PM10 Element Distribution and Environmental-Sanitary Risk Analysis in Two Italian Industrial Cities

In this work, an evaluation of the air of two Italian industrial cities, Turin and Biella, has been performed to identify the main sources affecting its quality and to evaluate its evolution along 15 years. These two cities are placed at the border of the Po valley, one of the most polluted areas of Europe, and the automotive and textile industries have been their main economic sectors. The elemental analysis of the PM10 collected there in 2007 has been performed by ICP-MS and ICP-AES. The results identify the urban activities and the soil/road dust resuspension as the main sources of metals. Biella was overall less polluted in PM10 than Turin, probably because of its smaller size, its smaller traffic volume, and the lower number of industries. However, the limit value imposed by the European legislation for daily average PM10 mass concentration (50 μg m−3) was frequently exceeded in the collected samples: 22% and 50%, respectively for Biella and Turin. The concentration of specific toxic metals regulated by Italian legislation was never higher than the limit value for Cd (4 ng m−3) and Pb (0.5 μg m−3), whereas it was exceeded for Ni (20 ng m−3) in 22% of the samples from Turin and only in the 5% of those from Biella. In the same way, the risk analysis, performed using the target hazard quotient (THQ), calculated for children and adult populations, did not reveal warning values. Only for Cd in children were concerning values found (median THQ = 4.9). Element concentrations showed a seasonal trend, with higher values in November and December due to a combination of stable atmospheric conditions and strengthening of anthropic sources (e.g., combustion for heat generation). Finally, data concerning the amount of Cd, Ni, and Pb in the atmosphere provided by the regional agency for environmental protection (ARPA Piedmont) have been used to follow the evolution of these elements from 2007 to 2021 in the two cities. The data reveal a significant reduction of the concentrations of all considered metals in all the sites (higher than 50%), however maintaining the seasonal variability observed in PM10 samples of 2007, with higher concentrations during the cold months and lower concentrations during the summer.