Characterization of fine particulate matter from indoor cooking with solid biomass fuels

Abstract

Household burning of solid biomass fuels emits pollution particles that are a huge health risk factor, especially in low-income countries (LICs) such as those in Sub-Saharan Africa. In epidemiological studies, indoor exposure is often more challenging to assess than outdoor exposure. Laboratory studies of solid biomass fuels, performed under real-life conditions, are an important path toward improved exposure assessments. Using on-and offline measurement techniques, particulate matter (PM) from the most commonly used solid biomass fuels (charcoal, wood, dung, and crops residue) was characterized in laboratory settings using a way of burning the fuels and an air exchange rate that is representative of real-world settings in low-income countries.All the fuels generated emissions that resulted in concentrations which by far exceed both the annual and the 24-hour-average WHO guidelines for healthy air. Fuels with lower energy density, such as dung, emitted orders of magnitude more than, for example, charcoal. The vast majority of the emitted particles were smaller than 300 nm, indicating high deposition in the alveoli tract. The chemical composition of the indoor pollution changes over time, with organic particle emissions often peaking early in the stove operation. The chemical composition of the emitted PM is different for different biomass fuels, which is important to consider both in toxicological studies and in source apportionment efforts. For example, dung and wood yield higher organic aerosol emissions, and for dung, nitrogen content in the organic PM fraction is higher than for the other fuels. We show that aerosol mass spectrometry can be used to differentiate stove-related emissions from fuel, accelerant, and incense. We argue that further emission studies, targeting, for example, vehicles relevant for LICs and trash burning, coupled with field observations of chemical composition, would advance our understanding of air pollution in LIC. We believe this to be a necessary step for improved air quality policy. K E Y W O R D Scharcoal, indoor exposure, PM 2.5 , Sub-Saharan Africa, woodThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Toxicity of particles derived from combustion of Ethiopian traditional biomass fuels in human bronchial and macrophage-like cells

“…Size distribution and particle composition of the airborne particles, as well as emission factors and exposure levels were previously reported by Eriksson et al ( 2022 ).…”

“…As previously described in Eriksson et al ( 2022 ), the PM 2.5 mass concentration levels varied greatly depending on the biomass source demonstrating concentrations levels generated from wood to be more than one order of magnitude higher than from charcoal, with the levels generated by dung being yet another order of magnitude higher. The difference in acute toxic responses between dung, eucalyptus wood and charcoal exposure presented in this study may therefore be considered even greater when accounting for the difference in exposure levels.…”

“…The high emission generation rate coupled with the heightened toxic potency of biomass particles derived from dung compared to cleaner alternatives such as charcoal (and our reference DEP), points towards the most resource constrained households being at greatest risk. Nonetheless, the exposure, based on 4 h cooking, is expected to exceed both the annual and 24-h average of the WHO guidelines for healthy air for all three solid biomass fuels investigated in this study (Eriksson et al 2022 ). Encouraging the adoption of cleaner fuel alternatives is crucial in reducing hazardous exposures in households across sub-Saharan Africa and in this context, studies like this one can provide insight and input.…”

“…Biomass fuels including charcoal made from eucalyptus, wood of eucalyptus and dried cow dung were brought from central Ethiopia to Lund University, Sweden and used without modification. Combustion particles from solid fuels were generated as previously described in Eriksson et al ( 2022 ). Briefly, the combustion of solid fuels was performed in a laboratory setup but under conditions and with procedures representative for real-world settings in low-income countries.…”

Enhancing soot oxidation using microtextured surfaces

“…The combustion of biomass typically emits significant amounts of carbonaceous particulate matter (PM; also referred to as soot) 5 . This biomass generated PM is one of the main contributors to indoor pollution 6 , 7 and outdoor air pollution 8 , 9 that leads to 8 million excess deaths per year 10 . Soot also contributes to climate change by changing cloud formation 11 and absorbing solar radiation 12 .…”