According to the World Air Quality Report for 2024 published by IQAir, a Swiss company that tracks global air quality, Byrnihat on the Meghalaya-Assam border is the “most polluted city in the world”. The annual average PM2.5 concentration in Byrnihat was 128.2 micrograms per cubic m (µg/m3), many times the World Health Organization’s annual air quality guideline of 5 µg In January this year, the Helsinki-based Centre for Research on Energy and Clean Air ranked Byrnihat the most polluted city in India, based on monthly average PM2.5 levels. Why is the air in this town, located in a region known for its scenic beauty, so bad? Town and its industries Byrnihat is located around 20 km from Guwahati and 65 km from Shillong, in Meghalaya’s Ri-Bhoi district, where the hills of Meghalaya descend into Guwahati. Over the years, Byrnihat has developed into a regional industrial hub. The residential town is in Meghalaya, and the industrial units surrounding it are in both Meghalaya and Assam. In Meghalaya, the industries are in the Byrnihat Export Promotion Industrial Park (EPIP); in Assam, they are in Tamulikuchi in the Kamrup Metropolitan district, along the national highway that runs through the town. The industries include those involved in the production of coke (fuel), cement, ferro alloys, and steel, and in distillation and brickmaking. They mushroomed in the area because of the proximity to coal reserves in Meghalaya and the large urban centre of Guwahati, as well as the supply of water from the Umtru river. The Meghalaya state Action Plan for Prevention and Control of Air Pollution was released in December 2024. It records 39 industrial units in Assam and 41 in Meghalaya in Byrnihat. Twenty units in Assam and five in Meghalaya are “red category” industries — identified by the Union Ministry of Environment and Forests as “heavily polluting” (including cement, distillery and fermentation, iron and steel, coke production). Fifteen units in Assam and 22 in Meghalaya are in the “orange category” (brick manufacturing, cement clinker grinding units), according to the Action Plan. Non-compliance with norms Meghalaya Chief Minister Conrad Sangma told the legislative Assembly last week that following surprise checks in industrial areas in Meghalaya in late January and early February, the state Pollution Control Board had served closure notices on seven units, and imposed environmental compensation on two others. The violations included “heavy emissions from chimneys due to non-operation of pollution control devices, ineffective pollution control devices, and non-transmission of online emission data”, the Chief Minister said. Assam Pollution Control Board chairman Arup Kumar Misra told The Indian Express that the board has served notices on several industries in its area. “There are industries there which are not following the rules… Many have the required devices which can trap pollutants but don’t use them because those are energy intensive and incur costs,” Misra said. Vehicles and topography Dr Ganesh Chandra Dhal of NIT Meghalaya, who has carried out research on air pollution in Byrnihat, pointed to vehicular emissions in the area. “This is an important transit point for vehicles. Material is loaded and unloaded from heavy diesel vehicles, many of which do not comply with tailpipe emission norms. Vehicles idle in congestion on the road. Besides PM2.5 and PM10, sulphur dioxide levels are also high in the area,” he said. A CSIR-NEERI team that surveyed the area in 2022-23 found that unpaved roads in the area aggravated road dust. Experts have also pointed to the area’s “bowl-like” topography. The surrounding hills inhibit the dispersal of pollutants in the air. “It is like a basin. While there are hills and high elevation on either side, the area itself has an altitude of only about 60 metres. It experiences a valley-and-basin effect, because of which wind speed is reduced. This may be impacting the transport of air out of here,” Dr Rajesh Bajpai, who teaches environmental studies at North-Eastern Hill University, said.
