Fine particulate matter (PM2.5) in China at a city level

TLDR

PM 2.5 concentrations are generally higher in northern China than in the south because of larger emissions and unfavorable meteorological conditions for dispersion. This study presents one of the first long‑term datasets summarizing one‑year PM 2.5 concentrations from 190 Chinese cities. The dataset was compiled from continuous monitoring across 190 cities over a full year. Only 25 of 190 cities meet national standards, the population‑weighted mean PM 2.5 is 61 µg/m³—about three times the global mean—while the pollutant shows pronounced seasonal peaks in winter, spring, and autumn, and diurnal lows in the afternoon and highs in the evening, with an afternoon peak in the PM 2.5‑to‑CO ratio indicating secondary formation.

Abstract

Abstract This study presents one of the first long term datasets including a statistical summary of PM 2.5 concentrations obtained from one-year monitoring in 190 cities in China. We found only 25 out of 190 cities could meet the National Ambient Air Quality Standards of China and the population-weighted mean of PM 2.5 in Chinese cities are 61 μg/m 3 , ~3 times as high as global population-weighted mean, highlighting a high health risk. PM 2.5 concentrations are generally higher in north than in south regions due to relative large PM emissions and unfavorable meteorological conditions for pollution dispersion. A remarkable seasonal variability of PM 2.5 is observed with the highest during the winter and the lowest during the summer. Due to the enhanced contributions from dust particles and open biomass burning, high PM 2.5 abundances are also found in the spring (in Northwest and West Central China) and autumn (in East China), respectively. In addition, we found the lowest and highest PM 2.5 often occurs in the afternoon and evening hours, respectively, associated with daily variation of the boundary layer depth and anthropogenic emissions. The diurnal distribution of the PM 2.5 -to-CO ratio consistently displays a pronounced peak during the afternoon periods, reflecting a significant contribution of secondary PM formation.