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• ASHRAE’s recommendations were originally made as Standard 62, “Ventilation for Acceptable Indoor Air Quality.”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 )

More on These Studies

•

So What About Ventilation?

• Ventilation air can solve or improve almost any indoor air problem,

• Cost: equipment and energy• Outdoor air must be better than indoors • Particulates, ozone concerns 

Humidity an Issue

• Moisture from ventilation may change indoor moisture levels and comfort

• Mold grows with moisture, too. • Brand new southern coastal school

added outside air without moisture control. School closed within a year to dry and clean

Bringing The Outside In Our Homes

• Deliver outside air in and push out IA• Exhaust inside air and draw in OA • Balanced methods do both• No single choice

Exhaust –Only Fans

• In most bathrooms, many kitchens• Reasonable price, but…• Where does make-up air come from?

– May draw in radon, mold, garage fumes– May bring in high-humidity air, grow mold– Does this air go to every room?

Exhaust-only House

• Shows fans on, bringing in outside air

Supply-Only

• Air source is known, air delivered into HVAC system to filter, dehumidify, change temperature

• Pushes some air out, no problem. • More expensive, for equipment and for

energy to treat the air• More complicated 

Supply-Only: CARB Study

• Measured chemicals in newer homes• Homes had no OA system, supply-only

system, or balanced systems• None of the 8 supply only systems was

working properly • Chemical levels in these homes

mirrored homes with no ventilation.

Supply-only House

• Shows fans on, bringing in outside air

Balanced ventilation systems

• Exhaust indoor air, deliver outdoor air• Heat exchangers transfer heat, save $

– Heat Recovery Ventilator (HRV) – heat only

– Energy Recovery Ventilator (ERV) – heat and moisture, humid climates

• More $• CA : ERV homes= lower chemicals

ERV/HRV House

• Shows fans on, bringing in outside air

Maintenance

• HVAC requires maintenance.• Recommended 2x/year• Not always done, and not done on

ventilation equipment

Filtration

• Filtration –needed on outside air intakes?

• San Francisco Code 38 requires that outside air delivered to residences near freeways (which have high PM) must use a high grade of filter (MERV 13) to remove some of the PM. 

Other Issues

• If air is mixed well, less ventilation?– Experts on both sides

• Adjustable system? We set temperatures up and down – why not ventilation? Will we set too low?

•

Conclusion

• Air quality is crucial to breath and health• Research suggests greater outside air

ventilation would reduce chronic disease• “Best” system depends on location and

equipment maintenance• U.S. EPA does not recommend

ventilation quantities or delivery methods