Influence of air pollution and climate variability on dengue in Singapore: a time-series analysis

The associations between respiratory and cardiovascular health outcomes with air quality have been well examined. Less conclusive are the studies assessing the relationship between air quality and dengue, a mosquito-borne illness which continues to pose risk to more than half the world's population. We examined this relationship in Singapore, a tropical city-state located in the South-East Asian region where the burden of dengue is among the highest across the globe. We analyzed the short-term associations between all laboratory-confirmed dengue reports and variations in PM_2.5, PM_10, CO, O₃, NO₂ and SO₂ in Singapore from 2009 to 2019 using the Distributed Lag Non-linear Model (DLNM) framework. PM_2.5 (RR_{90th percentile}: 1.28, 95% CI 1.11,1.49), PM₁₀ (RR_{90th percentile}: 1.30, 95% CI 1.12, 1.51), and CO (RR_90th percentile: 1.30, 95% CI 1.06, 1.61), were positively associated with dengue up to a period of 48 days with observed maximum threshold effects, while O₃ and NO₂ were negatively associated with dengue. There was a positive, non-linear association between ambient temperature and dengue. We observed strong evidence of ambient temperature modifying the association between particulate matter and dengue risk. Variations in the concentrations of these air pollutant types may inform short-term dengue control resource augmentation plans.