Causal relationship between particulate matter 2.5 (PM(2.5)), PM(2.5) absorbance, and COVID-19 risk: A two-sample Mendelian randomisation study

BACKGROUND: Several observational studies reported on the association between particulate matter ≤2.5μm (PM(2.5)) and its absorbance with coronavirus (COVID-19), but none use Mendelian randomisation (MR). To strengthen the knowledge on causality, we examined the association of PM(2.5) and its absorbance with COVID-19 risk using MR. METHODS: We selected genome-wide association study (GWAS) integration data from the UK Biobank and IEU Open GWAS Project for two-sample MR analysis. We used inverse variance weighted (IVW) and its multiple random effects and fixed effects alternatives to generally predict the association of PM(2.5) and its absorbance with COVID-19, and six methods (MR Egger, weighted median, simple mode, weighted mode, maximum-likelihood and MR-PRESSO) as complementary analyses. RESULTS: MR results suggested that PM(2.5) absorbance was associated with COVID-19 infection (odds ratio (OR) = 2.64; 95% confidence interval (CI) = 1.32-5.27, P = 0.006), hospitalisation (OR = 3.52; 95% CI = 1.05-11.75, P = 0.041) and severe respiratory symptoms (OR = 28.74; 95% CI = 4.00-206.32, P = 0.001) in IVW methods. We observed no association between PM(2.5) and COVID-19. CONCLUSIONS: We found a potential causal association of PM(2.5) absorbance with COVID-19 infection, hospitalisation, and severe respiratory symptoms using MR analysis. Prevention and control of air pollution could help delay and halt the negative progression of COVID-19.