Mumbai’s air pollution monitoring network has come under scrutiny after sensors recorded widely differing readings at nearby locations, including an unusually low Air Quality Index (AQI) of 16 at a construction site in New Cuffe Parade.
On Thursday, the city’s AQI ranged from 57 in Malad to 153 in Worli. At the New Cuffe Parade site, the sensor registered PM2.5 levels of 5.6 and PM10 levels of 11.1. Across the road, a ready-mix concrete plant recorded readings of 49 and 60, while another nearby monitor reported PM2.5 at 25.1 and PM10 at 6.3.
Additional municipal commissioner Avinash Dhakane questioned the unusually low figure. “AQI 16 is practically impossible under the prevailing conditions. Such a reading could indicate a calibration issue, sensor error or manipulation,” he said.
The discrepancies have raised concerns about the accuracy of data used to guide the Brihanmumbai Municipal Corporation’s (BMC) pollution-control measures. The civic body has announced plans to deploy artificial intelligence-based analytics to assess 3,000 sensors at construction and infrastructure sites, identify pollution hotspots and detect violations.
Dr Sagar A Marathe, assistant professor at Somaiya Vidyavihar University’s School of Basic and Applied Sciences, said local weather, wind patterns and emission sources could cause variations. However, significant differences require investigation.
“Massive discrepancies could indicate low-quality sensors, power or voltage fluctuations, improper calibration, or incorrect placement and shielding. Sensor installation sometimes appeared to prioritise displaying readings over ensuring equipment functioned correctly.”
BMC guidelines require sensors to be calibrated every two months, compared with reference-grade monitors and checked periodically. Dust accumulation and humidity can also lead to under-reporting. The civic body has empanelled 18 agencies to install sensors and instructed officials to remove repeatedly faulty equipment. Inspection teams have been visiting construction sites since October 1.
Environmental expert B N Kumar, director of NatConnect Foundation, warned that inadequate supervision could permit manipulation. “It’s possible to tamper with the meter settings. There should be standardisation of meters and BMC must check whether readings displayed are accurate,” he said.
Similar discrepancies were reported at two nearby construction sites in Sewri and at a Kamothe site in Navi Mumbai, reinforcing concerns about monitoring standards and data reliability.
Source: Times of India
