Mumbai’s air quality worse than Delhi; AQI stays ‘poor’

In the absence of wind, which helps in dispersing particulate matter, and because of ongoing infrastructure activities across the city, AQI levels for most of the previous week hovered between ‘poor’ and ‘very poor’. With wind speed picking up over the weekend, there was some improvement in pollution levels.

Mumbai: In an alarming indication of pollution levels in the city, the week began with Mumbaikars breathing more polluted air than even Delhiites. Although better than last week, Mumbai on Monday recorded an overall Air Quality Index (AQI) of 225 which falls in the ‘poor’ category, compared to Delhi which recorded a ‘moderate’ AQI of 152, as per the System of Air Quality Forecasting and Research (SAFAR).

Mumbai’s poor AQI had figured in the talks between G20 Sherpa Amitabh Kant and municipal commissioner I S Chahal some days ago. While Chahal blamed refineries and the Tata Power plant for major pollution, Kant on Monday said that the emission of sulphur-dioxide refineries was within prescribed norms. Kant, who also spoke to Union petroleum secretary M M Kutty, said that two refineries in the Mahul area would have to ensure that they reduced sulphur emissions. (Bhushan Koyande/HT Photo)

Although the SAFAR data showed that Mumbai’s AQI was worse than Delhi’s, the daily 4 pm bulletin by the Central Pollution Control Board (CPCB) showed the contrary: Mumbai at 168 (moderate) and Delhi at 218 (poor). The discrepancy was on account of the fact that SAFAR has monitoring stations at nine locations in the city while CPCB calculates the overall AQI based on 18 locations. Delhi, on the other hand, has 36 air quality monitoring stations.

Mumbai’s poor AQI had figured in the talks between G20 Sherpa Amitabh Kant and municipal commissioner I S Chahal some days ago. While Chahal blamed refineries and the Tata Power plant for major pollution, Kant on Monday said that the emission of sulphur-dioxide refineries was within prescribed norms. Kant, who also spoke to Union petroleum secretary M M Kutty, said that two refineries in the Mahul area would have to ensure that they reduced sulphur emissions.

The G20 Sherpa also said that apart from refineries, the burning of garbage in the Deonar dumping yard had to be stopped, and Tata Power needed to use cleaner methods for power-generation.

In the absence of wind, which helps in dispersing particulate matter, and because of ongoing infrastructure activities across the city, AQI levels for most of the previous week hovered between ‘poor’ and ‘very poor’. With wind speed picking up over the weekend, there was some improvement in pollution levels.

Gufran Beig, founder & project director, SAFAR, said that after Cyclone Mandous, the windspeed was back to being calm. “There are no clean winds coming from the sea so local emissions continue to get trapped,” he said. “Cold conditions in the north are also likely to increase pollution levels in Mumbai.”

Beig said the La Nina condition, which is related to large-scale wind circulation, in its unprecedented third year could be an early sign of climate change. “La Nina changes the wind circulation pattern, due to which winds become calm,” he said. “These calm winds with prevailing cold temperatures result in the accumulation and trapping of local emissions, which otherwise would have got dispersed due to a faster wind speed.” Officials from SAFAR have advised citizens to avoid going to congested areas and to wear a mask if at all they had to go there.

Environmental scientists said that dust pollution due to construction activities and slow-moving traffic across the city are two major causes for the drop in air quality. “Large-scale open handling (storage and transportation) during construction gives rise to a very high level of fine dust. The sources are not easy to count and regulate. We need ‘hyper local’ tracking to act for better air quality,” said Rakesh Kumar, former chief of the National Environmental Engineering Research Institute.

Explaining ‘hyper local tracking’, Kumar said that sensors needed to be installed on a few vehicles that could move around locations to help pinpoint the source of air pollution. “Mitigation measures can then be chalked out,” he said.

Air quality in Malad, which stood at 311, was the worst, followed by Mazgaon and Chembur (303) and Andheri at 300. The Bandra Kurla Complex (269) came under the poor category, whereas there were four locations in the moderate category: Colaba (173), Bhandup (125), Borivali (111) and Worli (101). Prolonged exposure to poor air can lead to a range of respiratory and cardiovascular problems.