Air pollution is a critical global threat, impacting millions worldwide. A groundbreaking study by researchers at the Indian Institute of Technology (IIT) Jodhpur, published in Nature Communications, offers crucial insights into the sources and composition of harmful particulate matter (PM) in Northern India.
This research challenges the common belief that simply reducing overall PM mass is enough. Dr. Deepika Bhattu, the study’s lead author and Associate Professor at IIT Jodhpur, emphasizes the importance of tackling local inefficient combustion processes. These include burning biomass and fossil fuels, alongside traffic exhaust. Effectively addressing these issues is key to reducing PM-related health risks in Northern India.
The study tackles three critical questions to guide policymakers in developing effective air pollution mitigation strategies under the National Clean Air Programme (NCAP):
- Identifying PM2.5 Sources and Contributions: The research pinpoints the exact sources of fine particulate matter (PM2.5), both local and regional, with unprecedented clarity.
- Directly Emitted vs. Atmospherically Formed PM: For the first time, the study offers a clear distinction between PM directly released into the air and PM formed through atmospheric processes, across a vast geographical area and time period.
- PM Harmfulness and Source Correlation: The research determines the harmfulness of PM by correlating its oxidative potential with local and regional sources within the study region.
Advanced techniques and data analysis were employed across five Indo-Gangetic Plain sites, both within and outside Delhi. The findings reveal:
- While PM concentrations remain high across the region, the chemical composition varies significantly. Local emission sources and formation processes heavily influence PM pollution.
- In Delhi, ammonium chloride and organic aerosols dominate PM pollution. These originate from traffic exhaust, residential heating, and the atmospheric oxidation of fossil fuel emissions.
- Outside Delhi, ammonium sulfate, ammonium nitrate, and secondary organic aerosols formed from burning biomass are the major contributors.
Regardless of location, the study highlights a crucial point: Organic aerosols produced during the incomplete combustion of biomass and fossil fuels, including vehicle emissions, are the primary contributors to PM’s oxidative potential. This potential is directly linked to the health impacts of PM in the region.
The study’s findings regarding PM oxidative potential are particularly alarming. Compared to PM2.5 in Chinese and European cities, PM in India exhibits an oxidative potential up to five times higher. This marks it as some of the most harmful PM observed globally.
Dr. Bhattu emphasizes that addressing India’s air pollution crisis necessitates collaboration among various stakeholders, including local communities. Societal changes are especially crucial in densely populated urban areas like Delhi.
Moving forward, concerted efforts are required to promote cleaner energy sources, improve combustion efficiency, and reduce transportation emissions. This includes tackling outdated, overloaded vehicles, and removing unauthorized “jugaad” vehicles.
This research offers valuable insights for crafting evidence-based policies and interventions. By prioritizing mitigation strategies that target the most significant health impacts, particularly those arising from local inefficient combustion processes, substantial progress can be made in safeguarding public health and the environment for future generations in Northern India.