70% rise in Mumbai’s pollution levels during first week of SeptemberUpdated: Sep 14, 2020, 23:44 IST
The drop in rainfall during the first week of September led to a sharp spike in the city’s air pollution levels, much before the end of the monsoon. Mumbai witnessed a 70% rise in particulate matter PM2.5 levels in Mumbai during the first week of September as compared to PM2.5 levels throughout monsoon and during the four phases of the Covid-19 lockdown, an analysis from January to September by the Council on Energy, Environment and Water (CEEW), a Delhi-based air quality research group, revealed.
The study showed Vile Parle, Andheri, Kurla, Sion and Worli were the five most polluted areas in Mumbai during the first week of September.
The air has suspended particulate matter (PM) of different sizes. Many of these are a complex mixture of dust, pollen, soot and smoke and they are hazardous. Of this, PM 2.5 is smaller, with a diameter not more than 2.5 micrometres. These are fine particles that can stay in the air for days or weeks and are small enough to invade the narrowest of lung airways.
According to CEEW’s analysis, the study period over nine months was divided into three phases — pre lockdown (January 1 to March 24), lockdown (March 25 - May 31) and monsoon or post lockdown (June 1 to September 10). The assessment, using data averages from 10 continuous air quality monitoring stations in Mumbai under the state pollution control board, showed: highest PM2.5 concentration for pre-lockdown was recorded on January 2 at 107.1 micrograms per cubic metre (μg/m³), 33 μg/m³ was the highest for the four phases of the lockdown on May 16 while 53.3 μg/m³ was recorded on September 6, the highest during the post lockdown phase so far. The study also identified the cleanest air days with 16 μg/m³ on March 11 (for pre-lockdown), 7.1 μg/m³ on May 29 (lockdown), and 4.8 μg/m³ on June 30 (during monsoon). The 24-hour safe limit for PM2.5 is 60 μg/m³.
“Mumbai has been experiencing good air quality for the past few months owing to monsoon and lockdown restrictions. With decreased rain during September first, air quality started worsening in the city. On September 6, readings showed a sharp spike in PM 2.5 levels, which was 70% higher than the PM2.5 levels during the entire lockdown and monsoon period,” said LS Kurinji, research analyst, CEEW, adding, “With the resumption of industries, constructions and other economic activities due to lockdown relaxations, anthropogenic (human-induced) emissions will soon worsen air quality. The city should start actively addressing its pollution sources to counter rising PM 2.5 levels.”
Independent experts said the lockdown and weather impacts are temporary factors for air quality improvement. “Cities like Mumbai have been working on their respective National Clean Air Program (NCAP) action plans, but there hasn’t been major emission reduction on ground yet. Current interventions are disaggregated with multiple state departments involved in different activities compromising accountability,” said Polash Mukherjee, lead (air pollution) Natural Resources Defence Council (NRDC) India.
The Maharashtra Pollution Control Board (MPCB) said as identified under the NCAP for Mumbai’s action plan, if two sources — vehicular pollution and re-suspended dust — are addressed, Mumbai would see much cleaner air as far as particulate pollution is concerned.
“While the Covid-19 associated lockdown did throw our usual lives out of gear, one silver lining was the reduction in air pollution. However, as restrictions have been eased, the rise in emissions will be visible,” said Sudhir Srivastava, chairman, MPCB adding, “For vehicles, the move towards Bharat Stage VI will help us remove not only nitrogen oxide, but PM. The issue of legacy vehicles remain, and we need to tackle that. Secondly, the use of water sprinklers, vacuum sweeping, having more green spaces, paving of roads as mandates issued to the civic body to arrest re-suspended dust. Work on this is going on and it should show results soon.”