A global meta-analysis of particulate and gaseous air pollutants in relation to COVID-19 mortality and hospitalization

Behrooz  Karimi; Maedeh Moradi  Farahani

doi:10.18502/japh.v10i4.20620

Behrooz Karimi Department of Environmental Health Engineering, Health Faculty, Arak University of Medical Sciences, Arak, Iran
Maedeh Moradi Farahani Department of Environmental Health Engineering, Health Faculty, Arak University of Medical Sciences, Arak, Iran

DOI: https://doi.org/10.18502/japh.v10i4.20620

Keywords: Air pollutants; COVID-19 mortality; COVID-19 hospitalization; Meta analysis

Abstract

A growing body of evidence implicates ambient air pollution in the exacerbation of clinical outcomes after SARS-CoV-2 infection. To synthesize this evidence, we performed a global systematic review and meta-analysis to precisely quantify the associations between exposure to specific atmospheric contaminants and the subsequent risks of COVID-19-related mortality and hospital admission.

Our methodology adhered to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) framework, involving a comprehensive search of scientific databases for literature published until the end of August 2025. From this search, 44 publications were deemed eligible for inclusion. We employed random-effects models to compute summary Risk Ratios (RRs) representing the change in health risk per 1 µg/m³ increment in atmospheric pollutant concentration. Our findings indicate that long term exposure to fine Particulate Matter (PM2.5), coarse Particles (PM₁₀), Nitrogen dioxide (NO₂), and Sulfur dioxide (SO₂) significantly increased the likelihood of fatal outcomes from COVID-19. The respective pooled RRs were 1.046 (95% CI: 1.031–1.062), 1.079 (95% CI: 1.005–1.154), 1.017 (95% CI: 1.004–1.029), and 1.077 (95% CI: 1.021– 1.133). Acute exposures to ambient PM2.5 and NO₂ concentrations were similarly associated with increased mortality, demonstrating risk ratios of

1.043 (95% CI: 1.033–1.053) and 1.033 (95% CI: 1.019–1.048) respectively per 1 µg/m³ increment. Additionally, both acute and chronic exposures to PM2.5, PM₁₀, and NO₂ showed significant associations with higher COVID-19 hospitalization rates.

This meta-analysis provides robust quantitative suggestion that ambient PM2.5, PM10, NO₂, and SO₂ are significant and modifiable risk factors for severe COVID-19 outcomes. These results emphasize the critical need for enhanced air quality standards as a fundamental element of public health policy to alleviate the impact of COVID-19 and bolster defenses against forthcoming respiratory epidemics.