In 2008, the U.S. primary eight-hour National Ambient Air Quality Standard for ozone (EPA,
2008) was changed from 0.08 to 0.075 ppm. While this change appears small, the number of
U.S. counties out of compliance with the standard increased from 85 to 345
(http://www.epa.gov/air/ozonepollution/actions.html). The current ventilation and indoor air
quality standard for commercial buildings by the American Society for Heating, Refrigerating,
and Air Conditioning Engineers (ASHRAE, 2007) requires air cleaning for ozone when the
second highest one hour average ozone concentration exceeds 0.160 ppm, but the standards
committee is considering more stringent ozone air cleaning requirements