The board which is monitoring the air quality in eight stations under the national air monitoring programme of the Government of India, said the overall air quality in the state is still rated as "good".
"We found that the overall air quality is under the category 'good', the calculations of which is done as per standard procedures prescribed by the Central Pollution Control Board," board's senior scientist Dr Battinola Nongbri told PTI.
Till last year when the board had its station in a commercial hub in Khyndailad area of the city, the particulate matter level (dust and other solid emissions) of only that station used to exceed the prescribed standards, the official said.
Asked about the reasons, Dr Nongbri said vehicular exhaust, re-suspension of traffic dust and construction activities are the major factors contributing to the pollution level at Khyndailad area.
The only drawback in controlling pollution from vehicles is the absence of pollution testing stations set up for diesel-powered heavy vehicles such as trucks and buses and as such they are running without any pollution check, an official of the state transport department said.
Though the board is running a small testing station at its office here at Lumpyngngad, it is not possible for the board to issue environment green/red certificates to all vehicles plying in the state, Nengnong said.