Bringing the Outside In: Ventilation for Your Health Henry Slack

Bringing the Outside In: Ventilation for Your Health

Henry SlackU.S. Environmental Protection Agency Region 4

Introduction to Air

• We breathe 20-30 lbs air/day ! • 90% indoors – homes 70%, other bldgs 20% • Indoor air: chemicals, mold, bacteria, dust• Maybe high levels of radon, pesticides,

tobacco smoke, combustion gases • How can we improve out household air?

Ventilation!

• Cleans your air • Lowers levels of every pollutant• Health, productivity gain > energy $• Exploring ventilation, research• Informational, but no firm conclusion• U.S. EPA does not recommend

ventilation quantities or delivery methods

How We Built Homes Long Ago

• Stone, wood, metal materials• Open windows half of year

Outdoor Air = Indoor Air• Lathe and plaster walls (high pH)• Asbestos and lead-based paint• No central heat or A/C - unaffordable!

Homes for the past 50 years

• Carpets, wallboard, Particleboard• Finishes, glues, foam insulation • Computers, printers, copiers (toner)• Cleaning, personal, pesticide chemicals• Central A/C and heat, filters• Yes- shut windows, added chemicals

Attached Garage

• Storing gasoline, paint, pesticide, other chemicals

• Autos (and if on, combustion gases)• Water heaters, even furnaces• No caulk or weather stripping between

garage and kitchen = fumes come in

Ventilation Recommendations

• Florence Nightingale – 1860’s• She + others: around 60 cubic feet of air

per minute per person (CFM/p)• Post-1973 energy crisis, the American

Society of Heating Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommended only 5 CFM/p in non-smoking offices

Ventilation 1980’s - now

• A few years later, ASHRAE raised their recommendation to 15 CFM/p.

• The present recommendation in office buildings is around 13 CFM/p, but the actual figure is calculated on the building size as well as occupancy, so it is not directly comparable.

• The U.S. EPA does not set ventilation standards.

ASHRAE Standard

• ASHRAE’s recommendations were originally made as Standard 62, “Ventilation for Acceptable Indoor Air Quality.” In 2005, this standard was split into 62.1 for most buildings and 62.2 for residential buildings

• Based on best science and “engineering judgment” so new science will change

LEED

• Leadership in Energy and Environmental Design (LEED) buildings could get extra credits for 30% more outside air than ASHRAE 62

Tight Homes

• ASHRAE 62.2 recommends 0.3-0.35 air changes per hour (ACH)

• Some new residences being built tighter without outside air ventilation

• Multi-family as low as 0.03 ACH• Average across two studies: 0.10 ACH

Three Key Ideas

• CO2 may be a pollutant in ways not previously recognized

• Meta-analysis shows health benefits of more OA level off around 50 CFM/person

• More ventilation would pay for itself in offices and schools

Meta-analysis of Ventilation Studies

• Team of leading scientists reviewed 27 papers on health effects and ventilation written through 2005

• Higher ventilation rates in offices, up to about 25 l/s/person [50 CFM] are associated with reduced prevalence of Sick Building Syndrome symptoms

Sundell et al, Indoor Air 2011: 21; 191-204

How Much Outside Air Do We Need?

• 2011 Meta-analysis reviewed 27 separate studies shows health benefits from delivery of more outside air.

• Higher ventilation rates in offices are associated with reduced prevalence of Sick Building Syndrome symptoms (mostly respiratory).

• The effect goes up to about 50 CFM/p (Sundell et al, Indoor Air 2011: 21; 191-204)

50 CFM/person is 3x Current Rates!

• Consistency was found across multiple investigations and different epidemiologic designs for different populations

• Suggests that lowering existing minimum ventilation rates inappropriate, but offered

no support for any specific level of increase

More on the Meta-Analysis

• Consistent across multiple investigations, different countries, different research designs, so strong.

• 50 CFM/p is 3-4x higher than ASHRAE Standard 62 recommends. This study did NOT recommend any particular amount of outside air

• They also didn’t discuss using outside air when local air pollution is bad.

CO2• We all breathe out carbon dioxide (CO2)• CO2 levels may affect our ability to

make decisions. • Typical levels have been viewed as

harmless, although more CO2 makes our blood more acidic.

• Outdoor air has around 400 parts per million (PPM) CO2 right now. A typical office building may see levels go up to 1,000 PPM (or 0.1%) during the day as occupants breathe out. Buildings without ventilation may go much higher, and submarines and space capsules may be 10,000 PPM or more

•

More on CO2

• Outdoor air has around 400 parts per million (PPM) CO2 right now.

• Offices may go up to 1,000 PPM (or 0.1%) during the day

• Buildings without ventilation may go much higher

• Submarines and space capsules may be 10,000 PPM or more

•

Decision Making Tests

• Decision-making tests correlate with leadership skills.

• Reliable: Tested on thousands of people• 22 subjects took tests. Same people,

same room, same day, but the air held different levels of carbon dioxide (CO2) each time: 600 PPM, 1,000 PPM, and 2,500 PPM

CO2 and Decision-making

• 22 subjects completed tests of decision-making performance at 600, 1000, 2500 ppm CO2 , all the same day, but in different order

• Validated decision-making tests (SMS)

Satish, U., et al. Enviro Health Perspect 120: 1671-1677

Result• Result : statistically significant consistent

downward trends on 7 of 9 decision scales

Slides

• Tests were double-blind: neither the subjects nor the technicians giving the tests knew what CO2 levels were present.

• They even changed the order of the CO2 concentrations tested, so that the subject’s level of alertness would not be a factor.

Is Our Children Learning?

• Many school classrooms are over 1,000 ppm; in TX, 21% peak CO2 levels were >3,000 ppm

• Office CO2 levels may be higher in meeting rooms, where decisions are made

Does it Pay?

• Many studies: more ventilation leads to greater productivity in schools, offices

• 1% increase in vent: $3-10,000/year• Doubling ventilation yields productivity

gains of $37 B (energy cost =$0.13 B). Economizers gain $33 B, saving energy but paying $0.28 B for equipment. (Fisk, Building and Environment, 2011 )

Bringing the Outside In: Ventilation for Your Health Henry Slack

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