A South Gujarat University professor, requesting anonymity, said all it takes is erection of a tower and a plastic device containing sodium or calcium hypochloride.

The liquid will absorb the gas when the discharge is at its peak and with the use of high pressure liquid chromatography and gas chromatography the identity of the gas could be established in as less than 10 minutes, he claimed.

He said it was surprising that the GPCB officials, who had both the instruments at their office, did not do it earlier. He said the gas could be ethyl mercaptan, actually a chemical, which is mixed with liquefied petroleum gas to find out leakage. Ethyle mercaptan is so strong that only one part of it can spread in 30 billion parts of the air. When contacted, GPCB regional director J B Patel admitted that the board had the facility but it was being used to detect other gases in the normal course. Only on Wednesday, the collector had formed a 12-member committee with a representative each from 10 major industries in the region. Besides Patel, SMC's chief fire officer G M Kothwala have been included on the committee.

Patel said the committee would meet on Saturday. He claimed he had identified highly affected areas and decided to place instruments atop high-rise buildings to monitor the gas leakage. He said the gas indeed was ethyle mercaptan.

It maybe mentioned that all the three major industries, who use the chemical, have washed their hands of saying it was not emanating from their units. The SGU professor hinted that the source could be one of the industries in Hazira.

When the wind direction changes in the evening the impact of gas leak is felt. The police and fire brigade received several frantic calls on Wednesday night when complained of burning sensation in the eye and other irritations.

Meanwhile, the Sardar Patel Sewa Samaj has threatened to undertake a mass movement programme in protest against the alleged incapability of the administration to bring the accused to book.