Does apparent temperature modify the effects of air pollution on respiratory disease hospital admissions in an industrial area of South Africa?

Abstract

Background: Temperature and air pollution are often treated as separate risk factors and very few studies have investigated effect modification by temperature on air pollution, and the impact of this interaction on human health in Africa. This study therefore investigated the modifying effects of temperature on the association between air pollution and Respiratory disease (RD) hospital admission in South Africa.
 Methods: RD admission data (ICD10 J00-J99) were obtained from two hospitals located in Secunda, South Africa beween 1 January 2011 to 31 October 2016. NO2, SO2, PM10, PM2.5, temperature and relative humidity data were obtained from the South African Weather Services. A case-crossover epidemiological study design was applied and lag0-1 was used. Models were adjusted for public holidays and Apparent Temperature (Tapp). Tapp was classified as warm (Tapp>75th percentile), cold (Tapp<25th percentile) and normal (Tapp 25th-75th percentile).
 Results: Of the 14 568 RD admissions, approximately equal number of females and males were admitted. The average daily NO2, SO2, PM2.5 and PM10 levels were 12.4 μm/m3, 8.5 μm/m3, 32.3 μm/m3 and 68.6 μm/m3, respectively. Overall, a 10 μm/m3 increase in SO2 on warm days was associated with an increase in RD hospital admissions among the patients by 8.5% (95% Conf. Int: 0.4%, 17.2%) and 8.4% (95% Conf. Int: 0.3%, 17.1%) after adjustment for PM2.5 and PM10 respectively. However, increasing PM2.5 or PM10 by 10 μm/m3 was associated with an increase in RD hospital admissions when the temperature was normal after adjusting for SO2. On cold days there were significant associations between the SO2 and RD admissions among the 0-14 year age group after adjusting for either PM2.5 (6.5%; 95% Conf.Int: 0.9%, 12.4%) or PM10 (5.5%; 95% Conf.Int: 0.3%, 11.1%).
 Conclusions: SO2 was affected by extremes of temperature while the particulate matters had effect on RD admission during normal temperature in Secunda.

Temperature modifies the association between air pollution and respiratory disease hospital admissions in an industrial area of South Africa: The Vaal Triangle Air Pollution Priority Area

“…Moderate Tapp days were those equal or higher than the 25 th percentile level, but lower or equal to the 75 th percentile level. A similar approach was followed in other studies (Chen et al 2017;Li et al 2017, Lokotola et al 2020Olutola and Wichmann, 2021;Shirinde and Wichmann, 2022).…”

“…i.e. mean of lag0 (same day of exposure as day of hospitalisation) and lag 1 (day prior to day of hospitalisation) (Chen et al, 2017;Li et al, 2017, Song et al, 2017, Lokotola et al, 2020Olutola and Wichmann, 2021; 6) Bongani Mabaso Eco Park, (7) AJ Jacobs, (8) Leitrim. Thabethe et al 2021;Shirinde and Wichmann, 2022;Adebayo-Ojo et al, 2022).…”

“…The associations between air pollution and respiratory disease hospital admissions were investigated with the case-crossover epidemiological design, as done in numerous other studies globally (Chen et al, 2017;Li et al, 2017;Song et al, 2017) and in South Africa (Lokotola, Wright and Wichmann, 2020;Olutola and Wichmann, 2021;Thabethe, Voyi & Wichmann 2021;Wichmann &Voyi 2012, Shirinde and.…”

“…The South African Weather Services (SAWS) manages the data that are deposited in the South African Air Quality Information System. The air pollution data source is the same as the very large study of 682 cities (Liu et al, 2019) and other local studies (Adebayo-Ojo et al, 2022;Olutola andWichmann, 2021, Shirinde and. A network of six air pollution monitors were assigned to the VTAPA (South African Air Quality Information System 2022) and these continuously assess realtime concentrations of the criteria air pollutants using equivalent methods of the United States Environmental Protection Agency and in accordance with ISO 17025 guidelines (National Environmental Management: Air Quality Act, 2004) (Figure 1).…”

“…Most of these studies focused on cause-specific mortality, such as respiratory, cerebrovascular diseases and specific cardiovascular diseases. Fewer studies globally investigated cause-specific hospital admissions (Abed Al Ahad et al, 2020;Lokotola et al, 2020;Olutola and Wichmann, 2021;Areal et al, 2022). The evidence so far is ambiguous and studies are lacking in LMIC.…”