Short-term exposure to airborne particulate matter and COVID-19 infection in South Korea

Abstract

BACKGROUND AND AIM: Coronavirus disease 2019 (COVID-19) has become a global public health problem. Previous studies have indicated that COVID-19 infection can occur through airborne transmission, and atmospheric particulate matter may favor the spread of the virus. This study aimed to explore the relationship between daily particulate matter ≤ 2.5 or 10 micrometers in diameter (PM2.5 or PM10) and daily COVID-19 confirmed cases in South Korea. METHODS: We obtained daily confirmed cases, PM concentrations, and meteorology in South Korea from the first occurrence on February 24 through December 31 in 2020. Using generalized additive model, we estimated relative risks (RRs) of COVID-19 new cases for a 10µg/m3 increase in PM averaged over the previous 1, 3, 5, 7, 10, 14, and 21 days after adjusting for a temporal trend, meteorology, new confirmed cases on the previous day, and day of week. Non-linear associations of the temporal trend and meteorology with new cases were assessed by using regression spline. In particular, we applied 35 degrees of freedom (df) to the temporal trend, which is larger than as used in previous studies to account for relatively short-term changes in new cases derived by people’s activity patterns. RESULTS:Although there was no evidence of the association of daily confirmed cases with recent exposures to PM2.5, we found the positive association with extended exposure for the previous 14 and 21 days (RR=1.13, 95% CI=1.01-1.27; 1.17, 1.04-1.3, respectively). These patterns were similar for PM10 (1.03, 0.95-1.12; 1.1, 1.00-1.2, respectively). The findings were also consistent with more or less adjustment for time in our sensitivity analysis. CONCLUSIONS:Our findings suggested that airborne particulate matter can accelerate risk of COVID-19 transmission in two or three weeks. Further studies should account for other transmission-related characteristics to confirm the association. KEYWORDS: Air pollution, short-term exposure, COVID-19 incidence