EXPOSURE ASSESSMENT IN THE DURBAN HEALTH STUDY - CONVENTIONAL POLLUTANTS

Abstract

ISEE-343 Introduction: This study describes the collection and analysis of conventional air pollutants as part of the health risk assessment / epidemiological study aimed at characterizing health impacts in the South Durban Industrial Basin. The primary focus is on particulate matter (PM10), sulphur dioxide (SO2) and carbon monoxide (CO) as priority pollutants. Methods: PM, SO2 and CO are being measured in seven community sites across Durban: four in the South, (Wentworth, Bluff, Merebank and Lamontville) and three in the north (Kwamashu, Newlands East and West). The south sites are located in an industrial basin near two petroleum refineries and a paper mill, while the north comparison sites are ∼25 km NW from major industry in the Basin. 24-hr PM samples were collected every day during four, three-week intensive phases (which coincided with bihourly lung function assessments of grade 4 pupils) and thereafter every 6th day using high, medium and low volume samplers. SO2 is monitored every 10 min with active continuous analysers (European monitor labs and API) according to internationally accepted methods. Monthly span and zero checks are performed on the analysers which are subjected to quarterly calibrations. CO is monitored every 5 min with passive continuous electronic analysers (HOBO) and subjected to span and zero checks twice a year. Data is downloaded from SO2 and CO analysers from all sites with a laptop twice a month. Results.: During the first intensive phase 24-hr PM10 levels in the north ranged from 20 to 267 μg/m3, while the south PM10 ranged from 28 to 156 μg/m3. In the second intensive phase, PM10 levels in the north ranged from 2 to 73 μg/m3 and the south ranged from 1 to 79 μg/m3. During the non-intensive phase PM in the north ranged from 8 to 179 μg/m3, while the south ranged from 2 to 208 μg/m3. Preliminary evaluation of SO2, reveals higher concentrations in the southern communities, namely Nizam and Assegai, with all sites displaying diurnal trends in pollution dispersion over a 24-hr period. A comparison of CO levels reveals that in May 2004, CO concentrations in Kwamashu and Newlands were nearly double those at other sites. Discussion/Conclusion.: The monitored data may be compared to South Africa's air pollution guidelines, specifically, the 24-hr PM10 guideline of 75 μg/m3, is discussed. Overall, PM levels decreased over the second intensive phase, however, monitored levels of PM10 in north and south Durban often exceeded the 24-hr guideline. Some variation was noted between north and south for the different pollutants, e.g., PM levels were higher in the north, while SO2 levels were higher in the south. This is probably due to the impact of industrial activity in the south, compared to open fields and biomass fuel burning in the north. These findings allow for the investigation of health effects in these different communities.