CHENNAI: A suspected sulphur dioxide gas leak, allegedly from Chennai Petroleum Corporation Limited (CPCL), has sparked alarm in several densely-populated residential localities in Tiruvottiyur and Manali.
After residents complained of a pungent odour similar to that of LPG gas multiple times during the day, particularly in the morning and evening, for the past 10 days, the Tamil Nadu Pollution Control Board (TNPCB) has issued a slew of directions to the company to monitor ambient air quality.
The concentration of the 'unidentified' gas in the air is so intense that even healthy people have started complaining of breathlessness. Residents of Jothi Nagar, Sathyamurthy Nagar, TKS Nagar and a few areas in Manali, all located within a 2-3 km radius of CPCL, have been facing the issue.
GR Alfred Rupak, correspondent, St Antony’s Matriculation Higher Secondary School, Jothi Nagar, Tiruvottiyur, told The New Indian Express, "We started experiencing it from July 5. It smells like LPG gas. Our students reported suffocation and had to come out of classrooms."
"Initially, we thought there was an LPG leak in our kitchen or in the neighbourhood but we later realised it was some chemical gas leak. At times, the smell is mild, but this morning at 9 am it was so strong that I felt suffocated," he said.
A joint chief environmental engineer of TNPCB told The New Indian Express last week that the board had detected a sulphur dioxide leak from CPCL. "We have detected and inventoried it. A consignment of crude that CPCL is believed to have received from Russia came with high sulphur content. During processing, some amount of sulphur dioxide escaped into ambient air. A resident from Tiruvottiyur complained and we addressed it. CPCL was instructed not to use that particular crude oil for processing and comply with all norms," he said.
Since fresh complaints were received on Thursday morning, the TNPCB official said a 24-hour ambient air quality survey was initiated to know the exact gaseous compound that is troubling the residents and the source of it.
"The smell of sulphur dioxide and LPG gas is slightly different. So, advanced personnel samplers have been deployed to accurately detect the gas. It would either be LPG, sulphur dioxide or mercaptans (an odourant)," he said.
A senior official of CPCL, however, rejected the allegations of a possible sulphur dioxide leak from the plant. "If that is the case, our workers would have felt it first. We are assisting TNPCB officials to identify and detect the exact source of the leak and the type of gas," he said.
CPCL officials also denied receiving crude oil with high sulphur content. "We received the same crude and there was no change in processing it. The crude generally comes from Mumbai and Middle East," he said.
The official said he had to check if any consignment was received from Russia.
The recommendations made by the TNPCB to the CPCL include installation of Online Continuous Emission Monitoring Systems (OCEMS) to comply with parameters for hydrogen sulfide and sulphur dioxide in the stacks attached to all the Sulphur Recovery Units (SRU's) and to connect the same with the Care Air Centres (CAC) of TNPCB and CPCB (Central Pollution Control Board).
The CPCL was also asked to ensure enough incinerators are attached to SRUs and emission standards are complied with. The existing SRUs were asked to achieve sulphur recovery efficiency of 98.7% at all times as per the Union environment ministry’s notification dated March 18, 2008.
The CPCL refinery was directed to provide gas recovery system for the existing and newly installed flare systems so as to burn the excess hydrocarbons and acid gas in their furnaces/boilers without letting them into the atmosphere.
The company was also asked to install two Continuous Ambient Air Quality Monitors to check parameters such as PM10, PM2.5, SO2, NOx, CO, Ammonia, TVOC, and Benzene outside the premises in the upwind and downwind direction factoring in monsoon pattern in consultation with TNPCB officials. The monitors must be connected with the CAC, TNPCB & CPCB.