The AQI value recorded by the Chakala monitoring station was alarmingly high on October 19 and October 20. The MPCB alleged that the station’s location is “problematic”. The continuous ambient air quality monitoring station (CAAQMS) at Chakala was set up and is run by SAFAR, a national initiative under the Indian Institute of Tropical Meteorology (IITM).

While all other stations set and manned by IITM/SAFAR and MPCB have been recording AQI readings in the range of moderate/poor to very poor category, the station at Chakala on October 20 recorded AQI in the severe category (above 400). On October 20, the Central Pollution Control Board's (CPCB) SAMEER app displayed an AQI value of 423 for the IITM/SAFAR-run station, whereas SAFAR's own app reported a higher value of 560 for the same station.

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MPCB Speak

V M Motghare, MPCB's joint director, (Air Pollution Control), told mid-day that Chakala station was not operating properly and it had not been opened for the past year. “Also, a huge marble-cutting factory is located next to it. It’s not our station,” he said. Sharing the pollution control body's preliminary observation from a visit to the Chakala station, Motghare stated.

“The CAAQMS is located on a soil playground where natural dusting occurs. At its rear, a marble cutting is carried out at approximately 10 metres. Since the past one year, no one has opened the CAAQMS for operations and maintenance. Thus, no calibration must have been carried out by CAAQMS.” According to MPCB officials, only a wall separates the marble-cutting unit from the monitoring station and dust emissions from the unit and a neighbouring playground inevitably cause elevated AQI values.

SAFAR’s reaction

SAFAR/IITM in an email reply to mid-day stated: “This is not correct. The CAAQMS is under maintenance and regularly calibrated. It is true that there are many sources emitting dust near the Andheri station resulting in comparatively high values. Anthropogenic activities have increased over the years and it is for the BMC to prevent such activity near the station.” About the higher AQI value at the Chakala station, a SAFAR official said, “There could be some transient technical problem with the instrument that at times occurs with any electronic equipment.”

The MPCB had previously raised concerns about the accuracy of AQI readings at its air monitoring stations and their locations. In January, the authority initiated a request to relocate the nine monitoring stations administered by SAFAR. The basis for this request was that these stations were deemed inadequate in accurately reflecting Mumbai’s ambient air quality.

Pivotal meet

A pivotal meeting between MPCB and BMC was held on January 12, during which the MPCB formally presented their proposal to relocate SAFAR’s monitoring stations. In addition, officials claimed that SAFAR’s CAAQMS installations are placed in areas known for higher traffic-related emissions in comparison to other locations. They stated that this configuration fell short of providing a precise portrayal of the overall air quality situation.

To this, SAFAR replied: “SAFAR has been providing AQI in Delhi, Pune and Ahmedabad and no allegations have been made so far. The MPCB’s statement is not based on a thorough analysis of data from all the stations for comparison. It is only a subjective opinion.” To cross-examine SAFAR's AQI readings, MPCB stationed a continuous ambient air quality monitoring van at Govandi on Wednesday.