Winter-spring droughts exacerbated PM_2.5-O₃ compound pollution? Evidence from China

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Climate Change Impact

Background:

• Global climate change is increasing drought frequency.
• Droughts critically impact air quality, necessitating quantitative evaluation.
• Understanding drought's effect on compound pollution is vital for mitigation.

Purpose of the Study:

• To quantitatively assess the 2023 winter-spring drought's impact on PM2.5 and O3 compound pollution.
• To identify the driving factors behind drought-induced air pollution increases.
• To provide insights for managing compound pollution under abnormal weather conditions.

Main Methods:

• Utilized augmented synthetic control method for impact assessment.
• Employed mediation effect model to analyze driving factors.
• Analyzed Chinese prefecture-level city data for PM2.5 and O3 variations.

Main Results:

• Drought periods showed significant increases in monthly averaged and diurnal PM2.5 and O3 levels.
• The 2023 drought caused substantial PM2.5 and O3 increases in Yunnan and Guizhou provinces.
• Increased temperature, decreased precipitation, and lower relative humidity were identified as primary drivers.

Conclusions:

• The winter-spring drought exacerbated PM2.5-O3 compound pollution.
• Meteorological factors like temperature and humidity play crucial roles in drought-related air pollution.
• Findings offer new perspectives for preventing compound pollution during extreme weather events.