Comparison between personal and individual exposure to urban air pollutants

This study tested the reliability of a novel method developed for assessing the individual exposure to size-fractionated particulate matter (PM) and gaseous urban pollutants. Individual exposure was defined as the exposure constantly measured in proximity to the subject, even during transfers. Individual exposure was measured using a mobile monitoring unit (MMU), developed to sample simultaneously some urban pollutants of interest for public health purposes. The obtained concentrations were compared with those simultaneously collected in the breathing zone, considered as the gold standard for estimating human exposure to air pollutants. Short-time number concentrations of ultrafine, fine, and coarse particles collected by MMU were characterized by a high predictivity of personal exposures (R2 0.89; slope 0.94-1.17 for PM 10 m), far superior to fixed-site measurements. 5-h time-weighted averages fully explained the variability of ultrafine and fine particles (R2 0.99). The concentrations of gaseous pollutants measured by MMU were less correlated with those collected in the breathing zone (R2 = 0.34-0.65). Nevertheless, the capability of the MMU to detect the variations of personal exposures to O3 and CO was better than that normally observed using fixed measurements, likely due to the placement of the MMU in the different microenvironments where subjects spent their time. Individual exposures measured by the MMU could be of importance in toxicological and epidemiological studies on PM, with the advantage of accounting for exposure to several gaseous co-pollutants.