Biomass burning, including the combustion of wood, charcoal, and agricultural residues, is a major source of PM2.5, a fine particulate matter that degrades air quality and poses risks to human health. Much of this pollution is tracked by looking at levels of levoglucosan, a chemical that is formed when cellulose in plants is burned, from biomass combustion such as residential fuel use, cooking, and open burning.
However, what if atmospheric loss of levoglucosan is not properly accounted for?
That is the question posed in a new study by Osaka Metropolitan University (OMU), which found that levoglucosan was heavily degraded chemically after being emitted into the air.
“We estimate that about 88% of it was lost due to atmospheric degradation and volatilization,” Associate Professor Yusuke Fujii of the Graduate School of Sustainable System Sciences at OMU said. “Conventional analyses that do not account for this loss risk misidentifying emission sources.”
This is especially true in tropical areas as sunlight speeds up degradation of the chemical. This raises concerns that previous research that is based on levoglucosan remaining stable without deteriorating is not telling the whole story. If pollution sources are misidentified, it could result in less effective allocation of financial resources.
This was supported by the findings of the study. In Ho Chi Minh City, Vietnam, they found that without correcting for the chemical degradation, the pollution appeared to come mainly from crop residue and grass burning, common rural practices in Southeast Asia.
But, after correcting for the lost levoglucosan, the data instead pointed to hardwood and charcoal burning, especially cooking-related emissions, in urban areas of Ho Chi Minh City.
“In Vietnam, urban air pollution remains a serious concern,” Ngoc Tran, a Vietnamese researcher from OMU’s Graduate School of Sustainable System Sciences, said. “There is a strong need to clarify the detailed contributions of these sources, specifically what is being burned and where, in order to develop effective mitigation strategies.”
“By optimally integrating established methods with local environmental conditions, it is possible to more accurately evaluate the types and relative contributions of biomass burning that were previously difficult to distinguish. This approach will contribute to improving the accuracy of source apportionment in urban areas worldwide,” Fujii adds.
The findings were published in ACS Omega.
Conflict of interests
The authors declare no competing financial interest.
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