Air pollution trends over Indian megacities and their local-to-global implications

B. R. Gurjar, Khaiwal Ravindra, Ajay S Nagpure

Research output: Contribution to journalReview articlepeer-review

200 Scopus citations


More than half of the world's population lives in urban areas. It is estimated that by 2030 there will be 41 megacities and most of them will be located in developing countries. The megacities in India (Delhi, Mumbai, and Kolkata) collectively have >46 million inhabitants. Increasing population and prosperity results in rapid growth of the already large consumption of energy and other resources, which contributes to air pollution, among other problems. Megacity pollution outflow plumes contain high levels of criteria pollutants (e.g. Particulate matter, SO2, NOx), greenhouse gases, ozone precursors and aerosols; which can affect the atmosphere not only on a local scale but also on regional and global scales. In the current study, emissions and concentration trends of criteria and other air pollutants (polycyclic aromatic hydrocarbons, carbon monoxide and greenhouse gases) were examined in the three Indian megacities. Further, various policies and control strategies adopted by Indian Government are also discussed to improve air quality. Decreasing trends of SO2 was observed in all three megacities due to decrease in the sulfur content in coal and diesel. However, increasing trend for NOx was found in these megacities due to increase in number of vehicles registered and high flash point of CNG engines, which leads to higher NOx emission. In terms of SPM and PM10, highest emissions have been found at Kolkata, whereas highest ambient concentrations were recorded in Delhi. For Mumbai and Kolkata fluctuating trends of SPM concentrations were observed between 1991 and 1998 and stable afterwards till 2005; whereas for Delhi, fluctuating trend was observed for the entire study period. However, several steps have been taken to control air pollution in India but there is a need to focus on control of non-exhaust emissions including municipal solid waste and biomass burning in the megacities and surrounding areas.

Original languageEnglish (US)
Pages (from-to)475-495
Number of pages21
JournalAtmospheric Environment
StatePublished - Oct 1 2016

Bibliographical note

Funding Information:
RK also would like to thank Department of Health Research (DHR), Indian Council of Medical Research, Ministry of Health and Family Welfare, for providing the Fellowship Training Programme in Environmental Health under Human Resource Development Health Research Scheme. He would like to thank Natural Environment Research Council and the Medical Research Council from UK and the Earth System Science Organization, Ministry of Earth Sciences (ESSO-MoES) and Department for Biotechnology (DBT) from India for providing financial support for Delhi-AIRQUALNET project.

Publisher Copyright:
© 2016 Elsevier Ltd


  • Air quality management
  • Carbon dioxide
  • Methane
  • Odd-even scheme
  • PAHs


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