18-Year Ambient PM2.5 Exposure and Night Light Trends in Indian Cities: Vulnerability Assessment

Received: November 16, 2017
Revised: January 25, 2018
Accepted: January 26, 2018
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2017.10.0425  

Cite this article:
Pal, R., Chowdhury, S., Dey, S. and Sharma, A.R. (2018). 18-Year Ambient PM2.5 Exposure and Night Light Trends in Indian Cities: Vulnerability Assessment. Aerosol Air Qual. Res. 18: 2332-2342. https://doi.org/10.4209/aaqr.2017.10.0425

HIGHLIGHTS

• 18-year (1998–2015) statistics of ambient PM_2.5 exposure in 100+ cities of India.
• Annual PM_2.5 exposure increased by 63.0 ± 8.6% in the last two decades.
• Night light data are used as proxy to urbanization rate.
• 51 out of the 60 cities under 'smart city' mission are vulnerable to air pollution.

ABSTRACT

Exposure to ambient fine particulate matter (PM_2.5) is identified as one of the leading risk factors for morbidity and mortality in India. Here we estimate ambient PM_2.5 exposure and its 18-year (1998–2015) trend in 109 Indian cities using satellite data and further classify them into six vulnerable classes (from index 1 for low vulnerability to index 6 for extreme vulnerability). PM_2.5 exposure has shown a rapid increase in Delhi and the cities in Uttar Pradesh, Bihar, Jharkhand, West Bengal, Punjab, Haryana, Rajasthan, Madhya Pradesh, Chhattisgarh and Odisha. Amongst the cities with a population of more than 0.5 million (as per the 2011 census), Thiruvananthapuram is the least vulnerable and Aligarh is the most vulnerable city based on 18-year statistics. Only 27 cities are identified as ‘low’ to ‘moderately’ vulnerable to ambient air pollution. The median incremental rate of the annual PM_2.5 exposure has increased by 57.9% (from 0.9 to 1.15 µg m^–3 per year) with the night-light counts (a proxy for urbanization rate) increasing from < 20^th percentile to > 80^th percentile. 51 out of the 60 Indian cities chosen for the ‘smart city’ mission are highly vulnerable to PM_2.5 exposure (vulnerability index > 2) and thereby face challenges to achieve the core objective of the mission (i.e., a sustainable environment). Our results will facilitate prioritizing a clean-air action plan for the cities based on their vulnerability rankings to achieve the maximum health benefit for the exposed population.

Keywords: PM2.5; Remote sensing; Indian city; Night light; Health-risk; Vulnerability.