Assessment of Air Pollution, by the Urban Traffic, in University Campus of Bucharest

Abstract

This study aims to measure traffic-related air pollution of vehicles with internal combustion, the main source of emissions of BTEX, organic compounds and NOx, NO2, NO, O3, CO, SO2, PM10 and PM2.5, inorganic compounds, in three sites of the University campus, surrounded by residential areas. According to the University data, around 8000 students are being exposed daily to the measured level of pollution, in all 3 studied places of campus. A mobile laboratory was used, which continuously measures above mentioned pollutants and mete-orological parameters. The diurnal variation of BTEX, in a sunny and rainy day showed two peaks of BTEX concentration in the morning and evening. In the rainy days, the non-polar (hydrophobic) compounds as BTEX are mechanically trained by rain into the ground, where either they enter into the groundwater, or volatilized and re-enter in the air. Particulate matter such as PM10 and PM2.5 is, in a large part, carried by the rain into the soil. The polar compounds (hydrophilic, NOx, SO2) dissolves in the rainwater and are absorbed in the soil (increasing soil acidity) and evaporated towards the clouds (leading to acid rain). In our study, BTEX compounds removed by the rain varied between 62% - 75%, NOx and SO2, 80% and 77% respectively. Particulate matters were washed out up to 68% for PM10, and 42% for PM2.5. In the sunny days the air pollution with measured concentrations of O3 (121.66 ± 7.02, 123.56 ± 4.89 μg/m3) remained for 7 hours close to the limit value (120 μg/m3). The maximum of solar radiation, with corresponding low concentrations in NOx and xylene, corresponds to photochemical reactions in the atmosphere, generating photochemical smog. In a sunny day and high traffic, we found the maximum value 5.4 μg/m3 for benzene, for 30 min., a known human carcinogen, exceeding the annual limit value de 5 μg/m3. The average background, from benzene, in three University campuses daily visited by around 8000 students was 0.97 μg/m3, exposed to 1.46 μg/m3 and the cancer risk is 1/100,000.