Air pollution trend in Chandigarh city situated in Indo-Gangetic Plains: Understanding seasonality and impact of mitigation strategies

Khaiwal Ravindra; Tanbir Singh; Vivek Pandey; Suman Mor

doi:10.1016/j.scitotenv.2020.138717

Air pollution trend in Chandigarh city situated in Indo-Gangetic Plains: Understanding seasonality and impact of mitigation strategies

Sci Total Environ. 2020 Aug 10:729:138717. doi: 10.1016/j.scitotenv.2020.138717. Epub 2020 Apr 17.

Authors

Khaiwal Ravindra¹, Tanbir Singh², Vivek Pandey³, Suman Mor²

Affiliations

¹ Department of Community Medicine and School of Public Health, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh 160012, India. Electronic address: khaiwal@yahoo.com.
² Department of Environment Studies, Panjab University, Chandigarh 160014, India.
³ Chandigarh Pollution Control Committee, Chandigarh 160019, India.

PMID: 32498156
DOI: 10.1016/j.scitotenv.2020.138717

Abstract

The long-term trend of air pollutants was studied in Chandigarh, located in Indo-Gangetic Plains of India. The SPM, PM₁₀, NO_x, and SO₂ depict site-specific variation having different anthropogenic activities. The results indicate that PM₁₀ levels in Chandigarh remain higher than the prescribed annual ambient air quality standards (60 μg m^-3) of India. Seasonal Kendall test indicates a declining trend of PM₁₀ for the year 2003 to 2018 at an industrial and commercial site (1996-2016). There is a significant increase in NOx levels at all locations except at commercial sites. The results of the linear regression model and Theil-Sen slope show that SPM is declining at all locations, but results are not statistically significant. Interestingly, PM₁₀ levels at the industrial site display a significant declining trend (1.3% year^-1). Similarly, NOx levels are increasing at all sites but having a statistically significant trend at a rural location (8.9% year^-1) and residential site (15.2% year^-1). Air pollutants show strong seasonal variability having a higher concentration in post-monsoon and winter season, which found to be linked with regional anthropogenic activities such as crop residue burning and use of solid biomass fuel for cooking and other purposes. Lowest PM₁₀ levels were observed during the monsoon and having a decline of 47.4-66.4% as compared to winter levels. Site-specific variations in air pollutants were found to be associated with air quality improvement policies such as shifting of an interstate bus terminal, ban on diesel autos, including strict implementation of air quality norms on industries. As the relative contribution of various pollution sources is still unknown, the seasonal pattern of pollutants will help in knowing the background concentration of pollutants and could help to formulate evidence-based policies to mitigate air pollution under National Clean Air Programme (NCAP).

Keywords: Air pollution trend; Indo-Gangetic Plains; NCAP; Non-attainment cities; Planned cities; Policy implication.