Spatiotemporal Distribution of PM 2.5 and O 3 and Their Interaction During the Summer and Winter Seasons in Beijing, China

This study analyzed the spatiotemporal variations in PM 2.5 and O 3 , and explored their interaction in the summer and winter seasons in Beijing. To this aim, hourly PM 2.5 and O 3 data for 35 air quality monitoring sites were analyzed during the summer and winter of 2016. Results suggested that the highest PM 2.5 concentration and the lowest O 3 concentration were observed at traffic monitoring sites during the two seasons. A statistically significant ( p < 0.05) different diurnal variation of PM 2.5 was observed between the summer and winter seasons, with higher concentrations during daytime summer and nighttime winter. Diurnal variations of O 3 concentrations during the two seasons showed a single peak, occurring at 16:00 and 15:00 in summer and winter, respectively. PM 2.5 presented a spatial pattern with higher concentrations in southern Beijing than in northern areas, particularly evident during wintertime. On the contrary, O 3 concentrations presented a decreasing spatial trend from the north to the south, particularly evident during summer. In addition, we found that PM 2.5 concentrations were positively correlated ( p < 0.01, r = 0.57) with O 3 concentrations in summer, but negatively correlated ( p < 0.01, r = −0.72) with O 3 concentrations in winter.