60% drop in pollution as Mumbaiites stay home during Janta CurfewUpdated: Mar 23, 2020 23:35 IST
The city witnessed a significant drop in both air and noise pollution levels across the city during the one-day Janta Curfew on Sunday which was called by Prime Minister Narendra Modi.
According to a report published by System of Air Quality Weather Forecasting and Research (SAFAR) on Monday, Mumbai recorded a 30% decline in oxides of nitrogen (NOx) and a 20% decline in particulate matter (PM2.5) on Sunday (March 22) as compared to peak levels on March 18. Maximum NOx decline was recorded at Andheri (25%) and Borivli (20%).
NOx is emitted during agricultural and industrial activities and the combustion of fossil fuels and solid waste.
On Monday, however, the pollutant-measuring indicator-air quality index (AQI) by SAFAR witnessed a marginal increase from 61 (satisfactory) on Sunday to 69 (satisfactory), on account of an increase in vehicular traffic despite the state’s directive of a lockdown in Mumbai.
“On March 18, there was high dust pollution in Mumbai’s air due to the wind pattern over the city and external sources. However, as vehicular movement reduced, a considerable declining trend has been observed. Under the current scenario, a further decline in all pollutants cannot be ruled out,” said Gufran Beig, project director, SAFAR.
Another analysis for Sunday saw the average concentration of PM2.5, PM10, and NOx falling to its lowest this year. NOx and PM2.5 levels fell by 60% and 62% respectively, compared to their concentrations on previous Sundays this month. All locations in the city reported PM2.5 air quality levels between 12 to 20 microgrammes per cubic metre (µg/m3) with the city average at 16µg/m3. The average PM2.5 concentration – or baseline pollution – in Mumbai was around 16µg/m3 against the safe limit for 24 hours at 60µg/m3. The PM10 concentration was 54µg/m3 against the safe limit of 100µg/m3.
These details were revealed as part of an assessment of the Central Pollution Control Board (CPCB) air quality data across 10 stations by independent research group UrbanSciences.
NO2 (nitrogen dioxide) levels were below 10µg/m3 at most locations including Powai, Worli, Colaba, and Borivli. However, locations such as the area around the international airport at Sahar, Sion, and Bandra had the worst NO2 air quality on Sunday.
“Reduced air and vehicular traffic at the airport area allowed NO2 levels to fall by 75% on Sunday,” said Sutaria, adding that the city-wide average NO2 level was recorded at 9.77µg/m3 as against the safe limit of 80µg/m3 for 24 hours.
NO2 pollution is a result of emissions from vehicles, industries, and all sources which burn fossil fuel.
On March 17, particulate matter reached twice the safe limit, with Kurla and Sion recording 24-hour averages 300% more than the prescribed PM10 safe limit. The airport area recorded 2.5-times the safe limits of 100µg/m3.
“Based on government notifications and continuous news updates on the Covid-19 outbreak on Tuesday, it can be inferred that almost 15 million Mumbai residents began frantic outdoor activities in anticipation of a lockdown, thereby contributing to worsening air quality conditions on Tuesday and Wednesday,” said Ronak Sutaria, founder and director, UrbanSciences.
Meanwhile, an assessment of real-time noise levels recorded and published on the CPCB website for 10 locations in the Mumbai Metropolitan Region (MMR), undertaken by anti-noise campaigner Awaaz Foundation, showed that noise levels across all monitoring stations were less than daily averages. For example, against the average of 98 decibels (dB) at Marine Drive on a normal day, the CPCB station recorded maximum levels at 78.9dB on Sunday. At Bandra, against normal readings of 99 dB, the area recorded 62.21dB, and Sion recorded 63.6dB against normal levels of 97.3dB. However, there was a marginal spike across all locations between 5pm and 5.15pm as people showed solidarity towards health and essential service providers by clapping and banging utensils.
“Noise levels on the day of Janta Curfew, when there was no traffic at busy Mumbai junctions, recorded a steep decline. Maximum noise levels, even at these noisiest spots of the city, were within daytime permissible limits at several places, including Bandra and Sion,” said Sumaira Abdulali, convener, Awaaz Foundation.