No tampering possible in calculation, monitoring air quality data: CPCB

New Delhi: The Central Pollution Control Board (CPCB) on Wednesday rejected allegations of manipulation of air quality data and said the monitoring stations are automated and no human intervention is possible in calculation and monitoring.

Delhi government has been accused of spraying water around air-quality monitoring stations to lower dire readings and even switching them off during key pollution periods - for instance, when firecrackers increased the pollution load during Diwali in October.

"The monitoring and data collection is 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 here.

Responding to a query about allegations of sprinkling of water around monitoring stations to manipulate air quality data, Yadav said, "The monitoring stations have been set up after their locations were scientifically studied".

Delhi has 39 Continuous Ambient Air Quality Monitoring Stations (CAAQMs), the highest for any Indian city.

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. There was a brief respite from the toxic air on Sunday and Monday; however, the air quality slipped back to 'very poor' on Tuesday.

Aam Aadmi Party (AAP) had alleged that most applications on people's mobile phones were taking data from the government's air quality monitoring stations, while the data of these stations is being manipulated.

AAP Delhi chief Saurabh Bhardwaj had claimed that MCD trucks were sprinkling water "day and night around" a few pollution monitoring stations.

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.