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 article focuses on air pollution in specific urban microenvironments and conditions characterized by high relative concentration levels and by possible risk to human health. For this reason, monitoring of particle number concentration (PNC) with a wide, size-resolved particle-size range, and CO (an indicator of combustion sources, e.g., traffic), was performed in a variety of microenvironments. Concentrations of ultrafine particles (UFPs), size-fractionated particulate matter (PM), and carbon monoxide (CO) were measured in the central area of Milan over three-week-long periods, one each during summer, autumn, and winter, with three monitoring sessions per day. Experimental data were collected continuously during each monitoring period along an established urban pathway. To assess the relevance of time and spatial factors affecting atmospheric concentrations of UFPs, PM, and CO data were collected while walking or moving by different private and public means of transport. Measurements were divided on the basis of different microenvironments (MEs), seasons, days of the week, and periods of the day. Data analysis shows statistically significant differences across MEs and monitoring periods. The highest measured median concentrations and data variability were observed for busy streets, walking or moving by motorized vehicle (CO, UFP) and in metro trains (PM); the lowest concentrations were observed in park areas and in indoor environments. The highest concentrations were measured during working day morning monitoring sessions. Regarding seasonal variation, UFP, PM, and CO showed different patterns: the highest median concentrations were observed in summer for CO, and in autumn and winter for the UFP and PM. Appreciable differences among all MEs and monitoring periods were observed: concentration patterns and variations appear related to typical sources of urban pollutants (traffic), proximity to sources, and time of day. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing Table VI: Tau b (Kendall) index for non-parametric correlation tau test.].

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.