‘Mumbai’s air quality data likely being tampered with’

BKC *As per the analysis of Central Pollution Control Board (CPCB) data by the Delhi-based Centre for Science and Environment (CSE), published this week, in a report titled ‘Winter pollution in megacities: The growing crisis outside Delhi’.

INDEPENDENT EXPERTS WERE RELUCTANT TO COMMENT ON THESE ALLEGATIONS WITHOUT THEIR OWN ANALYSES

MUMBAI: A leading Indian air pollution scientist on Thursday cast doubts over the quality of air pollution data captured by most continuous ambient air quality monitoring stations (CAAQMS) in and around Mumbai. The scientist has alleged that over the past five years, PM2.5 and PM10 data from a majority of 23 CAAQMS are being evidently tampered with, though he chose to not venture any speculation as to the authority responsible for the same.

These allegations were made during a public plenary session organised on Thursday evening by Clean Air Mumbai (a network of citizens and civil society groups working towards tackling air pollution in the city) on the effectiveness of smog towers. However, Hindustan Times is not identifying the scientist at their request, as they expressed a fear of reprisal.

“Visualisation of PM10 and PM2.5 data shows that for most of the sites, PM2.5 values are lesser compared to PM10, which is theoretically correct. That’s the thumb rule. However, this is an incredibly ideal situation, and there are no outliers when the data is mapped on a scatter plot,” said the scientist.

“Considering the influence of a fluctuating outdoor atmospheric conditions and occasional instrument malfunctioning, which is normal, there must always be some instances when PM2.5 reading exceeds that of PM10. There is only one CAAQMS at Pimpaleshwar Mandir, Thane, where the data

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2020-21

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2022-23 does not seem perfectly in line with what theory dictates,” added the scientist.

To be sure, the motivation behind the alleged tampering is likely not to present a picture of better air quality, but to give the impression that the CAAQMS are indeed working as they should be, said the expert, and other independent scientists who spoke to Hindustan Times.

“Hypothetically speaking, such manipulation can be done for multiple reasons. For example, to make up for poor maintenance and lack of frequent calibration of monitors, to circumvent the malfunctioning of a

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Navy Nagar, Colaba sensor for a particular pollutant, or to simply present ‘cleaner’ data within a preferred range of numbers, for whatever reason,” said an independent air quality scientist from Delhi, who did not want to be quoted.

Gufran Beig, founder-director of SAFAR -- which operates a network of nine CAAQMS in Mumbai and Navi Mumbai — refuted the possibility of SAFAR’s monitors being tampered with.

“Our data is not in the public domain and cannot be downloaded and analysed in this manner by anyone. The CAAQMS being referred to by this scientist are almost certainly those which are operated by the MPCB, though I will not comment on the quality of their analysis.”

If true, the senior scientists say these allegations could imply a range of possibilities. One, that the CAAQMS in question are not monitoring for both parameters, i.e., PM2.5 and PM10.

“They may only be monitoring for one, and then back-calculating for the other parameter. It could be a cost cutting measure, or maybe the monitor is simply not working and they are finding a way around it, but it is essentially manipulation,” said the independent scientist from Delhi.

Another possibility, they said, is that Mumbai, with extremely dynamic coastal atmosphere is throwing up too many outliers in the data, which are being ‘cleaned up’ for easier data management and future analysis.

Multiple independent experts were reluctant to comment on these allegations without first carrying out their own analyses. VM Motghate, joint director (air), MPCB, did not respond to requests for comment, as did Pravin Darade, member secretary, MPCB.