News Excerpt:
The research conducted by the Indian Institute of Technology (IIT) Jodhpur, as published in the Nature Communications journal, sheds crucial light on the sources and composition of particulate matter (PM) in northern India, a region grappling with severe air pollution issues.
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Particulate Matter:
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More About the News:
- The study challenges the conventional notion that reducing overall PM mass alone would mitigate health impacts.
- Instead, it emphasises the urgent need to address local inefficient combustion processes, such as biomass and fossil fuel burning, along with traffic exhaust, to effectively reduce PM-related health risks.
Key Findings of the Study:
Importance of Local Combustion Processes: Contrary to the common belief that reducing overall PM mass would alleviate health impacts, this comprehensive study emphasizes the importance of addressing local inefficient combustion processes—such as biomass and fossil fuel burning, including traffic exhaust to effectively reduce PM-related health exposure and associated impacts in northern India.
Critical Scientific Questions Addressed: The study addresses three critical scientific questions essential for Indian policymakers as they devise data-driven, effective mitigation strategies under the National Clean Air Programme (NCAP):
- Fine PM (PM2.5) Source Identification: The research offers unprecedented clarity in identifying the sources of fine particulate matter (PM2.5) and their absolute contributions. It distinguishes between local and regional geographical origins, providing a detailed understanding of pollution sources.
- The distinction between Directly Emitted and Atmospherically Formed PM: For the first time on a large spatial and temporal scale, the study makes a clear distinction between PM directly emitted from sources and those formed in the atmosphere. This distinction is crucial for developing accurate pollution control measures.
- Correlation of PM Harmfulness with Sources: The study correlates the oxidative potential of PM with local and regional sources within the study region. The oxidative potential, a measure of the harmfulness of PM to human health, highlights the significant health impacts of organic aerosols from incomplete combustion of biomass and fossil fuels, including traffic emissions.
Methodology & Findings:
- Using advanced aerosol mass spectrometry techniques and data analytics, the study was conducted at five Indo-Gangetic plain sites, both within and outside Delhi.
- It found uniformly high PM concentrations across the region but with considerable variability in chemical composition dominated by local emission sources and formation processes.
- Within Delhi: Ammonium chloride and organic aerosols from traffic exhaust, residential heating, and oxidation products of fossil fuel emissions dominate PM pollution.
- Outside Delhi: Ammonium sulphate, ammonium nitrate, and secondary organic aerosols from biomass burning vapours are the dominant contributors.
- Regardless of location, the study highlighted that organic aerosols from incomplete combustion of biomass and fossil fuels, including traffic emissions, are key contributors to the PM oxidative potential, driving PM-associated health effects in the region.
Global Context and Policy Implications:
- The oxidative potential of Indian PM2.5 surpasses that of Chinese and European cities by up to fivefold, marking it as one of the highest observed globally.
- This alarming finding underscores the urgent need for effective mitigation strategies.
Conclusion:
The study provides valuable insights for evidence-based policies and interventions to safeguard public health and the environment for future generations. Prioritising mitigation strategies based on the most significant health impacts, particularly targeting local inefficient combustion processes, is essential in Northern India.
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The National Clean Air Programme (NCAP)
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