26 October,2026 11:10 AM IST | Mumbai | Aditi Alurkar
Hazy skies and poor visibility at Chowpatty on Sunday. Pic/Ashish Raje
Alarmed by alleged discrepancies in air quality index (AQI) monitors at construction sites in Mumbai, the Awaaz Foundation has written to the BMC commissioner and the Maharashtra chief minister, seeking urgent checks. The foundation monitored displays at six to seven construction sites across Bandra and Khar 230 times over 38 days, comparing their readings with those from nearby monitoring stations.
The first phase of monitoring took place between March and May, and the second between September and October. From March 23 to May 5, the foundation recorded readings displayed on boards outside construction sites and compared them with those from the Central Pollution Control Board's (CPCB) monitoring stations in Kherwadi and BKC.
An AQI monitor at a construction site on Hill Road, Bandra, displaying a PM2.5 reading of zero, a discrepancy flagged by the Awaaz Foundation. Pic/By Special Arrangement
In its report, the foundation said some construction-site boards displayed zero PM2.5 levels. On other occasions, PM2.5 and PM10 readings were in single digits even when CPCB monitors recorded higher levels. Some boards displayed question marks or dashes instead of readings. For September and October, foundation compared construction-site readings with AQI (US) readings, which it said were significantly higher.
"PM2.5 is the dust fine enough to reach deep into the lungs and bloodstream. These displays are meant to warn residents, and no one is held accountable for them," wrote Sumaira Abdulali of the Awaaz Foundation.
The foundation has asked the civic body to calibrate and audit monitors at every construction site and publish real-time, time-stamped PM2.5 data online. It has also sought a dedicated website for live readings, the deployment of air-pollution monitoring vans and action against faulty display boards.
"We understand that the BMC has said it will integrate the readings from these site monitors into its official findings, so that local data becomes part of the city's air-quality picture. We welcome that intent. But unless the data is first certified as correct, using calibrated meters, this exercise will be meaningless," Abdulali wrote.
She said residents rely on local display boards to decide whether to step outdoors or allow their children to play outside, and that incorrect readings could mislead people concerned about pollution.
When mid-day contacted the BMC, AMC Avinash Dhakne said monitors at open construction sites could malfunction. He added that the civic body's dashboard tracks the data and that officials had been instructed to ensure faulty monitors were repaired within three days.
"Moreover, ambient AQI and these low-cost sensors cannot be compared. The purpose of construction site sensors is to help the BMC with âhotspot monitoring'. When several such construction site boards in the same locality display high numbers, our officials intervene immediately. Mumbai has been recording moderate AQI between 100 and 120," Dhakne said. He added that the BMC was working on integrating artificial intelligence into its dashboard to automate the detection of such cases.
April 13
PM2.5 was displayed as zero near Pali Hill
April 24
Both PM2.5 and PM10 were displayed as zero near Pali Hill
