Apparent temperature as a modifier of the effects of air pollution on respiratory disease hospital admissions in Secunda, South Africa

Abstract

TPS 681: Short-term health effects of air pollutants 1, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Due to climate change, an increase of 34°C in ambient temperature is projected along the South African coast and 6-7°C inland during the next 80 years. Very few studies in Africa investigated effect modification by a temperature indicator (e.g. apparent temperature, Tapp) on the human health effects of air pollution. Methods: Respiratory disease (RD) admission data (ICD10 J00-J99) were obtained from MediClinic for the two hospitals located in Secunda; after ethics approval. The study period is 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. The present study focused on lag0-1; as most other studies. Models were adjusted for public holidays and Tapp. Days with Tapp below and above/equal the median (14.9C) were classified as cold and warm days, respectively. Results: Of the 14 568 RD admissions, approximately equal number of females and males were admitted. 47%, 45% and 8% of the admissions were from 0-14, 15-64 and >=65 year olds, respectively. The daily NO2, SO2, PM2.5 and PM10 levels were 12.4, 8.5, 32.3 and 68.6 μm/m3, respectively. Daily air pollutant levels regularly exceeded the WHO guidelines. On cold days there were no significant associations between the air pollutants and RD admissions, but there were strong associations on warm days, except for NO2. On warm days, 0-14 year olds and females were more susceptible to PM2.5, PM10 and SO2, e.g. RR 1.12 95%CI 1.02-1.23 for 14 year olds and PM2.5 compared to the unstratified analyses RR 1.01 95%CI 1.00-1.02. Conclusions: These results indicate that the risk of RD hospital admission due to ambient air pollution exposure is different on cold and warm days in Secunda.