Experts Explain: How to fix Mumbai’s air | Explained News

Why has air pollution become a problem in Mumbai?

Mumbai is surrounded by the sea on three sides. Coastal cities see strong winds, which sweep away suspended pollutants in the air. Despite this geographical advantage, a combination of natural and man-made factors are driving down the city’s AQI.

• According to Prof Beig, due to a change in climatic conditions, the pattern of wind reversal (the alternating movement of winds from land to sea and sea to land, which takes place every 3-4 days at this time of year) is taking longer than usual, as a result of which winds have also become weaker.

After the southwest monsoon retreated on October 10, Mumbai has been experiencing relatively calm air, which has contributed to the delayed wind reversal.

• “Mumbai had an unusually hot October. A steep temperature gradient between the city and nearby hilly regions resulted in winds from these areas moving towards Mumbai, picking up dust from major construction projects in Navi Mumbai and surrounding areas,” Beig said.
• He flagged ongoing construction works as a major factor for the poor air. “The past three years have seen frenetic construction in Mumbai. These are resulting in a huge displacement of dust, and the prevalent climatic conditions are making dust particles linger in the lower atmosphere for longer,” Beig said.
• “Refineries, industries, and garbage-burning are adding to the problem,” he added.

Beig, however, said he believes the current problem is temporary. “So many construction works have been taken up in a short span of time, without adequate planning for dust mitigation measures. The AQI will get better once the projects are completed,” he said.

What steps can government and civic authorities take?

• It is important to first increase AQI monitoring in the city, Prof Tripathi said. Mumbai has 21 AQI monitoring stations, which is less than a third of the National Clean Air Programme’s (NCAP) recommended number.

“When you are trying to evaluate the air, you need to first identify the sources that contribute to the factors that determine the AQI. For example, if garbage burning is taking place somewhere in the eastern suburbs, it may impact only those who live close by,” Tripathi said.

All 21 monitoring stations in Mumbai use Continuous Ambient Air Quality Monitoring Systems (CAAQMS), which compute the air quality by trapping dust particles in
the inlet. Each station costs between Rs 1.3 crore and Rs 1.5 crore.

Authorities should also consider setting up sensor-based AQI monitoring units that give hyperlocal data, Tripathi said. Each of these units costs around Rs 50,000.

• According to Tripathi, it is also important to integrate the AQI monitoring system with the existing command and control system of the administration.

“This will not only give us the advantage of denser monitoring but will also empower the authorities to take immediate preemptive action, because you can take action only when you have adequate information.

“For example, if it is found that construction is taking place in a certain pocket without following norms, the authorities can identify the location and immediately penalise the violators,” Tripathi said.

• Also, according to Tripathi, Mumbai should adopt a commission for air quality management. In the same way as sources of pollution in Punjab, Haryana (such as stubble burning) and UP impact Delhi, the air in Mumbai is affected by activities that take place in Thane, Navi Mumbai, Bhiwandi, etc., he said.

“The wind does not obey jurisdictions but the bureaucracy has to, so the municipal commissioner of Mumbai would not be able to take action against garbage burning in Thane or Navi Mumbai, even if the pollution from the site affects Mumbai’s AQI,” Tripathi said.

“To address this issue, one needs to set up an independent commission for management of AQI. This commission should empower members to take action against any violator irrespective of geographical borders. This system has done fairly well in Delhi; the authorities have taken action in Haryana, UP, and Rajasthan for activities that would affect the city’s air.”

• It is also important that alongside upgrading the technical infrastructure, urban local bodies and pollution control boards have trained manpower available in the system.

“The administration needs to rope in an adequate number of engineers, scientists, health experts, and legal advisers. If you look at Delhi or London, so many solutions have been chalked out based on long term research carried out by scientists and experts. In Mumbai, academic institutions are hardly involved and I believe that including them in the search for solutions will bring better results,” Tripathi said.

• According to Beig, Mumbai also needs to carry out an emissions-based study to frame and implement policies relating to vehicular pollution.

“There are several bottlenecks in Mumbai that see huge traffic congestion. An emissions study needs to be done for these junctions and, based on the findings, an emissions-based policy needs to be chalked out and implemented immediately on the ground,” Beig said.

• Also, Beig underlined, monitoring and implementation are key. “Policies on paper are of no use unless they are implemented rigorously on the ground. The civic body and the state government need to ensure that all policies are followed,” he said.

How can citizens contribute to efforts to combat air pollution?

• The authorities must carry out widespread campaigns to raise awareness among the public on the need to cut vehicular emissions, Tripathi said. “Citizens can use bicycles and perhaps walk more, which can reduce overall tailpipe emissions to some extent,” he said.
• “The administration may also include citizen’s participation in their command-and-control system, so that they can complain by sending photographs whenever unauthorised construction or activities like garbage burning take place,” Tripathi added.
• The administration should also implement policies to encourage citizens to switch to piped natural gas from unclean combustion methods such as chullahs and stoves, he said.

What can Mumbai learn from the experience of other cities?

• Mumbai can learn the adaptability methodologies that cities like Delhi and London have embraced in the past few decades, Tripathi said. He reiterated that Mumbai hasn’t had a new AQI monitoring station after 2021, whereas Delhi had 25 stations in 2018 itself. This number had risen to 35 in 2020, and the capital now has 40 operational AQI monitoring stations.

“One can see how Delhi augmented the number of stations to get a vast network of data. Research institutions too, have been roped in to carry out regular studies,” he said.

London, Tripathi said, has as many as 110 monitoring stations, apart from sensor-based monitors. Considering the geography of Mumbai, it too, should have a similar number of monitoring stations, he said.

Over the past few years, 530 sensor-based AQI monitoring stations have been set up in 38 districts in Bihar, and 840 such sensors are being set up across 75 districts in Uttar Pradesh, he said.

“Earlier there used to be only 35 monitors in all of Bihar which allowed us to get a data point only every 5,000 sq km. Today, we have a sensor for every 300 sq km, and this is helping us get micro air shades of the state,” Tripathi added.

• “Also, in London, private vehicles are not allowed in certain places that are well connected by public transport. Mumbai too can look into this, now that the Metro network is becoming operational in a phased manner,” he said.

Dr Gufran Beig is Sir Ashutosh Mukherjee Chair Professor at the National Institute of Advanced Studies (NIAS) at the Indian Institute of Science (IISc), Bengaluru, and founder director of India’s System of Air Quality and Weather Forecasting and Research (SAFAR).

Dr Sachchida Nand Tripathi is Professor at IIT-Kanpur and Member of the Steering and Monitoring Committee of the National Clean Air Programme (NCAP). Dr Beig and Dr Tripathi, both winners of the Shanti Swarup Bhatnagar Prize, are India’s foremost air pollution experts.