Association of Particulate Matter (PM2.5) With COVID-19 Infection and Mortality in Low-and Middle-income Asian...

Low-income and middle-income countries in Asia bear a disproportionate burden of particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) pollution, yet data remain scarce. This systematic review and meta-analysis aimed to quantify the association between PM2.5 exposure and the risks of coronavirus disease 2019 (COVID-19) infection and mortality in this vulnerable region.

A systematic search was conducted in PubMed, Scopus, and other major databases for studies published up to December 31, 2024. We included observational studies reporting associations between PM2.5 and COVID-19 outcomes in low-income and middle-income Asian countries. Pooled effect sizes and 95% confidence intervals (CIs) were calculated using a random-effects model. The study was registered with PROSPERO (CRD42022316008).

Fourteen studies met the inclusion criteria. Separate analyses demonstrated statistically significant positive associations between PM2.5 exposure and COVID-19 infection for both short-term exposure (pooled risk ratio [RR], 1.12; 95% CI, 1.07 to 1.18) and long-term exposure (pooled RR, 1.41; 95% CI, 1.28 to 1.56). For mortality, the analysis identified a statistically non-significant positive association with short-term exposure (pooled RR, 1.37; 95% CI, 0.80 to 2.33). Substantial heterogeneity was observed across all analyses (I²>75%); however, sensitivity analyses confirmed that the findings for infection were robust.

Our findings provide robust evidence that PM2.5 exposure is a significant risk factor for COVID-19 infection in low-income and middle-income Asian countries. The available evidence was insufficient to establish a clear association with mortality. These results underscore the urgent need for strengthened air quality control policies as a critical component of public health strategies to mitigate the burden of respiratory pandemics.