Maha saw least improvement in urban pollution between 2017-22

Maharashtra was the worst-performing state in improving urban air quality between 2017 and 2022, with a dip of 7.7% in PM2.5 levels, according to a report by Climate Trends. Despite slight improvements in 2019, pollution levels rose again in 2020 and 2022. By comparison, Uttar Pradesh was the best-performing state with a reduction of 37.8% and 38.1% in urban and rural PM2.5 levels, respectively. The report also highlighted the viability of using remote sensing data to monitor air pollution in India.

Mumbai: Maharashtra was the worst-performing state when it came to improvements in urban air quality between 2017 and 2022, according to a report.

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Maharashtra registered a dip of 7.7% in its urban PM2.5 levels, and a decrease of 8.2% in rural PM2.5 levels (behind only Gujarat), according to a report-- Status of Urban and Rural air quality exposure at nation scale -- released Wednesday by Climate Trends, a climate research and communications group.

PM2.5 refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 micrometers, which is about 3% the diameter of a human hair.

From an annual average 48.7ug/m3 (micrograms per cubic metre of air) in 2017, PM2.5 concentration in urban Maharashtra improved slightly, settling at 43.1ug/m3 in 2019, but rose once again from 2020 onward despite Covid-induced lockdowns, touching 44.9ug/m3 in 2022.

Rural pollution levels saw a similar trend in the state, from 49.1ug/m3 in 2017, settling at 39.7ug/m3 in 2019, before rising to 44.5ug/m3 in 2022. By comparison, Uttar Pradesh was the best-performing state, with a reduction of 37.8% and 38.1% in urban and rural PM 2.5 levels, respectively.

“Data shows that PM 2.5 across the rural and urban regions have plateaued over the last six years and is witnessing a consistent decline,” the report notes, based on an analysis of remote sensing data, of 1km x 1km resolution, available with IIT-Delhi via the Centre’s Satellite-Based Application For Air Quality Monitoring and Management at National Scale (SAANS).

To be sure, though, data produced by this initiative is yet to be accepted by the Union environment ministry, per a disclaimer on the SAANS website.

Aarti Khosla, director, Climate Trends, said, “The analysis reflects the progress being made under the National Clean Air Programme with most states and union territories seeing a dip in their PM 2.5 levels over the last few years... However, western states like Maharashtra and Gujarat have made little progress and have seen the air pollution problem become significant in recent years. The first NCAP deadline of 2024 is close and action must move beyond cities in the programme’s next phase.”

The study also shows the viability of using remote sensing data to monitor air pollution in India, using a method called ‘Aerosol Optical Depth’, where ground-level monitors are inadequate in number.

“Annual averages, as derived from the SAANS satellite data and the CPCB’s ground monitoring network, do not differ significantly in most cases. It also shows that as processes to derive satellite-based PM 2.5 levels matured, the difference between the two data sets has narrowed down,” the report says.

SN Tripathi, steering committee member (NCAP), said about the analysis, “Overall PM2.5 trends based on this analysis show state-level reductions ranging from approximately 7-38%. Improvements with levels above 10% across this timescale should be considered positive. However, anything less than 10% needs to be evaluated.”