Spatiotemporal variations and risk assessment of ambient air O 3 , PM 10 and PM 2.5 in a coastal city of China.

Rapid industrialization and urbanization has created significant air pollution problems that have recently begin to impact the lives and health of human beings in China. This study systematically investigated the spatiotemporal variations and the associated health risks of ambient O ₃ , PM ₁₀ and PM _2.5 between 2016 and 2019. The relationships between the target air pollutants and meteorological conditions were further analyzed using the Spearman rank correlation coefficient method. The results demonstrated that the annual mean concentrations of PM ₁₀ and PM _2.5 experienced a decreasing trend overall, and PM _2.5 significantly decreased from 1.54 μg/m ³ in 2016 to 1.48 μg/m ³ in 2019. In contrast, the annual mean concentrations of O ₃ were nearly constant during the study period with a slight increasing trend. The pollutants exhibited different seasonal variations and cyclical diurnal variations. The most highest O ₃ pollution was seen in spring and summer, while spring and winter were the seasons with the most PM ₁₀ and PM _2.5 pollution. The highest concentrations of O ₃ appeared in periods of strong solar radiation intensity and photochemical reactions. The highest concentrations of PM ₁₀ and PM _2.5 appeared at commuting time. The pollutant concentrations were significantly affected by meteorological conditions. Finally, the non-carcinogenic risks from exposure to O ₃ , PM ₁₀ and PM _2.5 were at an acceptable level (HI < 0.96) and O ₃ accounted for ~50% of the total non-carcinogenic risks. However, PM _2.5 posed highly carcinogenic risks (2.5 × 10 ^-4  < CR < 1.6 × 10 ^-1 ) and O ₃ exposure showed high potential ecological impacts on vegetation (AOT40: 23.3 ppm-h; W126: 29.0 ppm-h).
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