MUMBAI, Nov. 21 -- In light of rising air pollution with the advent of winter, Mumbai's civic body has sounded a warning for construction sites and industries: if the air quality index (AQI) of a ward stays consistently above AQI 200 ("Poor") for three days or more, all construction and industrial activity will be stopped under the Graded Response Action Plan (GRAP 4). Flying squads have been constituted to enforce these regulations. Since November 13, for the past seven days, the 24-hour AQI of Deonar has consistently been over 200, with spikes taking the hourly AQI even higher. On Thursday, too, the 24-hour AQI was 271. Mazgaon, another locality consistently in the "poor" category, has had its AQI over 200 since November 16, for five days now. Thursday saw it reach 225, due to the PM2.5 pollutant. "Whether or not to apply GRAP-4 is a decision the BMC will have to take, considering the outlook of the entire ward, what are the macro factors contributing to it, and if all measures of suppressing air pollution have failed," said a senior official with the BMC's Environment and Climate Change department. "For instance, in Deonar, local factors such as garbage burning lead to higher AQI readings, but these conditions may not apply to the entire ward, to warrant serious action," he said. Apart from issuing notices to violating construction sites based on the 28-point air pollution mitigation guidelines released in 2024, the BMC has also constituted flying squads at the ward level. Each squad will include two civic engineers and a police officer with a vehicle tracing and monitoring system (VTMS). "The squads are responsible for enforcing air pollution guidelines at construction sites, as well as checking for open burning, etc," said the official. On Wednesday, checks were conducted on over 20 construction sites in Prabhat Colony, Santacruz east, of which eight were given show-cause notices, asking them to comply with the guidelines within 7 days. On Tuesday, the BMC fined Sanghvi Realty and Ambit Developers of Prabhat Colony Rs.10,000 for violating the guidelines, among other things. Explaining why AQI is at a high in Mumbai, Sunil Dahiya, founder and lead analyst at Envirocatalysts, said, "Low temperatures, very low wind speeds of 7 to 10kmph, and wind direction from the landward side are contributing to an accumulation of pollutants in Mumbai." He added, "But we must keep in mind that local conditions near AQI monitors can skew figures, making the situation seem better or worse than it is." Dahiya noted that enforcing GRAP-4 can be a useful tool. "But they cannot be an alternative to comprehensively reducing emissions at source across the year."...