دانلود رایگان مقاله تغلیظ تعداد ذرات در نزدیکی فرودگاه سیامپینو درشهر رم

abstract

Human exposure to ultrafine particles (UFP) has been postulated to be associated with adverse health effects, and there is interest regarding possible measures to reduce primary emissions. One important source of UFP are airport activities, with aircraft take-offs being the most relevant one. We implemented two measurement campaigns of total particle number concentrations (PNC), a proxy for UFP, near a medium-size airport in central Italy. One-minute PNC averages were collected on June 2011 and January 2012 concurrently with 30-min average meteorological data on temperature and wind speed/direction. Data on minute-specific take-offs and landings were obtained by the airport authorities. We applied statistical regression models to relate PNC data to the presence of aircraft activities while adjusting for time trends and meteorology, and estimated the increases in PNC ±15 min before and after take-offs and landings. We repeated the analyses considering prevalent wind direction and by size of the aircraft. We estimated PNC increases of 5400 particles/cm3 /minute during the 15 min before and after take-offs, with a peak of 19,000 particles/cm3 /minute within 5 min after take-offs. Corresponding figures for landings were 1300 and 1000 particles, respectively. The highest PNC estimates were obtained when the prevailing wind came from the runway direction, and led to estimated PNC increases of 60,000 particles/ cm3 /minute within 5 min after take-offs. No main differences were noted from the exhaust of different types of aircrafts. The area surrounding Ciampino airport is densely inhabited, raising concerns about the potential adverse effects of long-term and short-term exposure to airport-borne UFP. A close monitoring of airport activities and emissions is mandatory to reduce the public health impact of the airport on the nearby population.

4. Discussion and conclusions

We aimed at quantifying the contribution of aircraft activities to PNC concentrations in a medium-sized airport. Substantial increases of PNC values in the few minutes after take-offs, especially downwind, with small differences between large and small vehicles were estimated. In contrast, landings displayed only a modest contribution to ground-level PNC observations. This work is part of the SERA project, a study aimed at assessing the health impact of noise and air pollution among people living nearby six Italian airports (Ancona et al., 2014; Ancona and Forastiere, 2014). Land use regression models allowed us to describe the spatial distribution of NO2, benzene, toluene and acrolein concentrations, showing that small-scale spatial gradients were affected by local traffic while only a small fraction of the spatial variability could be attributed to airport related emissions (Gaeta et al., 2016). Moreover, high temporally resolved PNC data combined with radar tracks enabled us to estimate the direct contribution of LTO operations on PNC values in nearby areas, a task otherwise impossible with hourly or daily averaging periods, since airport contributions might be masked in the complex mix of urban activity emissions (Di Menno di Bucchianico et al., 2014). These observations raised the need to design a further study where a more flexible approach, distributed-lag regression models, could provide a qualitative and quantitative estimation of the contribution of aircraft emissions to UFP concentrations near the Ciampino airport.