Aerosol pollution in urban environments has been recognized to be responsible of important pathologies of the cardiovascular and respiratory systems, it has also been associated to increased mortality and hospital admissions. New regulationsstate that for fine particulate matter (PM2.5) there is yet no identifiable threshold below which PM2.5 would not pose a risk. Therefore, a general reduction of its concentrations in the urban background should be pursued to ensure that large sections of the population benefit from improved air quality.More recently, the International Agency for Research on Cancer (IARC) has considered outdoor pollution as a leading environmental cause of cancer deaths. Furthermore, particulate matter has been classified as carcinogenic to humans (Group 1). Within this context, the importance of the measurements of aerosol size distribution resides in that the doses deposited in the human respiratory system strictly depend on the particle sizes. In this perspective, great attention has been addressed to Ultra Fine Particles (UFPs,< 100 nm), since they efficiently penetrate into the respiratory system and are capable of traslocating from the airways into the blood circulation.Many studies show that particle toxicity increases with decreasing their size, emphasizing the roleofsubmicrometric particles, in particular of ultrafine particles (< 100 nm). In fact, particles greater than 2.5 ìm are quickly removed through dry and wet deposition on the time scale of hours whereas submicrometer particles may reside in atmosphere for weeks, penetrate in indoor environment and be long-range transported. High aerosol size resolution measurements are important for a correct assessment of the deposition efficiency in the human respiratory system as well as time resolution is another important requisite. Starting from such considerations, time resolved aerosol particle number size distributions have been measured in downtown Rome. FMPS and SMPS measurements have been carried out at the INAIL’s Pilot Station, located in downtown Rome, in anarea characterized by high density of autovehicular traffic. The two instruments have allowed to investigate deeply the urban aerosol in the range 5.6-560 nm and 3.5-117 nm, respectively. In particular, the FMPS measurements have confirmed the interpretation about the transition phenomena in the time interval of few seconds, time scale typically associated with the emission of gasoline and diesel. In downtown Rome the hourly-average size distribution are bimodal or trimodal with maxima at about 5-15 nm, 20-30 nm and 70-100 nm. Particle formation in the nucleation mode was favored in periods with high radical oxidative activity. Furthermore, moving from these data the total dose of particles and ultrafine particles deposited in the regions of the respiratory system (head, tracheobronchial and alveolar in the different lung lobes,have been estimated. Dosimetry estimates were performed with the Multiple-Path Particle Dosimetry model (MPPD v.2.1). Calculations were carried out by means of the stochastic lung model (60 percentile), because it provides a more realistic lung geometry than symmetric models. Doses are trheported both as number of particles deposited for each tidal volume of air inhaled (instant doses) and as number of particles deposited at the end of an exposure period (cumulative doses). This lecture will discuss the aerosol doses deposited in the respiratory system of individuals exposed in proximity of traffic. During traffic peak hours, about 6.6×10 particles are deposited into the respiratory system. Such dose is almost entirely made of UFPs. A1c0cording to the greater dose estimated, right lung lobes are expected to be more susceptible to respiratory pathologies than left lobes.
|Titolo:||Dynamic and behavior of ultrafine particles in urban atmosphere: toxicity and deposition in human respiratory system|
AVINO, Pasquale (Corresponding)
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|