The staff operating the smog tower at Connaught Place here shut it down on Sunday over alleged non-payment of their salaries, according to sources.

However, an official of the Delhi government said that the Delhi Pollution Control Committee (DPCC) in December sanctioned funds to the project management consultant, NBCC (India) Limited, for the payment of salaries to the staff of Tata Projects Limited (TPL), who operate the smog tower.

“The staff of Tata Projects Limited raised concerns about delayed salary payments, and the Delhi government cleared the dues in December. The NBCC, responsible for disbursing funds to Tata Projects Limited, failed to do so due to non-submission of utilisation certificates,” the source said.

Sources said the DPCC will hold a meeting with the NBCC and TPL regarding the issue on Wednesday.

In 2021, two smog towers were installed in Delhi - one at Connaught Place under the DPCC and another at Anand Vihar under the Central Pollution Control Board (CPCB) - following directives from the Supreme Court.

The smog tower at Connaught Place was temporarily shut down based on unilateral directions from the chairman of the DPCC, Delhi Environment Minister Gopal Rai had claimed earlier. It was restarted in November following orders from the apex court.

According to the CPCB data, during the 2021-22 winter season, the smog tower at Anand Vihar reduced PM2.5 concentration by up to 17 per cent and PM10 levels by up to 27 per cent within a 100-metre radius.

Last year, the Delhi government said that the Connaught Place smog tower could decrease air pollution by 70 to 80 per cent within a 50-metre radius and by 15 to 20 per cent up to 300-metre radius.

In November, the DPCC informed the National Green Tribunal (NGT) that the two experimental smog towers in the city were ineffective in reducing air pollution. The operation of these costly giant air purifiers lacks merit, according to a report submitted to the NGT by the pollution control body. Nadita Moitra, a senior scientist at the DPCC, said in the report that the Rs 25-crore smog tower at Connaught Place, operational for two years, can only mitigate air pollution by up to 17 per cent within a 100-metre radius.

Considering Delhi’s vast area of 1,483 square kilometres, the pollution control body highlighted the need for more than 47,000 such towers, each costing Rs 25 crore for installation and requiring Rs 15 lakh monthly for operation and maintenance.