Effect of short-term exposure to air pollution on daily cardio- and cerebro-vascular hospitalisations in areas with a low level of air pollution

Exposure to air pollution is associated with increased cardio- and cerebro-vascular diseases. However, the evidence regarding the short-term effect of air pollution on cardio- and cerebro-vascular hospitalisations in areas with relatively low air pollution levels is limited. This study aims to examine the effect of short-term exposure to different air pollutants on hospital admissions due to cardio- and cerebro-vascular diseases in rural and regional Australia with low air pollution. The study was conducted in five local Government areas of Hunter New England Local Health District (HNE-LHD). Hospitalisation data from January 2018 to February 2020 (820 days) were accessed from the HNE-LHD admitted patients’ dataset. Poisson regression model was used to examine the association between the exposure (air pollutants) and outcome variables (hospitalisation due to cardio- and cerebrovascular disease). The concentrations of gaseous air pollutants, Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2), Ozone (O3), Carbon Monoxide (CO), and Ammonia (NH3) were below national benchmark concentrations for every day of the study period. In single pollutant models, SO2 and NO2 significantly increased the daily number of cardio and cerebrovascular hospitalisations. The highest cumulative effect for SO2 was observed across lag 0-3 days (Incidence Rate Ratio, IRR: 1.77; 95% Confidence Interval, CI: 1.18-2.65; p-value: 0.01), and for NO2, it was across lag 0-2 days (IRR: 1.13; 95% CI: 1.02-1.25; p-value: 0.02). In contrast, higher O3 was associated with decreased cardio- and cerebro-vascular hospitalisations, with the largest effect observed at lag 0 (IRR: 0.94; 95% CI: 0.89-0.98; p-value: 0.02). In the multi-pollutant model, the effect of NO2 remained significant at lag 0 and corresponded to a 21% increase in cardio- and cerebro-vascular hospitalisation (95% CI: 1%-44%; p-value = 0.04). Thus, the study revealed that gaseous air pollutants, specifically NO2, were positively related to increased cardio- and cerebro-vascular hospitalisations, even at concentrations below the national standards.