Poor urban planning made Mumbai’s air worse: Study
The massive infrastructural transformation of the city, from a 384-square kilometre (sq.km) built-up area in 1975 to 885 sq.km in 2014, has been one of the primary drivers of the spiralling air pollution in the financial capital, revealed a study by air pollution research group, Urbanemissions.info.
While there has been a 130% rise in built-up area or urbanised spaces over 39 years, particulate matter or PM2.5 concentration in the air rose to 51.8μg/m3 in 2018, from 36.9μg/m3 in 1998 (earliest available data with Urbanemissions.info).
According to the Surveyor General of India, the Greater Mumbai Municipal Corporation currently covers an area of 603sq.km —13.8% of 4,355 sq.km, the area of the Mumbai Metropolitan Region (MMR). Of this, approximately 2,000km is the total length of major roads.
The study by Urbanemissions.info mapped the spatial footprint of Mumbai across 1975, 1990, 2000 and 2014. The group selected an 80km x 80km domain area and further divided it into 1-km grids to study the land-use variations over the years and compared it to the corresponding emission and pollution loads.
Based on these comparisons, the study predicted that PM2.5 emissions in the city will rise 23% — to 60,950 tonnes in 2030 from 49,600 tonnes in 2018.
“This information [from 1975 to 2014] is a direct indicator of the urban growth — a proxy for housing, road construction, commercial expansion, and overall energy demand — leading to rise in air pollution. We can see the growth trends and anticipate urban growth in the airshed for the next 10 and 20 years,” said Sarath Guttikunda, leader author, founder and director, Urbanemissions.info.
Guttikunda said Mumbai has seen a lot of vertical development in the past two decades as compared to cities like Hyderabad, which have witnessed both vertical and horizontal development. “We can use such comparisons for one-on-one correlation with urban air quality,” he said.
The state urban development department (UDD), however, estimated that from 2014 to 2019, the built-up area would have increased in the same manner as “witnessed gradually” from 1975 to 2014.
“The last five years may have not seen a huge spurt in development,” said Nitin Kareer, principal secretary, UDD. “Mumbai already has a very high percentage of people using public transport as compared to any other city in India. Though 80% of commuting is done using public transport, moderately high pollution levels are witnessed. Though levels are not as high as other cities, Mumbai has the advantage of sea-breeze.”
Moreover, according to a chart, depicting average speed of daily traffic for every hour of a week and the corresponding pollution levels, released by the group, staggered vehicular movement in rush hours increases air pollution. Compared to the other cities, the average speed in urban Mumbai during the rush hour is lowest (around 12 km/h), said Guttikunda.
“The comparison indicates vehicular emissions during rush hours. Staggered movement in the morning, followed by day-time movement, evening rush hour when everyone is trying to get home at the same time, and finally, the night-time freight movement all account for more than 9,000 tonnes of PM2.5 emissions annually,” he said, adding, “Though Mumbai has an extensive public transportation network, such a drastic increase in built-up area and accompanying population shows the city needs to invest much more and expand public transport options.” The study also noted that: “Speeds are greater at night and on Sundays and slows at peak hours during the week, establishing hourly time frames for high pollution levels,” the study said.
Kareer also said the state is focusing on expanding public transport and reducing pollution levels. He said Maharashtra is the only state which allots 50% of funds to support the suburban rail transport network and sanctions large amount of money for Mumbai Urban Transport Project (MUTP) I, II and III.
“The approved Metro lines are currently under construction. In the next five years, the Metro network will be larger than the suburban railway network. Thirdly, initiatives by the Brihanmumbai Electric Supply and Transport (BEST) network, in terms of increasing ridership and the fleet size, and inducting electric buses will also help. With these three projects in place, the focus of the state is on public transport, improving mobility, and thereby reducing air pollution,” he said.