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Abstracts of the 2019 Annual Conference of the International Society for Environmental Epidemiology, August 25-28 2019, Utrecht, the Netherlands

Effect modification of temperature on air pollution associated with hospital admission for respiratory diseases in Cape Town, South Africa

C, Lokotola1; J, Wichmann1; C, Wright2

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Environmental Epidemiology: October 2019 - Volume 3 - Issue - p 249
doi: 10.1097/01.EE9.0000608628.89964.ea
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PDS 72: Environmental health issues in LMIC, Exhibition Hall (PDS), Ground floor, August 28, 2019, 10:30 AM - 12:00 PM

Background: Global warming is impacting ambient temperature with subsequent increased risks for adverse human health impacts. Temperature and air pollution are often treated as separate risk factors and few studies have investigated effect modification by temperature on the association between air pollution and human health outcomes in Africa.

Methods: Individual level respiratory disease (ICD10: J00-J99) hospital admission data for 1 January 2011 to 31 October 2016 were obtained from seven private hospitals located in Cape Town, South Africa. NO2, SO2, PM10, temperature (converted to Apparent Temperature, Tapp) and relative humidity data for 2011 to 2016 were obtained from the South African Weather Services and the City of Cape Town. A case-crossover epidemiological study design was applied. The average air pollutant level on the day and the day before respiratory disease hospital admission (Lag0-1) was investigated. Models were adjusted for confounders. Days with Tapp below and above the median value were classified as cold and warm days, respectively.

Results: Stratified analysis showed higher modification of air pollution effect on hospital admission for respiratory disease when the ambient temperature increases. Warmer days indicated strong modification effect for PM10: 5.4% (3.3%, 7.6%), NO2: 16.1% (11.1%, 21.4%) and SO2: 17.5% (11.2%, 24.0%). The interaction effect between temperature and air pollution was higher during warm days. Higher modification effect occurred in ages < 65 years old for hospital admission for respiratory disease.

Conclusion: The findings are important to direct future research and to inform public health interventions.

Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of Environmental Epidemiology. All rights reserved.