Use of passive samplers in the DEARS
We have shown that passive samplers can be successfully used to collect a range of gas phase pollutants during 24-hr integrated sampling in the DEARS. Their ease of use and low participant burden have allowed for collection of a series of criteria pollutant gases, carbonyls and VOCs. As expected, operation of the samplers using only a 24-hr integrated sampling period has resulted in some pollutants being collected at a lower percentage of detectability in some spatial settings. However, use of the PE tubes has shown great promise in the collection of 1,3-butadiene, a hazardous air pollutant of concern, without having to use bulky canister methodologies. Many of the VOCs considered as useful markers of certain emission sources (e.g, mobile sources), appear to be readily detectable by the methodology. Likewise, the use of the PAKS has permitted the measurement of acrolein for both personal and residential settings at concentrations not previously possible using other passive techniques. The DNSH approach is still being refined and it is hoped that improvements in this methodology will result in lower limits of detection and an improved percentage of pollutant detectability as the DEARS progresses. Ogawa samplers represent one of the more time-tested passive approaches. Data from the DEARS indicates that with the exception of SO2, the technique is capable of providing reliable time integrated estimates of criteria pollutant gases in most settings, especially for O3 and NO2 in the Detroit airshed.
