Joint Monitoring and Early Warning of SARS-CoV-2 in Outdoor PM_2.5 and Wastewater

Background: Fine particulate matter (PM_2.5) and wastewater may carry severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and provide early signals for coronavirus disease 2019 (COVID-19) surveillance. This study investigated environmental factors affecting SARS-CoV-2 distribution in PM_2.5 and wastewater in Fuzhou. Methods: PM_2.5 and wastewater samples collected from January to December 2023 were tested for SARS-CoV-2 RNA using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Associations between air pollutants and meteorological factors were analyzed using generalized additive models (GAMs) and distributed lag nonlinear models (DLNMs). Results: SARS-CoV-2 was detected in 45.9% of PM_2.5 samples. PM_2.5 viral concentrations were positively associated with CO, PM_2.5, and atmospheric pressure, and negatively associated with temperature and sunshine duration. Wastewater viral concentrations were positively associated with relative humidity and precipitation and negatively associated with NO₂ and SO₂. PM_2.5 signals showed the strongest lag effect at approximately 2 days, while wastewater signals peaked at lag 0. The lag effect herein describes the time interval between environmental SARS-CoV-2 signals and predicted COVID-19 outpatient cases. Elderly populations showed higher environmental sensitivity, with sex-specific differences observed. Conclusions: SARS-CoV-2 signals in PM_2.5 and wastewater reflected COVID-19 trends. Integrated multi-media monitoring may improve early warning and support targeted public health interventions.