Heavy dust and particulate matter (PM) in the air is a result of not only a surge in vehicular emissions and construction within the city, but also a cocktail of emissions from thermal, metal, wire industries, stone quarries, movement of freight trucks and garbage burning across 12 locations in the Mumbai Metropolitan Region (MMR).
A first-of-its-kind satellite study of the city by air pollution research group UrbanEmissions.info identified that activities and their scale of operations across these 12 areas had a direct impact on rising PM2.5 – fine toxic particles that stay in the air longer and cause serious respiratory ailments.
These locations have been identified as Jasai freight hub in Uran; Wadala truck terminal; Victoria Docks in Mazgaon; clamp-style brick kilns near Tembavali village, Bhiwandi; power plants and industries in Trombay; textile units near Kaire village in Raigad district; metal processing units at Waliv town in Thane district; paper and textile units at Maharashtra Industrial Development Corporation (MIDC) area along the Ulhas river at Bhiwandi; industrial setup in Winjale village, Thane; wire mills in Indal Colony in Kalwa, and garbage burning at the Deonar dumping ground. Most of these locations are spread across an average of one to 6 sq km. The study was released as a part of the Air Pollution Knowledge Assessment (APnA) city program for 50 cities during an air quality conference organised in Mumbai on Friday.
“It is important to acknowledge that there are emission sources affecting local air quality that we do not see on a daily basis,” said Sarath Guttikunda, lead author, founder and director, Urbanemissions.info, citing examples such as power plants that electrify homes, petroleum refineries, and brick kilns. “For clean air, we need to address all the sources that are present within the city’s air-shed. While the industrial hubs are outside the city limits, the dispersion of these emissions affects Mumbai’s air directly,” he added.
Based on satellite data, the study mapped the spatial extent of each location across an 80km x 80km domain further segregated into 1km grids. “This is a bottom-up exercise aimed at understanding the key sources of air pollution with as much granularity as possible. Depending on the type of industry and fuel burnt, we have a mix of pollutants including sulfur dioxide, nitrogen oxides, volatile organic compounds, and general dust,” said Guttikunda.
Maharashtra Pollution Control Board (MPCB) said the dispersion model for each of the 12 sources needed to be studied. “We may be witnessing sources outside Mumbai’s air-shed, but their contribution on the receptors’ end has to be seen,” said Sudhir Srivastava, chairman, MPCB. “The ambient air quality in some regions due to naturally-prevailing dust is so high that man-made contributions are low in comparison. These issues will be analysed in under the air pollution action plan.”
