At least 2,600 people were evacuated after a leak of hazardous gas at a chemical plant near the western Indian city of Mumbai on Monday caused a cloud of fumes to engulf surrounding areas, prompting emergency measures.
The leak occurred at an industrial facility in Boisar, about 100km north of the Indian financial capital. Authorities said the leak involved oleum, also known as fuming sulphuric acid, a highly corrosive industrial chemical used in the manufacture of detergents, dyes, explosives, and pharmaceuticals.
Fumes from the leak spread as far as 5km from the plant, prompting the evacuation of around 1,600 school students and more than 1,000 workers from nearby factories as a precaution.
According to a statement by the district administration, the leak came from a 2,500-litre “oleum day tank” at a factory operated by Bhageria Industries Ltd at about 2pm local time.
Oleum is a concentrated form of sulphuric acid that releases sulphur trioxide fumes on contact with air. Exposure can cause severe irritation to the eyes and the respiratory tract and, in high concentrations, chemical burns to the skin and the lungs.
Authorities said three people reported minor eye irritation and were receiving treatment in hospital. No serious injuries were immediately reported.
The cloud of white fumes spread rapidly due to wind conditions, causing panic among workers and residents in the industrial belt.
Palghar district collector Indu Rani Jakhar said the local disaster management plan was activated immediately.
“The leakage occurred from a 2,500-litre capacity oleum day tank. Due to the wind direction, the smoke spread to surrounding areas, impacting a radius of about 5 kilometres,” the administration said in a press release.
Teams from the National Disaster Response Force, the fire brigade, and experts from the Bhabha Atomic Research Centre were deployed to contain the leak. Officials said response teams initially struggled to reach the source because of the high concentration of fumes.
Chemical specialists and NDRF personnel eventually entered the premises using self-contained breathing apparatus. Sandbags were placed around the leaking tank to help suppress the fumes.
Police superintendent Yatish Deshmukh urged residents not to panic, while the collector appealed to people to remain indoors and follow official instructions.
The cause of the leak was not immediately known and an investigation was expected to be started.
Industrial accidents involving toxic chemicals near-periodically raise concerns in India about safety standards in rapidly expanding manufacturing hubs located near densely populated areas. Boisar is part of one of Maharashtra state’s major industrial corridors, housing chemical, pharmaceutical and engineering plants.

