India, Sept. 30 -- Haryana's air quality monitoring stations lying defunct for the past six months were finally restored to service on Monday, however, officials said in many cities like Gurugram, Faridabad, Karnal, Ambala and Charkhi Dadri, 12 to 15 of the 29 continuous ambient air quality monitoring systems (CAAQMS) kept on troubleshooting due to a technical glitch on Tuesday.

The advanced-sensor systems, which feed into the Air Quality Index (AQI), were shut statewide in January 2025 following a failure to renew the contract with private firms who were adamant on demanding exorbitant prices for their maintenance, according to officials familiar with the matter.

Notably, the contracts had expired in batches and the Haryana State Pollu...