[Spatiotemporal Distribution and Health Impacts of PM_2.5 and O₃ in Beijing, from 2014 to 2020]

In China, fine particulate matter (PM_2.5) and tropospheric ozone (O₃) have become major air pollutants that threaten human health. Since 2013, the government has strengthened air pollution controls in Beijing and achieved significant effects. A spatial-temporal analysis was conducted of the distribution and health impacts of PM_2.5 and O₃ in Beijing, using data collected from 34 air quality monitoring sites between 2014 and 2020. In 2014, the annual average PM_2.5 and seasonal (April to September) average of daily one-hourly maximum O₃ concentrations (O_{3_max}) were 92.0 μg·m^-3 and 81.9 nmol·mol^-1, respectively. From 2014 to 2020, annual average PM_2.5 decreased at a rate of 7.5 μg·m^-3. However, there was no significant difference in O_{3_max} over the years. The concentrations of PM_2.5 were highest in December and January (in winter) and lowest in August (in summer). On the contrary, O_{3_max} was highest in June. The diurnal variations of PM_2.5 were affected by meteorological conditions and emission sources, and maximum concentrations occurred between 22:00 to 00:00, while minimum concentrations occurred between 14:00 to 16:00. The concentration of O_{3_max} showed an opposite pattern, with minimum vales occurring at 07:00 and maximum values occurring in the afternoon. The spatial distribution of PM_2.5 showed similar patterns in 2014 and 2019, with the south of Beijing exhibiting the highest concentrations, and the north the lowest. The concentration of O_{3_max} was higher in suburban areas than in traffic areas. In terms of health impacts, 1580 cases of cardiovascular disease and 821 of respiratory disease were attributed to PM_2.5 in 2014, while 2180 cases of respiratory disease were attributable to O₃ in 2014. In 2019, mortalities attributable to PM_2.5 had decreased by 50% compared to 2014. While the number of disease cases attributable to O₃ were similar in 2014 and 2019. the results indicate that PM_2.5 pollution in Beijing has been successfully controlled, while O₃ pollution has become more severe, and was the primary air pollutant threatening human health in 2019. Therefore, the synchronous control of PM_2.5 and O₃ should be implemented in the future.