Mumbai AQI readings differ across sources; officials say trust the government's SAMEER app

Different sources are reporting different AQI figures for Mumbai's air quality, leaving people confused. Officials say the Central Pollution Control Board's (CPCB) SAMEER app is the official platform and people should rely on it.

According to officials, the app is more dependable because it draws on a large network of CAAQMS stations that measure air quality continuously. However, a check found that even on the SAMEER app, data from nearby stations run by two government bodies shows considerable differences. The two bodies are the Maharashtra Pollution Control Board (MPCB) and the Indian Institute of Tropical Meteorology (IITM). IITM is an autonomous institute under the Union Ministry of Earth Sciences.

In many cases, IITM stations recorded a higher AQI than nearby MPCB stations. When data for 4 pm on Wednesday was compared, the gap was seen at five locations.

An MPCB official said the board has also noticed the difference in readings. The official said the board's stations are inspected regularly. "I too am seeing this trend in the SAMEER data, that IITM stations are showing a higher AQI than ours. We believe our maintenance is fully in order, and because of quarterly checks we are confident of the accuracy of our data. Given how close these stations are, there should not be this much difference in AQI. There could be some calibration problem at the IITM stations," the official said.

An IITM official firmly denied any such problem. "The calibration and maintenance of all AQI monitoring stations under IITM were checked just before Diwali. There is no problem on our side," the official said.

An MPCB official also explained why SAMEER is preferred. Speaking on condition of anonymity, the official said that compared with private platforms, SAMEER gives a fuller picture of Mumbai's air because it has more monitoring stations. In the official's words, "Its stations have a broad base, better representation of areas, and are installed in open surroundings. Private companies have fewer stations, so they have less data. Their sensors do not meet CPCB standards and are often unregulated and cheaper. Setting up one of our stations alone costs about Rs 1.5 crore, followed by regular maintenance. All this is to improve the accuracy of the data."