For decades, cities across the US have been grappling with the serious problem of unhealthy levels of ozone in outdoor air. Ozone is formed in the atmosphere by photochemical reactions involving nitrogen oxides and volatile organic compounds, which in turn are emitted from motor vehicles, power plants, and a wide variety of other sources. Ozone concentrations peak in the US in the summer months when solar radiation is at its strongest. Numerous epidemiologic studies have found strong associations between short-term exposure to ozone and adverse health effects, including premature mortality.

The goal of this research is to investigate personal exposure to ozone. Our study will
take advantage of a novel personal ozone monitor developed by one of the
co-investigators. Unlike devices used in previous personal exposure studies the new
monitor provides high time resolution and is sensitive enough to measure indoor ozone
concentrations. The research builds a new interdisciplinary collaboration between faculty
in Mechanical Engineering (Milford and Miller), LASP (Avallone) and Environmental Health
at Colorado State University (Peel).

To demonstrate the feasibility and importance of characterizing personal exposures, we will conduct a pilot study of personal exposure concentrations and housing characteristics for adults living in Arvada, CO. Arvada is an older Denver suburb with about 100,000 residents. The Colorado Department of Public Health and Environment (CDPHE) ozone monitor at 9101 W. 57th Ave. in Arvada generally registers among the highest summertime ozone concentrations in the metro area.

Participants homes will be characterized with respect to date of construction, size, floor plan, presence or absence of air conditioning or evaporative cooling, ventilation rates, and proximity to major roadways or other known air pollution sources. The air exchange rates (AER) will be assessed for each sampling room using a tracer gas test protocol with carbon dioxide. Personal ozone concentrations, temperature, relative humidity and approximate location will be monitored for each study subject during the daytime hours for a two-week summertime period, when ambient ozone concentrations are expected to be at their highest. The subjects personal exposure concentrations will be compared with O3 data from the CDPHE monitor in Arvada and with spatially averaged data from across the metro area. To further assist with data interpretation, a daily activity survey will be administered to each subject. Each study participant will be visited once a day to administer the survey, assess the use/status of air conditioning and home ventilation, and to replace batteries in the personal exposure monitors. GPS and temperature and relative humidity data will be used to help interpret the subjects exposure concentration records, by helping determine whether exposures occurred at home or elsewhere, and whether they occurred in or out of doors.