Abstract

OLUTOLA, Bukola G  and  WICHMANN, Janine. Does apparent temperature modify the effects of air pollution on respiratory disease hospital admissions in an industrial area of South Africa?. Clean Air J. [online]. 2021, vol.31, n.2, pp.1-11. ISSN 2410-972X.  http://dx.doi.org/10.17159/caj/2021/31/2.11366.

BACKGROUND: Temperature and air pollution are often treated as separate risk factors and very few studies 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 admissions 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. Ambient NO₂, SO₂, PM, PM₂₅, 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). Days were classified as warm (Tapp>75^th percentile), cold (Tapp<25^th percentile) and normal (Tapp 25^th-75^th percentile. RESULTS: Of the 14 568 RD admissions, approximately an equal number of females and males were admitted. The average daily NO₂, SO₂, PM₂₅ and PM₁₀ levels were 12.4 μg/m³, 8.5 μg/m³, 32.3 μg/m³ and 68.6 μg/m³, respectively. Overall, a 10 μg/m³ increase in SO₂ on warm days was associated with an increase in RD hospital admissions: 8.5% (95% Conf. Int: 0.4%, 17.2%) and 8.4% (95% Conf. Int: 0.3%, 17.1%) after adjustment for PM₂₅ and PM, respectively. However, increasing PM₂₅ or PM₁₀ levels was associated with an increase in RD hospital admissions on normal days,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 PM₂₅ (6.5%; 95% Conf.Int: 0.9%, 12.4%) or PM₁₀ (5.5%; 95% Conf.Int: 0.3%, 11.1%. CONCLUSIONS: These results indicate that the risk of RD hospital admission due to ambient air pollution exposure is different on cold, normal and warm days in Secunda.

Keywords : Particulate matter; SO₂; apparent temperature; respiratory disease; hospital admissions; South Africa; case-crossover.

        · text in English     · English ( pdf )