“Deaths are caused normally by depletion of oxygen”

A simple method of agitating wells or tanks by lowering a bucket full of water before people enter them can avoid loss of lives, said forensic expert P. Chandrasekar.

Reacting to the death of seven workers in a dyeing unit in the SIPCOT industrial complex in Perundurai, he said despite his repeated requests, there was no effort to popularise the time-tested method of removing the heavier carbon-di-oxide or other such gases that over time replace oxygen in wells and tanks. “The deaths are caused normally by depletion of oxygen leading to asphyxiation. Carbon-di-oxide is not a poisonous gas. When you agitate the well, you can remove heavier gases,” said Mr Chandrasekar, who was associated in piecing together information in the Rajiv Gandhi assassination case. He said death of workers entering into wells to desilt during summer had become common.

“The vegetation deposited at the bottom releases carbon-di-oxide. This displaces the lighter oxygen and the worker entering the well dies of asphyxiation,” he said.

Mr Chandrasekar said “people could also lower a lighted candle in a bucket. Lack of oxygen would put out the candle. Villagers send down a fowl. They will enter the well only if the fowl survives for sometime,” he said.

In the case of dyeing units and other factories, he said that the nature of the gas formed inside could be assessed by lowering a bottle full of water. “Empty the bottle in the tank. The heavier gas will replace the water in the bottle. This can be analysed. It is an easy method to ascertain the nature of the gas inside,” he said.