Use of Personal Passive Samplers for Measurement of NO2, NO, and O3 Levels in Panel Studies

not for NO2. For O3, accurate personal exposure measurement remains a challenge and further technical development is required We measured personal exposure to nitrogen dioxide (NO2), nitrogen monoxide (NO), and ozone (O3), using personal passive samplers during three 4-day periods, in a panel study of asthmatics continuing the normal activities of everyday life. Fifty-five adults, mean age 42 years, 53% men, and 39 children, mean age 11 years, 67% boys, wore two Ogawa passive samplers simultaneously: one for O3, the other for NO2 and NO. Mean outdoor pollution was measured at a regional monitoring network. Personal exposure levels were scattered; they were (on average) higher than stationary-site levels for NO and lower for NO2 and O3. In adults, 41% of the variance of personal exposure to NO2 was explained by mean stationary-site measurement levels (P<0.0001). Twenty-one percent additional variance was explained by living near a main road, not having an extractor fan over the cooker, older age, and male sex. NO and O3 personal exposures correlated poorly with stationary-site measurements. In panel studies of the health effects of air pollution, personal exposure to NO2 and NO can be measured satisfactorily by passive samplers: such measurements are necessary for NO but