The state pollution control board has installed four continuous ambient air quality monitoring stations, also known as automatic air pollution monitoring stations, in Calcutta following a push from the National Green Tribunal.

The new stations will be linked to the national grid soon, an official at the board said.

The city earlier had only two automatic air pollution monitoring stations — at Victoria Memorial and on the Rabindra Bharati University campus on BT Road.

The new stations have been set up at the Birla Institute and Technical Museum (BITM) on Gurusaday Dutt Road, Indian Association for Cultivation of Science in Jadavpur, Administrative Training Institute in Salt Lake and Fort William.

Calcutta has as many as 16 manual air pollution monitoring stations but the data generated by automatic facilities are considered more authentic.

“Most of the new stations have started generating data. The data, however, are yet to be uploaded on the state board server or the national grid because of a problem in connectivity. We hope the problem will be resolved soon,” state pollution control board chairman Kalyan Rudra said on Sunday.

The machines, Rudra said, are procured from a French company and cost around Rs 90 lakh each.

The station at Fort William does not have too many polluting agents nearby. “It will measure the air quality in the absence of pollutants. The data from that station will help us put the data gathered from other stations in perspective,” Rudra said.

“The National Green Tribunal had in 2016 directed the state pollution control board to set up five more automatic air quality monitoring stations in Calcutta and Howrah. The order was based on a recommendation of the committee set up by the tribunal. It’s good that despite the delay, the board has set up four stations in Calcutta,” said green activist Subhas Datta, who has filed a number of cases related to air pollution.

The tribunal had said the new stations should come up “near Science City, Ballygunge Phari and Sector V”.

The station set up at BITM is close to Ballygunge Phari. However, the ones closest to Sector V and Science City are around 5km and 9km away, respectively.

Board officials pointed out that finding space to set up automatic air quality monitoring stations was a challenge.

City-based environmentalists stressed the need to set up automatic stations at congested places such as Moulali and Behala.