Ambient air pollution and cardiorespiratory outcomes amongst adults residing in four informal settlements in the Western Province of South Africa

Abstract

BACKGROUND AND AIM: Despite the majority of ambient air pollution-related deaths occurring in low-and middle-income countries, most of the studies that have investigated the relationship between ambient air pollution and cardiorespiratory outcomes were not conducted in Africa. This study investigated the relationship between ambient air pollution exposure and self-reported cardiorespiratory outcomes amongst adults residing in four informal settlements of the Western Province of South Africa. METHODS: A cross-sectional study comprising of 572 adults from four informal settlements (Khayelitsha, Marconi-Beam, Oudtshoorn and Masiphumelele) in Western Cape, South Africa was conducted. The study made use of modelled exposure estimates using Land-Use Regression for particulate matter of aerodynamic diameter of 2.5µm (PM2.5) and nitrogen dioxide (NO2) at each participant’s home address. An adapted European Community Respiratory Health Survey and National Health and Nutrition Examination Survey questionnaire was used to collect data on self-reported cardiorespiratory outcomes and covariates. RESULTS:The median age of the participants was 40.7 years and 88.5% of the participants were female. The median NO2 level was 19.7 µg/m3 with interquartile range (IQR): 9.64 – 23.7 and PM2.5 level, 9.7 µg/m3 (IQR: 7.3 – 12.4). An interquartile range increase of 5.12 µg/m3 in PM2.5 was associated with an increase prevalence of self-reported chest-pain [1.38 (95%CI: 1.06 - 1.80)] adjusting for NO2, and other covariates. CONCLUSIONS:The study found preliminary evidence of a possible association between annual ambient PM2.5 exposure and chest-pain (a crude proxy of angina-related pain), even at levels below both WHO Air Quality Guidelines and the South African National Ambient Air Quality Standards. However, the results should be interpreted cautiously due to the self-reported nature of the outcome measure, small sample size and the cross-sectional design of the study. KEYWORDS: Air Pollution, Cardiovascular Diseases, Respiratory Diseases, Chemical Exposures, Asthma