Elevated Black Carbon Exposure Among Individuals Burning Waste

SALONI VIJAY, Lennox Khonje, Mwaiwathu Laurent Chatha, Elizabeth Tilley, ETH Zürich

     Abstract Number: 150
     Working Group: Aerosol Exposure

Abstract
Globally, about 14% of households have no option but to burn their waste. While open waste burning is a significant source of black carbon (BC) emissions, personal exposure among those involved remains poorly understood. This study presents the first direct assessment of BC exposure from open waste burning. Between November and December 2023, we monitored 46 individuals from 23 households in Blantyre, Malawi, for approximately 20 hours on days when waste was burned. In each household, one waste burner and one non-burner wore MicroAeth MA200 monitors to track personal BC exposure. We calculated average BC concentrations for each participant during the full monitoring period, during burning, and during non-burning times. The median of these averages was then used to characterize exposure levels. We also characterized the waste being burned and recorded stirring frequency to assess their influence on exposure. The median exposure during burning was 12.8 μg/m³ for burners—over four times higher than the 2.9 μg/m³ for non-burners. During the full monitoring period, the median exposure for burners was 5.1 μg/m³, statistically higher than 3.0 μg/m³ for non-burners (Wilcoxon signed-rank test, p = 0.04). During non-burning times, there was no significant difference between the two groups (p = 0.44). The total exposure of burners during burning increased with the amount of waste burned and how often it was stirred. However, the mean concentrations of BC exposure during burning did not increase with waste quantity, suggesting behavioral adjustments to avoid smoke inhalation. While stirring improves combustion and lowers emissions, our findings show it also increases personal exposure. Overall, the study highlights the high black carbon exposure among waste burners and the associated health risks.