Ultrafine particle apportionment and exposure assessment in respect of linear and point sources

The effects of particulate matter on the environment and public health were widely studied in recent years but agreement amongst these studies on the relative importance of the particle size and its origin with respect to health effects is still lacking. Nevertheless, air quality standards are moving towards greater focus on the smaller particles. In industrialized areas, anthropogenic activities are a major contributor to the particle concentrations. Then, it is important to characterize the emission sources as well as the evolution of particle size distribution in the proximity of these emission points. In this study, the authors evaluated the particle concentration and size distribution at a downwind receptor site of a linear (a major highway) and point (waste incinerator plant) source in an area characterized by high anthropic environmental impact. The particle emissions of the incinerator under examination were characterized by using a Scanning Mobility Particle Sizer® (SMPS), an Aerodynamic Particle Sizer® (APS) Spectrometer, a Rotating Disk Thermodiluter and a Thermal Conditioner (Matter Engineering AG). As regards the linear source, concentrations were determined at increasing distances from the most important Italian road, the A1 highway. Particle number, surface and mass exponentially decreases away from the freeway, whereas particle number concentration measured at 400 m downwind from the freeway is indistinguishable from upwind background concentration. Annual mean values of 8.6x103 ± 3.7x102 particle cm‐3 and 31.1 ± 9.0 μg m‐3 were found for particle number and PM10 concentration, typical of a rural site. The particle apportionment and exposure assessment in respect of linear and point sources for ultrafine particles represent the major novelty of the present paper. The study here presented could be very important in developing appropriate management and control strategies for air quality in areas characterized by high anthropic pressure and to perform exposure assessment for populations involved.