Poonam Mangaraj1,3, Saroj Kumar Sahu  This email address is being protected from spambots. You need JavaScript enabled to view it.2, Gufran Beig3, Ashirbad Mishra2, Som Sharma4

1 Research Institute for Humanity and Nature, Kyoto, Japan
2 Department of Environmental Science, Berhampur University, Berhampur, India
3 National Institute of Advanced Studies, IISc-Campus, Bangalore, India
4 Physical Research Laboratory, Ahmedabad, India

Received: March 30, 2024
Revised: June 27, 2024
Accepted: June 27, 2024

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.240089  

Cite this article:

Mangaraj, P., Sahu, S.K., Beig, G., Mishra, A., Sharma, S. (2024). What Makes the Indian Megacity Chennai’s Air Unhealthy? - A Bottom-up Approach to Understand the Sources of Air Pollutants. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.240089


  • Region and source-specific emission hotspots of Chennai are identified.
  • Road dust (28%) contributes maximum to total PM10.
  • Vehicular (23%) and industrial (20%) sector remain the major contributors to PM10.
  • Rising open burning of MSW (13%) needs alternative approaches.


In recent years, air quality in Indian megacities has emerged as the most pressing global concern, with Asian megacities being the most polluted. Unlike India's pollution capital, Delhi, Chennai is a megacity with a significant impact on industrial and transportation activities and has been designated as a non-attainment city by the Government of India under the National Clean Air Programme. The first step towards sustained clean air is identifying the sources that are causing the megacity's air quality to deteriorate. The current study is the first-ever attempt to develop bottom-up inventory at ultra-fine resolution (i.e., ~0.4 km × ~0.4 km) where, the annual emission includes 39.6 Gg yr-1 of PM2.5, 65.0 Gg yr-1 of PM10, 387.3 Gg yr-1 of CO, 175.2 Gg yr-1 of NOx, 70.9 Gg yr-1 of SO2, 271.4 Gg yr-1 of VOC, 10.5 Gg yr-1 of BC, and 17.7 Gg yr-1 of OC for the base year 2020. This cutting-edge data on surface emissions with identified hotspots, would be vital tool for air quality studies as well as the first step towards framing mitigation strategies for sustainable air in Chennai.

Keywords: Anthropogenic sources, Emission inventory, Urban air quality, Megacity, Clean air, Mitigation strategies

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