Respirable particulate matter concentration at a waste disposal site in the Gauteng Province, South Africa

Abstract

Background Particulate matter from landfill sites poses significant public health risks, contributing to various respiratory and cardiovascular health effects. In South Africa, urbanisation has led to increased proximity of residential areas to landfill sites, exacerbating exposure to airborne respirable dust. Purpose This study aimed to determine the differences in respirable dust concentrations at the centre of the landfill and at the perimeter and determine factors that affect respirable dust concentrations in landfills. Methods A quantitative cross-sectional study was conducted at the Palm Springs landfill site in Evaton, Gauteng Province, during May and June 2023. Gravimetric sampling was used to collect 40 respirable dust samples over five days from eight locations allowing comparison between the landfill source and its perimeter. Concurrent meteorological data, including temperature, relative humidity, and wind speed, and distance from the source were recorded. Data were analysed using the Kruskal–Wallis test and Student t-test to compare dust concentrations while simple linear regression analysis assessed relationships between dust levels and influencing variables. The ExpoStats Bayesian Toolkit was also applied to enhance comparison and interpretation across sampling locations. Results Respirable dust concentrations were consistently higher at the landfill source, particularly in the southeastern section where waste sorting and handling activities were most intensive. Concentrations reached 1.64 mg/m³ at the source and 1.02 mg/m³ at the 250-meter perimeter. Regression analysis indicated no statistically significant associations between dust levels and v temperature, wind speed, or distance, suggesting that these factors may exert indirect or site- specific influences. In contrast, relative humidity showed a significant relationship (p < 0.034), highlighting its role as a key determinant of dust behavior. The model’s predictive accuracy, however, was limited, with an average error of approximately 40%, reflecting the complex environmental interactions affecting dust suppression. Conclusion Respirable dust concentrations were consistently higher at the landfill source than at the perimeter. The findings confirm the landfill as a significant emission source of respirable dust. However, meteorological parameters and distance demonstrated weak predictive power, as reflected by low R² values, indicating that these factors alone do not sufficiently account for dust variability. This suggests that dust dispersion is influenced by more complex interactions, particularly operational practices and site-specific environmental conditions. These insights underscore the importance of developing more comprehensive predictive models and implementing targeted air quality management policies to mitigate dust exposure risks around landfill sites.