Short-Term Joint Effects of PM, NO and SO on Cardio-Respiratory Disease Hospital Admissions in Cape Town, South Africa.

Background/aim: In sub-Sahara Africa, few studies have investigated the short-term association between hospital admissions and ambient air pollution. Therefore, this study explored the association between multiple air pollutants and hospital admissions in Cape Town, South Africa.

Methods: Generalized additive quasi-Poisson models were used within a distributed lag linear modelling framework to estimate the cumulative effects of PM, NO, and SO up to a lag of 21 days. We further conducted multi-pollutant models and stratified our analysis by age group, sex, and season.

Results: The overall relative risk (95% confidence interval (CI)) for PM, NO, and SO at lag 0-1 for hospital admissions due to respiratory disease (RD) were 1.9% (0.5-3.2%), 2.3% (0.6-4%), and 1.1% (-0.2-2.4%), respectively. For cardiovascular disease (CVD), these values were 2.1% (0.6-3.5%), 1% (-0.8-2.8%), and -0.3% (-1.6-1.1%), respectively, per inter-quartile range increase of 12 µg/m for PM, 7.3 µg/m for NO, and 3.6 µg/m for SO. The overall cumulative risks for RD per IQR increase in PM and NO for children were 2% (0.2-3.9%) and 3.1% (0.7-5.6%), respectively.

Conclusion: We found robust associations of daily respiratory disease hospital admissions with daily PM and NO concentrations. Associations were strongest among children and warm season for RD.