Rejecting allegations that the Delhi government manipulated air quality data, the Central Pollution Control Board (CPCB) on Wednesday said that monitoring stations are automated and no human intervention is possible in the calculation and monitoring.
The Delhi government has been accused of spraying water to lower dire readings, especially in monitoring stations, and even switching them off during peak pollution periods.
"The monitoring and data collection are automated. The stations generate data every 15 minutes, and AQI is calculated every hour, following which the average AQI is generated. These stations are not manual, and hence any kind of human intervention or manipulation is not possible," CPCB Chairman Vir Vikram Yadav told reporters.
The air quality in the national capital remained in the 'very poor' category on Wednesday morning.
With an AQI reading of 335, this is the second consecutive day of 'very poor' AQI.
Yadav said the monitoring stations have been set up after the locations were scientifically studied, responding to allegations of sprinkling water around the monitoring stations.
Delhi has 39 Continuous Ambient Air Quality Monitoring Stations (CAAQMs), the highest for any Indian city. According to a report by News Laundry, the placement of the monitoring system leaves out 65 per cent of the national capital without reliable air quality estimates.
The Central Pollution Control Board’s (CPCB’s) 24-hour bulletin placed Delhi in the “very poor” category on November 18 after recording AQI of 374.
A Swiss air quality firm listed Delhi among the “top 10 most polluted cities in the world,” calling it the “most polluted major city” on October 14.
There was a brief respite from the toxic air on Sunday and Monday; however, the air quality slipped back to 'very poor' on Tuesday.
Earlier, the Aam Aadmi Party (AAP) had alleged that the data from the government's air quality monitoring stations was being manipulated, and the applications on people's mobile phones were receiving data from the manipulated data.
AAP Delhi chief Saurabh Bhardwaj claimed MCD trucks sprinkled water "day and night around" a few pollution monitoring stations to tamper with the data.
Shiv Sena (UBT) leader Aaditya Thackeray had also alleged that there were attempts to hide real AQI numbers and termed it "worrisome".
"The pollution in Delhi is worrisome. What is more worrisome is the strategies made to hide the real AQI numbers. What problem do the Union and state government have to accept the situation and bring about socio-political consensus on climate action?" he had said in a post on X.
Delhi Chief Minister Rekha Gupta had also defended the air quality monitoring system last month, rejecting allegations of manipulation.
(With inputs from PTI)