Meteorological drivers of seasonal PM2.5 variability in selected Asian countries: A mini review

High concentrations of fine particulate matter significantly affect environmental quality and human health across Asia, driven by rapid urbanization, industrialization, and complex interactions with regional meteorology. Although numerous studies have examined meteorological impacts on PM 2.5 variability, most focus on individual variables or limited geographic domains, hindering a comprehensive regional understanding. This mini-review synthesizes literature on the influence of key meteorological factors – including temperature, precipitation, wind speed, relative humidity, and long-range atmospheric transport – on the seasonal variability of PM 2.5 across ten countries in South, East, Southeast and Central Asia. Temperature generally exhibits a negative relationship with PM 2.5 in winter, low-level temperature inversions, reduced planetary boundary-layer height, and atmospheric stagnation, resulting in seasonal concentration differences of 50–90% across the region. Precipitation primarily reduces PM 2.5 through wet scavenging, lowering the concentration by 50–80% on a seasonal basis. However, light rainfall under high humidity can increase PM 2.5 concentrations by up to 62% through enhanced secondary aerosol formation. Wind influences PM 2.5 level by dispersing local pollutants or increasing concentration through regional and transboundary transport. The relationship between relative humidity and PM 2.5 is highly nonlinear and threshold-dependent, with moderate humidity promoting hygroscopic growth and high humidity aiding wet removal and settling. Long-range atmospheric transport accounts for 53–85% of PM₂.₅ in receptor regions during dry and cold seasons, highlighting the limitations of national emission-control strategies in isolation. By providing a cross-country comparative synthesis and variable-specific summary, this review offers insights to support improved air-quality modeling, forecasting, and regional pollution mitigation policies across Asia.