Mumbai’s PM10 levels highest among 3 major coastal cities in India: Study
80% increase recorded over 12 years; dust, industrial, vehicle emissions contribute most
With an 80% increase in the concentration of annual average particulate matter (PM) 10 - solid and liquid particles 10 microns or smaller, suspended in the air – witnessed over a 12-year period (2007-2018), Mumbai is the most polluted of the country’s three major coastal cities.
A compilation of Central Pollution Control Board (CPCB) data by the Centre for Science and Environment (CSE), Delhi, was presented during an air quality conference ‘Clearing the Air on Air Pollution’ on Friday. The data showed that PM10 levels over 12 years were above the safe limit of 60 micrograms per cubic metre (µg/m3) every year. A drastic rise from 92µg/m3 in 2007 to 166µg/m3 in 2018 resulted in an 80.4% increase in concentration indicating a steady year-on-year decline. PM10 levels were the highest over the last three years.
While most cities witnessed mixed trends, particulate pollution rise was highest in Mumbai as compared to any other coastal city. The three-year average PM10 concentration for Mumbai stood at 149µg/m3 as compared to 126µg/m3 for Kolkata and 65µg/m3 for Chennai. The average PM10 level for warm and humid climatic zones in the country is 110µg/m3.
“The trend indicates that motorisation and development pressures in the city are leading to this increase, despite having the advantage of sea breeze. We need to take note of this by manoeuvring and designing a clean air action plan for effective reduction,” said Anumita Roy Chowdhury, executive director (research and advocacy), CSE.
SN Tripathi, professor, Indian Institute of Technology-Kanpur and member of the National Clean Air Programme (NCAP) apex committee, said, “Official data collated by CSE is extremely alarming for a city like Mumbai and of concern as national safe standards are being exceeded continuously. With the NCAP action plan underway, there is a need to conduct measurement-based source apportionment studies at least once in two years if not every year to track and address emission changes on priority.”
CSE also analysed winter 24-hour PM2.5 (fine toxic particles that stay in the air longer and can easily enter the respiratory system) concentration between October 2018 and February 2019 and found that levels in November were the highest (2.1 times the safe standard). Overall, there were 33% moderately-polluted days; 5% poor air quality days, and 1% very poor air pollution day. From November to February, PM2.5 concentration was above safe standards on most days.
Based on current emissions, a 60% reduction in emission sources is needed to meet the clean air standards as proposed under the NCAP action plan for various cities across India by the Centre. “While the NCAP target for the country is a reduction of 30%, when we translate it for individual cities, the target reduction is higher for each sector and in this case, it is 60% for Mumbai,” said Chowdhury. “To be able to achieve this, priority sectors will be transport, construction, waste burning and solid fuel usage.”
According to a source apportionment study for PM10 in Mumbai by researchers from UrbanEmissions.info, dust emissions account for 50% of all emissions. This is followed by 28% industrial emissions; 11% from the transport sector, and 3% each from waste burning, diesel generator sets, and brick kilns. Residential emissions account for 2%. “While information generation is one side of the story, we need the engagement of researchers, official bodies and society to realise the benefits of policies for clean air in Mumbai,” said Sarath Guttikunda, lead author, founder and director, Urbanemissions.info.
Doctors said all age groups had witnessed a surge in health ailments, with elderly citizens and children more prone to the impacts of air pollution. “PM2.5 and PM10 are gradually rising in Mumbai every year, with atmospheric pollutants increasing the potency of allergens,” said Dr Swapnil Mehta, consultant (pulmonology), Dr L H Hiranandani Hospital.
On June 5, the Maharashtra Pollution Control Board (MPCB) said there had been a 6% decline in PM2.5 levels and 9% decline in PM10 levels across major cities in Maharashtra, including Mumbai, but could not support the claim with data.
“With an aim to reduce particulate pollution by 30% by 2025, we have begun work with all stakeholders across all 17 cities in Maharashtra including Mumbai. The state is extremely serious about the implementation,” said VM Motghare, joint director (air pollution), MPCB. “Reduction in private vehicles, boosting public transport network and recycling construction and demolition waste at source will be the focus points of the action plan.”
Mumbai has 19 air quality manual monitoring stations and 11 continuous monitoring (real-time) stations but researchers have highlighted that the city needs a total of 68 stations (another 38) to map detailed pollutant concentrations. Meanwhile, air quality monitoring stations that belong to the Brihanmumbai Municipal Corporation (BMC) have been dysfunctional for the past three years.
“Dust emissions over Mumbai are a matter of concern. We are working with MPCB on its action plan and addressing source-wise issues,” said Praveen Pardeshi, BMC commissioner. “As of now, expanding the city’s public transport system and discouraging private vehicles by modelling the Brihanmumbai Electric Supply and Transport (BEST) services through increasing fleet size and ridership is the focus to improve air quality alongside tackling construction and demolition waste at source,” he added.
Apart from enhancing the public transport network, Sudhir Srivastava, chairman, MPCB, said the planned introduction of cleaner fuels, reducing resuspension of windblown dust from construction and demolition waste and paving of roads combined with an increase in the distribution of more LPG connections to slum areas were critical targets under NCAP for Mumbai. “As per directions by the Union environment ministry, we are pushing for the acquisition of street cleaning machines to address the issue of resuspension of dust,” he said. “We have identified the problem and there is a concentrated plan in place. Things are expected to fall in place and we should see significant improvement in Mumbai’s air quality as we go along,” he said.
