Mumbai's AQI data likely being tampered with, alleges scientist

Mumbai: A leading air pollution scientist on Thursday claimed that the air quality data being captured by most continuous ambient air quality monitoring stations (CAAQMS) in an around Mumbai are being tampered with.

According to a report in Hindustan Times, the scientist alleged that over the past five years, data of PM 2.5 and PM 10 from majoritarian CAAQMS are being evidently tampered with.

Leading scientist says data collected by CAAQMS is being manipulated

Reportedly, these allegations were made during media interaction which was organised by Clean Air Mumbai--a group of citizens, civil society groups working toward tackling air pollution--on effectiveness of smog towers.

The scientist who did not want his name to be revealed, said that the visualisation of PM10 and PM 2.5 data showed that for most sites, PM 2.5 values are lesser compared to PM 10 which is theoretically correct.

The scientist then explained that it is an incredibly ideal situation and there are no outliers when data is mapped on scatter plot.

Keeping in mind the influence of fluctuating outdoor atmospheric conditions and occasional instrument malfunctioning, he said, there ought to be days when value of pollutant PM 2.5 is higher than that of PM10.

The scientist also pointed out that there is only one monitor at Pimpaleshwar Mandir in Thane where the data is not manipulated to show it is in line with theory.

The report quoted another air quality scientist from Delhi as saying that such manipulation of data can be done for a multitude of reasons--it could be done to make up for poor maintenance, lack of routinely caliberating monitors or due to malfunctioning of a sensor for particular pollutant. They added it could also be to simply present cleaner data for whatever reason.

SAFAR's director says data from their monitors cannot be tampered with

When asked about the possibility of SAFAR's monitors being tampered with, Gufran Beig, the founder director refuted the claims. SAFAR has nine monitors in Mumbai and Navi Mumbai.

Beig was quoted as saying that SAFAR's data is not in public domain and cannot be downloaded or analysed; he further said that CAAQMS the scientist referred to could be those operated by MPCB but refused to comment on analysis' quality.

Ramifications of the claims being true

Senior scientists were quoted saying that the allegations, if proven true, could refer to a range of possibilities and one among them would be that the monitors have not been functioning for both pollutants-- PM 2.5 and PM 10.

The Delhi-based scientist said that agencies could only be monitoring value of one parameter and back-calcualte for others. They suggested it could be measure to cut costs or the agencies are manipulating data because the monitors may not be working.

The other possibility, the scientist said, is because of the dynamic coastal atmosphere of Mumbai, there could be multiple outliers in data which are 'cleaned up' for data management and future analysis.