While Delhi has been recording a prolonged period of poor Air Quality Index (AQI) for more than a month now, Mumbai's AQI continued to linger within the moderate range. On Tuesday, Mumbai's overall AQI readings stood at 108 in the Central Pollution Control Board (CPCB) portal which is regarded as "moderate", while that of Delhi stood at 460 which is regarded as "severe". AQI readings between 0-50 are regarded as good, 51-100 is regarded as satisfactory, 101-200 is regarded as moderate, 201-300 is regarded as poor, 301-400 is regarded as very poor and above 400 is considered to be severe. In 2023, Mumbai's AQI breached the 200 mark and shot up to the poor category during October, a month before the Diwali when the city's AQI usually goes south due to bursting firecrackers and onset of winter. Later, following a spell of unseasonal rains during November last year, the AQI improved marginally. However, this year the city's AQI continued to stay within the moderate category for more than a month now with the city's overall AQI readings standing between 120-150. Experts have attributed the current condition to the change in wind direction and construction work of multiple infrastructure projects being completed. Gufran Beig, chair-professor of National Institute of Advance Sciences (NIAS), said Mumbai's AQI quality is dependent on the movement of sea breeze. "Unlike Delhi which is landlocked, Mumbai is a peninsular city with Sea from three sides. As a result, wind reversal takes place every 7-10 days, which blows away the suspended particulate matter in the air, leading to better AQI," Beig said. "However, in Western and Central India, large scale stubble burning is done and there could be a possibility that those pollutants can travel towards Mumbai in the days to come, so we shouldn't keep our guard down and continue to keep our emission levels in check," Beig stated. The CPCB's portal also showed that even Mumbai's overall AQI readings stayed in the moderate category, several pockets continued to record "poor" air above 200. For example Malad, Deonar and Bandra (East) recorded seven days of "poor" AQI for each day in November, Sewri recorded six days of "poor" AQI and two days of "very poor" AQI, and Worli recorded five days of poor AQI. Bhagwan Kesbhat, director of Waatavaran Foundation, said that multiple locations continue to record poor air due to several localised factors. "Mumbai's AQI has comparatively improved in the last two years given civil works for a lot of infrastructure work are now over. For example, the Coastal Road and Atal Setu is now complete and most of the metro work construction is now happening underground. This has resulted in in an improvement in the city's overall AQI, however the emission load continues. The PM 2.5 levels recorded even now is much higher than the WHO standards and this PM 2.5 is more fatal to human beings considering they can easily enter the human body through the nose," Kesbhat said. "Several pockets in Mumbai are showing varied AQI trends. For example, areas like Chembur and Govandi are consistent in recording poor air as they are home to refineries, industries and also the landfill. Worli and Sewri areas are impacted due to a slow wind pattern. Also there's the local emission load. Therefore, there's a need for localised analysis of AQI in Mumbai considering the city's complex geographical distribution," he added. The civic administration has mandated that action will be taken against fire wood being burned in the open, solid waste in public places as well as against contractors and infrastructure firms who violate dust mitigation measures. Mumbai's municipal commissioner and state appointed administrator, Bhushan Gagrani has also instructed the ward officials to mandate the installation of CCTVs at every construction site to record if all dust mitigation norms are being followed well.
