The relevance of health effects related to ultrafine particles (UFPs; aerodynamic diameter < 100 nm) can be better evaluated using high-resolution strategies for measuring particle number concentrations. In this study, two different portable Condensation Particle Counters (CPCs) were used to measure personal exposure to UFPs in the central area of Milan for one week period during spring, with three sampling sessions per day. Experimental data were continuously collected along an established urban pathway, moving afoot or by different private and public means of transport. Correlation analysis between data measured by two CPCs was performed and general results showed a good agreement, especially at concentrations lower than 2×10 5 particles /cm 3. UFPs measures were divided on the basis of crossed environments or micro-environments, days of the week and day time (hours). The highest measured mean concentrations and data variability were observed during walking time and moving on motorized vehicles (bus and car), indicating that the highest exposure to UFPs can be reached near motorized traffic. The lowest exposures were observed in green areas and in office microenvironments. An appreciable difference between working and non-working days was observed. Concentration patterns and variation by days of the week and time periods appears related to time trends in traffic intensity.
The aim of this work was to quantify the personal exposure of traffic police officers to particulate matter (PM), carbon monoxide (CO), benzene, toluene, ethylbenzene, and xylenes. The contributions of some behavioral, occupational, and meteorological determinants of exposure also were evaluated. Personal exposure to airborne contaminants was measured on 130 selected volunteers in four seasonal sampling sessions. CO was measured with high sampling frequency. A time-activity diary was completed by traffic police officers during their work shift. Mean (median) personal exposure levels of carbon monoxide, respirable particles (PM(resp)), and benzene were 3.51 (3.22) mg/m(3), 128 (115) microg/m(3) and 11.5 (9.6) microg/m(3), respectively. The highest ambient mean levels of PM(resp), CO, and benzene were found during cold seasons. Measurements taken where traffic is directed, schools are guarded, and other outdoor tasks are performed showed the highest median CO concentrations. As expected, wind decreased exposure to CO and benzene. Exposure was not significantly affected by active tobacco smoke. A key finding was that airborne concentrations determined by fixed measurement stations reported in other studies greatly underestimated traffic officers' exposure to airborne contaminants. The proximity to an emission source determined by the occupational activity was the factor that most affected exposure. For this reason, fixed stations are poor predictors of roadside exposures to airborne 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 (R 2 ≥ 0.89; slope 0.94-1.17 for PM < 10 µm), far superior to fixed-site measurements. 5-h time-weighted averages fully explained the variability of ultrafine and fine particles (R 2 > 0.99).The concentrations of gaseous pollutants measured by MMU were less correlated with those collected in the breathing zone (R 2 = 0.34-0.65). Nevertheless, the capability of the MMU to detect the variations of personal exposures to O 3 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 copollutants.
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