No abstract

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.

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.

This study presents a comparison between measured indoor concentrations in the study area and indoor air quality guideline criteria. Accordingly, particulate matter (PM) and NO₂ are identified as key pollutants that may pose health concerns. It is also found that indoor PM in residential units is mainly constituted by particles with aerodynamic diameters <0.5 μm, especially in winter. Risk mitigation strategies should be focused on the reduction in indoor levels of NO₂ and ultrafine and fine particles, both infiltrated from outdoors and generated by indoor sources.