Impacts of urbanization and long-term meteorological variations on global PM and its associated health burden.

PM pollution has adverse health effects on humans. Urbanization and long-term meteorological variations play important roles in influencing the PM concentration and its associated health effects. Our results indicate that the urbanization process can enhance the PM concentration globally. The PM-caused mortality density (deaths/100 km) is also positively correlated with the urbanization degree in both developed and developing countries. The results from machine learning technique revealed that the meteorology-driven variation in PM-caused health burden has increased with the increase in the urbanization degree from 1980 to 2018, suggesting that residents living in urban areas are more vulnerable to experiencing unfavorable meteorological conditions (e.g. low wind speed and planetary boundary layer height). The maximum difference in PM-caused mortality due to the variation in annual meteorological conditions (between 2013 and 1986) was 270 600 (196 800-317 900). Our findings indicate an urgent need to understand the driving force behind the appearance of unfavorable meteorological situations and propose suitable climate mitigation measures.