All of these factors mustbe present to achieve optimum conditions formicroorganisms to grow. However, limitedevidence of water accumulation or moistureincursion was observed during the site visit (a fewdamaged ceiling tiles, beneath the sinks in awomen’s restroom, and by windows in the frontentrance/reception area). Visual inspection ofbuilding materials in the reservations center didnot reveal the existence of microbial reservoirs.In addition, moisture incursion measurements didnot reveal moist conditions which would beneeded to sustain growth of microorganisms.

The visible mold observed beneath the sinks in thewomen’s restroom near the break room wasconfirmed in two of the five tape samplescollected. Although the fungi could not beidentified, the yeast cells and fungal hyphae andspores detected suggested fungal growth waspresent. This is most likely due to water leaksbetween the sink and sink cutout due todeteriorating caulking.

No accumulation of dust or dirt, or any evidenceof microbial growth was observed, in the interiorinsulation in a supply duct above quadrant A.However, one of the two bulk material samples ofinterior insulation taken from within the supply

duct identified Cladosporium cladosporioides.Water spray from air movement over the coolingcoils results in a marginal amount of waterdeposition in supply ducts downstream of thecooling coils. Thus, it is not unexpected to seesmall counts of this type of fungi. But the lowconcentration detected in the sample, and the lackof grossly apparent contamination do not suggestthe need to replace the insulation in the supplyducts.

The predominant fungal genera identified throughculturable analysis of the bulk dust samplesincluded the allergens Penicillium, Acremonium,and Cladosporium. Although found in varyingconcentrations, one of these species was either thepredominant or second most predominant speciesin all six of the bulk dust samples. However, noother evidence was found that would suggest thatan amplifying source of microbial growth existedbeneath the carpeted walls or floors in the any ofthe four quadrants. Although carpeting providesan organic nutrient source, a continuous source ofmoisture must be present for microbial growth tothrive. No evidence of moisture incursion wasfound through visual inspection and testing withthe invasive and non-invasive moisture meters. Adefinitive explanation addressing the origin of thePenicillium can not be given because there aremany possible explanations. For example, it ispossible that the colonies of Penicillium detectedwere residual growth from a previous moistureincursion event. It is also possible that the fungicould have been carried through the air, possiblyoriginating from the ventilation system before itwas remediated, and deposited on the carpet.However, regardless of the origin, it is difficult toconclude that a marginal reservoir identified inone out of six samples is indicative of a microbialgrowth problem.

Qualitative smoke tube tests indicated that thebuilding was maintained under a positive pressurewith respect to the outdoor environment. Thiswill ensure that unconditioned and unfiltered airdoes not leak into the building through cracks andother entry points. Positive pressure in the


building will also maintain zone control anddecrease temperature fluctuations. Smoke tubetests also indicated that the smoking break roomwas under negative pressure. This should keepcigarette smoke from entering other areas of thereservation center. However, cross-draftsintroduced through opening doors could disruptthe airflow and allow some smoke to escape thearea if the negative pressure is not strong enoughto overcome the cross-drafts. Thus, it is importantthat this room be maintained under strongnegative pressure relative to its surroundings at alltimes to prevent migration of cigarette smoke intonon-smoking areas.

Measured temperatures in quadrant B, the frontreception area, the Q&A office, and the shopsteward’s office were from 2°F below to 1°Fabove ASHRAE’s recommended range for thesummer months (73-79°F). However, with theexception of the shop steward’s office, theseslight variations outside the recommended rangeoccurred during either unoccupied, or lowoccupancy times of the day. Temperatures in theremaining locations measured were within therange recommended by ASHRAE Standard 55-1992. Temperature patterns in the reservationscenter were fairly consistent, with the exceptionof the temperature fluctuations illustrated in thebreak room. This is most likely due to thefrequency of outside air being introduced into thebreak room when employees enter or exit theoutdoor break area, which is accessible through adoor in the break room. Certain areas of thereservations center remain occupied for 24 hoursand, as a result, temperature patterns should beuniform and remain stable at all times. RHmeasured in the building indicated that maximumlevels were approaching the upper limitrecommended by ASHRAE Standard 55-1992.This factor suggests that the current ventilationsystem is not sufficiently conditioning the intakeair before it is delivered to the building.

CO2 measurements below the NIOSH guideline of800 ppm indicate that the HVAC system isproviding adequate amounts of outdoor air to theoccupied areas. This indicates that the remediated

HVAC system is capable of maintaining outdoorair supply rates of at least 20 cfm/person for officespaces, the amount recommended by ASHRAEStandard 62-1989.23 The current AHUs utilizedirect electronically controlled variable andconstant air volume boxes to control temperatureand the amount of OA brought into the building.

The health effects described by the interviewedemployees were, on the whole, not suggestive ofa shared exposure in the SRC. The symptomsdescribed by some of the workers were consistentwith exposures to allergens. These symptomsincluded itchy watery eyes, headache, and fatigue.Although these symptoms were reported at work,they were not exclusive to the work environment(some of the workers indicated that thesesymptoms occurred both at work and away fromwork). The environmental evaluation of thebuilding did not identify an obvious source ofmold in the building. Furthermore, this buildingis located in a climate where seasonal allergies arecommon. With no obvious source of allergensunique to the work environment, it is most likelythat the allergic symptoms described by workersare the result of exposure to antigens in theexternal environment. However, buildingconditions can be a problem for those who have ahistory of allergies, especially during periodswhen the building is being repaired or renovatedand steps should be taken to keep work areasclean and minimize dust migration duringrenovation work.

In conclusion, the limited evidence of visualmicrobial colonization (one area); lack of waterincursion evidence; and proper operatingcondition of the HVAC system in the SouthwestAirlines SRC indicates that a microbial growthproblem did not exist in this building at the timeof the NIOSH site visit.

RECOMMENDATIONS1. The carpeting on the walls of the quadrantsshould be replaced with a non-carpeted, acousticalmaterial that will be easier to keep clean and to


dry in instances of water incursion. Highlyporous materials, such as carpet, can act as a sinkfor materials found in the air that may depositthere, creating an organic nutrient source.However, if an acceptable alternate to thecarpeting can not be found, then special care mustbe given to the new carpet to reduce thepossibility of microbial growth. The carpeting onthe walls should be HEPA vacuumed (used toprevent re-entrainment of debris into the air) on aweekly basis, at a minimum, to prevent buildup ofdust and debris, which can act as a nutrient sourcefor microbial growth. In addition, any episodes ofwater incursion should be dealt with immediatelyand water should immediately be removed fromthe carpet. Heat fans should be used within 24-48hours to dry the carpets. If they can not be driedwithin 24-48 hours, they should be replaced.Steam or other water-based cleaning methodswhich add moisture to the environment must beused with extreme care and are not recommended.Any soft materials, including carpeted areas, thatbecome wet with sewage-contaminated watershould be promptly discarded. A written programfor dealing with these incidents, proper training ofpersonnel, and the ready availability of thenecessary equipment would help reduce thelikelihood of future problems from events of thisnature (these guidelines are applicable to allporous materials, including furnishings andconstruction materials). In all situations, theunderlying cause of water accumulation must berectified or the possibility of fungal growthoccurring, or reoccurring, will be greatlyincreased.

2. Renovation of the carpeting on the quadrantwalls will result in the disruption of dust, dirt, andany other debris on the carpet. The airbornedissemination of these aerosols is an exposureconcern for the workers completing the task andthe occupants of the building. Additionally, theseaerosols can be spread to other areas of a building,increasing exposure concerns for the remainingoccupants and adding to the difficulty of clean-up.Therefore, it is important that all renovationactivities be conducted with an awareness of the

potential exposures and with minimal disturbanceof the materials.

3. Prior to any renovation, controls should beinstituted that protect both the workers and theadjacent environment. Preferably, the work areashould be unoccupied, and persons havingundergone recent surgery, immune suppressedpeople, or people with chronic inflammatory lungdiseases (e.g., asthma, hypersensitivitypneumonitis, and severe allergies) should bevacated from spaces adjacent to the work area.The work area should be isolated fromsurrounding areas before renovation begins.Covering the area with plastic sheeting andsealing with tape should help contain dust anddebris. The carpet should also be HEPA-vacuumed before removal begins to reducedispersion of any dust, debris, or othercontaminants. The ventilation ducts/grills in thework area and directly adjacent areas should alsobe sealed with plastic sheeting. Once the carpet isremoved from the wall it should be wrapped inplastic before being removed from the building toprevent dissemination of debris into other areas.The work area and areas used by remedialworkers for egress should be HEPA vacuumedafter disposal of the carpet.

4. The moldy plywood beneath the sinks in thewomen’s and men’s restroom near the trainingroom, and in the other restrooms, if needed,should be replaced. The restrooms should bemade inaccessible to employees during theremediation process. Although in this instancecontainment of the work area is not necessary,contaminated materials should be removed fromthe building sealed in plastic to prevent anydissemination into other work areas. Afterremediation the restroom floors should be cleanedwith a damp cloth and/or mop and a detergentsolution. The work areas used by remedialworkers for egress should also be cleaned with aHEPA vacuum if the flooring is carpeted. Allareas should be left dry and visibly free fromcontamination and debris. After the plywood isreplaced, caulking between the sink and sink


cutout should be properly applied to ensure thatwater leakage through this area does not occur.Any faucet leaks, or other plumbing leaks, shouldalso be fixed to prevent water from accumulatingaround the sinks.

5. A few water-damaged ceiling tiles wereobserved in the reservations center, specifically inthe cold room. The facility maintenance specialistwas reportedly in the process of replacing alldamaged ceiling tiles. Although no visible signsof mold were seen on the damaged tiles during theNIOSH inspection, if mold is observed duringremoval, special precautions must be taken duringnon-occupied hours or at times during the leastamount of occupancy. The tiles should becarefully removed from the ceiling grids andindividually bagged inside polyethylene or sturdyplastic to contain any release of mold spores whenthe materials are removed from the building.Applying thin sheets of clear plastic with anadhesive backing to mold-contaminated sectionsof wallboard or ceiling tiles can help to containspores on the side of the wall board that theadhesive plastic is attached.

6. RH in the reservations center must bemaintained at levels below 60% to inhibit moldgrowth.24 Although this was the case at the timeof the NIOSH site visit, measured RH in someareas was approaching 60%. RH levels in theupper end of the acceptable range may be due tothe fact that the cooling coils are over capacity forthe maximum heat load and not capable ofproperly cooling the amount of OA being broughtin. The capacity of the cooling coils should bechecked. For chilled-water systems, temperaturesabove design specifications may result ininsufficient dehumidification and reduced coolingcapacity. HVAC engineers recommend chilledwater temperatures be maintained below 55°F.Chilled water temperatures at the time of theNIOSH site visit were well below 55°F andregularly scheduled maintenance checks shouldensure proper temperature regulation.

7. Sewer drains should be periodically checked toensure that they do not dry up, allowing sewer gas

vapors to escape and subsequently causing anodor problem. This is especially important duringdry periods. Mineral oil can be added toinfrequently used drains if there is a problem withwater evaporating too quickly.

8. According to NIOSH policy, smoking in awork area should not be permitted. To facilitateelimination of tobacco use in the workplace,management and labor should work together todevelop appropriate nonsmoking policies.34

However, until that is achieved, employers candesignate separate, enclosed areas for smokingwith separate ventilation. Smoking areas shouldalso have negative pressure to ensure airflow intothe area rather than back into the airspace of theworkplace.23 The smoking break room was undernegative pressure at the time of the NIOSH sitevisit, however it was reported that prior to theNIOSH site visit this room was under positivepressure. It is important that this room constantlyremain under a strong negative pressure to ensurethat smoke does not migrate to other areas of theworkplace. The outdoor break area is alsodesignated as a smoking area. Although outside,it is a common area to both non-smoking andsmoking employees. Thus, according to NIOSHpolicy this area should be non-smoking. Smokingshould only be permitted in areas designated asstrictly smoking areas.

9. The current service agreements addressing thehousekeeping program and routine operatinginspections, repair services, and annual preventivemaintenance on the building should be diligentlyfollowed and updated as needed. All carpetedareas should be HEPA-vacuumed on a weeklybasis, at a minimum, to prevent buildup of dustand debris, which can act as a nutrient source formicrobial growth. A HEPA vacuum should beused to prevent re-entrainment of aerosols into theair. The supply and return grills should becleaned on a regular basis to prevent dust anddebris accumulation from entering the airstream.Cleaning activities that introduce moisture intothe building, such as steam cleaning carpets,should not be performed in a way that leads toexcessive moisture in porous materials.


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7. Norback D, Michel I, Widstrom J [1990].Indoor air quality and personal factors related tothe sick building syndrome. Scan J Work EnvironHealth. 16:121-128.

8. Morey PR, Shattuck DE [1989]. Role ofventilation in the causation of building-associatedillnesses. Occupational Medicine: State of the ArtReviews. 4(4):625-642.

9. Mendell MJ, Smith AH [1990]. Consistentpattern of elevated symptoms in air-conditionedoffice buildings: A reanalysis of epidemiologicstudies. Am J Public Health. 80(10):1193-1199.

10. Molhave L, Bach B, Pedersen OF [1986].Human reactions during controlled exposures tolow concentrations of organic gases and vapoursknown as normal indoor air pollutants. EnvironInt. 12:167-175.

10. Although the HVAC system appeared in goodcondition at the time of the NIOSH site visit, thecondition of the HVAC system should beroutinely checked and annual preventivemaintenance should be diligently followed toensure proper performance continues. Thisincludes inspection of interior components of theAHUs, such as cooling coils, condensate drippans, and porous internal HVAC duct liners foraccumulation of dust, dirt, or other contaminants,as well as evidence of water damage. Preventivemaintenance should also include inspection ofoutdoor air damper systems and exhaust vents.Any future HVAC upgrades or modificationsrequire that accurate heat load calculations beobtained to ensure proper sizing of equipment. Acomplete test and balance of the system shouldalso be performed to ensure that the systemoperates as intended and that design goals are met.

11. Communication between management andemployees should be increased to facilitate theexchange of concerns about environmentalconditions in the building. Employees should bemade aware of the problems with the building anddecisions that must be made by building managersto address those problems. Forming a safetycommittee consisting of members of management,the union, and employee representatives to act asa liaison between management and the staff isrecommended.

12. Employees who have health concerns such asrhinitis, asthma, and sinusitis should consult theirhealth care provider to determine the cause andproper treatment.

REFERENCES


11. Fanger PO [1989]. The new comfortequation for indoor air quality. ASHRAE J.31(10):33-38.

12. Burge HA [1989]. Indoor air and infectiousdisease. Occupational Medicine: State of the ArtReviews. 4(4):713-722.

13. Robertson AS, McInnes M, Glass D, DaltonG, Burge PS [1989]. Building sickness, aresymptoms related to the office lighting? AnnOccup Hyg. 33(1):47-59.

14. Wallace LA, Nelson CJ, Dunteman G [1991].Workplace characteristics associated with healthand comfort concerns in three office buildings inWashington, D.C. In: Geshwiler M, MontgomeryL, and Moran M, eds. Healthy buildings.Proceedings of the ASHRAE/ICBRSD conferenceIAQ’91. Atlanta, GA. The American Society ofHeating, Refrigeration, and Air-ConditioningEngineers, Inc.

15. Haghighat F, Donnini G, D’Addario R[1992]. Relationship between occupantdiscomfort as perceived and as measuredobjectively. Indoor Environ. 1:112-118.

16. NIOSH [1991]. Hazard evaluation andtechnical assistance report: Library of CongressMadison Building, Washington, D.C. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control, National Institute forOccupational Safety and Health, NIOSH ReportNo. HETA 88-364-2104 - Vol.III.

17. Skov P, Valbjorn O, Pedersen BV [1989].Influence of personal characteristics, job relatedfactors, and psychosocial factors on the sickbuilding syndrome. Scand J Work EnvironHealth. 15:286-295.

18. Boxer PA [1990]. Indoor air quality: Apsychosocial perspective. J Occup Med.32(5):425-428.

19. Baker DB [1989]. Social and organizationalfactors in office building-associated illness.Occupational Medicine: State of the Art Reviews.4(4):607-624.

20. CDC [1992]. NIOSH recommendations foroccupational safety and health: Compendium ofpolicy documents and statements. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control, National Institute forOccupational Safety and Health. DHHS (NIOSH)Publication No. 92-100.

21. Code of Federal Regulations [1989]. OSHATable Z-1-A. 29 CFR 1910.1000. Washington,D.C.: U.S. Government Printing Office, FederalRegister.

22. ACGIH [2000]. 2000 Threshold limit valuesfor chemical substances and physical agents andbiological exposure indices. Cincinnati, OH:American Conference of Governmental IndustrialHygienists.

23. ASHRAE [1999]. Ventilation for acceptableindoor air quality. Atlanta, GA: American Societyfor Heating, Refrigeration, and Air-conditioningEngineers. ANSI/ASHRAE Standard 62-1999.

24. ASHRAE [1992]. Thermal environmentalconditions for human occupancy. Atlanta, GA:American Society of Heating, Refrigeration, andAir-conditioning Engineers. ANSI/ASHRAEStandard 55-1992.

25. ACGIH [1989]. Guidelines for theassessment of bioaerosols in the indoorenvironment. Cincinnati, OH: AmericanConference of Governmental IndustrialHygienists.

26. NIOSH/EPA [1991]. Building air quality: aguide for building owners and facility managers.Cincinnati, OH: U.S. Department of Health andHuman Services, Public Health Service, Centersfor Disease Control, National Institute forOccupational Safety and Health, DHHS (NIOSH)Publication No. 91-114.


27. Burge HA [1988]. Environmental allergy:definition, causes, control. Engineering Solutionsto Indoor Air Problems. Atlanta, GA: AmericanSociety of Heating, Refrigeration, and Air-conditioning Engineers pp. 3-9.

28. Morey MR, Feeley JC [1990]. The landlord,tenant, and investigator: their needs, concerns, andviewpoints. Biological Contaminants in IndoorEnvironments. Baltimore, MD: American Societyfor Testing and Materials pp. 1–20.

29. Sorenson WG [1994]. Aerosolizedmycotoxins: implications for occupationalsettings. Published in Proceedings of theInternational Conference on Fungi and Bacteria inIndoor Air Environments; Health Effects,Detection and Remediation. Johanning E & YangCS, eds. Saratoga Springs, New York, October 6-7, 1994.

30. Malberg P, Rask-Andersen A, Palmgren U,Hoglund S et al [1985]. Exposure tomicroorganisms, febrile and airway-obstructionsymptoms, immune status, and lung function ofSwedish farmers. Scand J Work Health 11:287-93.

31. Jarvis BB [1994]. Mycotoxins in the air:keep your building dry or the bogeyman will getyou. In: Proceedings of the InternationalConference on Fungi and Bacteria in Indoor AirEnvironments. Saratoga Springs, NY, October1994: 35-43.

32. NIOSH [1994]. NIOSH testimony to the U.S.Department of Labor: statement of the NationalInstitute for Occupational Safety and Health.Presented at the public hearing on the proposedrulemaking on Indoor Air Quality, September 28,1994. NIOSH policy statements. Cincinnati, OH:Department of Health and Human Services, PublicHealth Service, Centers for Disease Control andPrevention, National Institute for OccupationalSafety and Health.

33. NIOSH [1986]. Criteria for a recommendedstandard: occupational exposure to hot

environments, revised criteria. Cincinnati, OH:U.S. Department of Health and Human Services,Public Health Service, Centers for DiseaseControl, National Institute for OccupationalSafety and Health, DHHS (NIOSH) PublicationNo. 86-13.

34. NIOSH [1991]. Current Intelligence Bulletin54: environmental tobacco smoke in theworkplace; lung cancer and other health effects.Cincinnati, OH: U.S. Department of Health andHuman Services, Public Health Service, Centersfor Disease Control, National Institute forOccupational Safety and Health, DHHS (NIOSH)Publication No. 91-108.


Table 1Characterization of Bulk Dust Samples

HETA 2000-0268Southwest Airlines San Antonio Reservations Center, San Antonio, TX

June 28-30, 2000

Sample Location Dust Component Percentage (%)

Bulk 1(from the carpeted wall separatingQuad A and B; on Quad B side)

cellulose fibersfiber glassfungal mattermineral crystalsmiscellaneousplant matter/trichomepollenskin flakes starch grains

5tracetrace2031

trace701

Bulk 2(from carpeted wall separating QuadC and main hallway; on Quad C side)

cellulose fibersfiber glassfungal mattermineral crystalsmiscellaneouspollenskin flakes starch grainssynthetic fibers

15tracetrace103

trace7011

Bulk 3(from carpeted rear wall in Quad C)

cellulose fibersfungal mattermineral crystalsmiscellaneousplant matter/trichomepollenskin flakes starch grainssynthetic fibers

40trace

531

trace50

trace1

Bulk 4(from carpeted floor in hallwaybetween Quad C and D)

cellulose fibersfungal mattermineral crystalsmiscellaneouspollenskin flakes starch grainssynthetic fibers

25trace357

trace3021

Table 1Characterization of Bulk Dust Samples


June 28-30, 2000

Sample Location Dust Component Percentage (%)


Bulk 5(from carpeted floor halfway up thecenter aisle in Quad D)

cellulose fibersfungal mattermineral crystalsmiscellaneouspollenskin flakes starch grainssynthetic fibers

5trace504

trace40

trace1

Bulk 6(carpeted floor in union steward’soffice)

cellulose fibersfiber glassfoam particlesfungal mattermineral crystalsmiscellaneousplant matter/trichomepollenrubberskin flakes starch grainssynthetic fibers

25tracetracetrace1561

trace1

5011


Table 2Microbiological Bulk Dust Sample Results


June 28-30, 2000

Sample LocationFungi (MEA†) Fungi (CMA‡)

CFU/g Taxa (%) CFU/g* Taxa (%)

Bulk 1(from the carpeted wall separatingQuad A and B, on Quad B side)

2.0x103 Acremonium (2) 9.8x102 Aspergillus niger (<1) 2.0x103 Aspergillus versicolor(2) 2.0x103 Cladosporium (2) 1.1x105 Penicillium (93) 2.0x103 sterile fungi (2) Total: 1.2x105

1.3x104 Myrothecium (9) 1.3x105 Penicillium (90) 9.8x102 Rhizopus stolonifer (<1) 9.8x102 sterile fungi (<1)

Total: 1.5x105

Bulk 2 (from carpeted wall separating QuadC and main hallway, on Quad Cside)

7.5x103 Aphanocladium (60) 5.0x103 Penicillium (40)

Total: 1.3x104

1.3x104 Aphanocladium (50) 1.3x104 Penicillium (50) Total: 2.5x104

Bulk 3 (from carpeted rear wall in Quad C)

1.3x103 Alternaria alternata (13) 6.6x102 Botrytis (6) 1.3x103 Chaetomium globosum (13) 6.6x102 Nigrospora (6) 1.3x103 Penicillium (13) 4.6x103 Phoma (44) 6.6x102 sterile fungi (6)

Total: 1.0x104

1.3x103 Alternaria alternata (18) 6.6x102 Aureobasiduim pullulans (9) 1.3x103 Chaetomium globosum (18) 6.6x102 Exophiala (9) 6.6x102 Mucor (9) 1.3x103 Phoma (18) 6.6x102 Rhodotorula (9) 6.6x102 sterile fungi (9)

Total: 7.2x103



June 28-30, 2000




Bulk 4 (from carpeted floor in hallwaybetween Quad C and D)

5.9x103 Acremonium (7) 1.2x104 Alternaria alternata (15) 1.5x103 Aspergillus flavus (2) 1.5x103 Aspergillus niger (2) 1.5x103 Aureobasidium pullulans (2) 2.7x104 Cladosporium (33) 3.0x103 Curvularia (4) 4.4x103 Epicoccum nigrum (6) 7.4x103 Penicillium (9) 3.0x103 Rhodotorula glutinis (4) 3.0x103 sterile fungi (4) 1.0x104 yeasts (13)

Total: 8.0x104

4.1x104 Acremonium (37) 5.9x103 Alternaria alternata (5) 1.5x103 Aspergillus sydowii (1) 3.0x103 Aspergillus ustus (3) 1.5x103 Chaetomium globosum (1) 2.5x104 Cladosporium (23) 4.4x103 Curvularia (4) 1.5x103 Drechslera (1) 7.4x103 Penicillium (7) 3.0x103 Phoma (3) 4.4x103 Rhodotorula glutinis (4) 3.0x103 sterile fungi (3) 8.9x103 yeasts (8) Total: 1.1x105



June 28-30, 2000



Page 22 Health Hazard Evaluation Report No. 2000-0268-2812

Bulk 5 (from carpeted floor halfway up thecenter aisle in Quad D)

1.6x102 Acremonium (11) 2.0x102 Alternaria alternata (13) 40 Aureobasidium pullulans (3) 2.8x102 Cladosporium (18) 2.8x102 Curvularia (18) 40 Nigrospora (3) 40 Penicillium (3) 1.6x102 Phoma (11) 80 Rhodotorula glutinis (5) 1.2x102 sterile fungi (8) 1.2x102 yeasts (8)

Total: 1.5x103

1.6x102 Alternaria alternata (11) 80 Aureobasidium pullulans (6) 4.8x102 Cladosporium (34) 2.4x102 Curvularia (17) 40 Myrothecium (3) 80 Penicillium (6) 80 Phoma (6) 40 Rhodotorula glutinis (3) 40 sterile fungi (3) 1.6x102 yeasts (11)

Total: 1.4x103

Bulk 6(carpeted floor in union steward’soffice)

1.6x103 Aspergillus nidulans(5) 2.9x104 Penicillium (95)

Total: 3.1x104

1.6x103 Acremonium (5) 1.6x103 Aspergillus flavus (5) 3.0x104 Penicillium (86) 1.6x103 sterile fungi (5)

Total: 3.4x104

*Concentration is (CFU/sample) if sample amount is non-detectable. †MEA-2% malt extract agar‡CMA-cornmeal agar


Figure 1 Floor Plan of the San Antonio Reservations Center


June 28-30, 2000


Figure 2Temperature Variations in Quadrant A


June 29-30, 2000


Figure 3Temperature Variations in Quadrant B


June 29-30, 2000


Figure 4Temperature Variations in Quadrant C


June 29-30, 2000


Figure 5Temperature Variations in Quadrant D


June 29-30, 2000


Figure 6Temperature Variations in the Console Area


June 29-30, 2000


Figure 7Temperature Variations in the Reception Area


June 29-30, 2000


Figure 8Temperature Variations in the Break Room


June 29-30, 2000


Figure 9Temperature Variations in the First Aid Room


June 29-30, 2000


Figure 10Temperature Variations in the Q & A Office


June 29-30, 2000


Figure 11Temperature Variations in the Shop Steward’s Office


June 29-30, 2000


Figure 12Temperature Variations Outdoors


June 29-30, 2000

For Information on OtherOccupational Safety and Health Concerns

Call NIOSH at:1–800–35–NIOSH (356–4674)or visit the NIOSH Web site at:

www.cdc.gov/niosh

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