Benchmark study on fine-mode aerosol in a big urban area and relevant doses deposited in the human respiratory tract

It is well-known that the health effects of PM increase as particle size decreases: particularly, great concern has risen on the role of UltraFine Particles (UFPs). Starting from the knowledge that the main fraction of atmospheric aerosol in Rome is characterized by significant levels of PM2.5 (almost 75% of PM10 fraction is PM2.5), the paper is focused on submicron particles in such great urban area. The daytime/ nighttime, work-/weekdays and cold/hot seasonal trends of submicron particles will be investigated and discussed along with NOx and total PAH drifts demonstrating the primary origin of UFPs from combustion processes. Furthermore, moving from these data, the total dose of submicron particles deposited in the respiratory system (i.e., head, tracheobronchial and alveolar regions in different lung lobes) has been estimated. Dosimeter estimates were performed with the Multiple-Path Particle Dosimetry model (MPPD v.2.1). The paper discusses the aerosol doses deposited in the respiratory system of individuals exposed in proximity of traffic. During traffic peak hours, about 6.6 1010 particles are deposited into the respiratory system. Such dose is almost entirely made of UFPs. According to the greater dose estimated, right lung lobes are expected to be more susceptible to respiratory pathologies than left lobes.