At least 52 people were hospitalised after an ammonia gas leak late on Tuesday night in a fertilizer plant in Chennai’s Ennore area, an area that was already devastated by an oil spill earlier this month.

Read here: Ammonia gas leak in Chennai’s Ennore, several hospitalised

Officials said the gas leak took place from a pipeline that runs from the sea to the factory of a private fertiliser company. The Tamil Nadu pollution control board said the level of ammonia in the air was 2,090 microgram (mm in cubic meter) as opposed to the accepted levels of 400 microgram. In the sea, it was 49 milligrams per litre (mg/l) as against the standard of 5 mg/l, the board said in a statement.

The southern bench of the National Green Tribunal took suo motu (on its own accord) cognisance of the leak on Wednesday and directed the TNPCB to file a report to be heard on January 2.

The gas leak happened at 11.45 pm on December 26 from the fertiliser manufacturing facility of Coromandel International Limited (part of the Murugappa Group) in Ennore, said state government in a statement.

Government officials said that they were alerted at 12.45 am when gas bubbles were seen coming out of the pipeline near the shore.

Simultaneously, local residents from villages including Periakuppam and Chinnakuppam, reported a pungent odour and complained to the city police. “The unit immediately started depressurising the pipeline … and completed the operation within 20 minutes,” the statement said.

Some people received first aid due to eye irritation and breathing difficulties, officials said. Several families left their homes to escape the harmful effects of the gas leak.

Tamil Nadu health minister M Subramnaian said that more than 100 people from Ennore were affected and more than 50 hospitalised. “All of them are stable now,” he told reporters after meeting the patients.

On Wednesday, locals protested demanding that the factory be closed. “Nobody warned us about the gas leak. Suddenly last night, my children and I were all feeling equally breathless,” said a 28-year-old mother of two young children. People complained of burning in their eyes, throat, nose and chest. Some fainted and complained of breathlessness.

“We saw several dead fish from late last night,” said the president of the Kattukuppam Fishermen Cooperative, R L Srinivasan. “When the oil spill happened and fish died, it was a problem of livelihood for us. But, with this gas leak, our lives are also in danger. What is the guarantee that this will not happen again?”

The factory manufactures 400,000 tonnes of Ammonium Phosphate Potash Sulphate annually; ammonia — one of the raw materials used for manufacturing — is received from the minor port in Ennore through ships. It is transferred from there through a 2.5 km pipeline laid underneath the sea bed, which is cooled for 36 hours prior to the transfer in liquid form.

Coromandel International in a statement said that as part of their routine operation, they noticed abnormality in the ammonia unloading pipeline subsea near the shoreside and outside the plant premises. “Our standard operating procedure activated immediately, and we have isolated the ammonia system facility and brought the situation to normalcy in the shortest time,” Amir Alvi, president and head, manufacturing (fertiliser) and supply chain of the company said.

Read here: 50 hospitalised after ammonia gas leak in Chennai’s Ennore, says health minister

“During the process, few members in the local community expressed discomfort and were given medical attention immediately. All are safe and normalcy is restored. We have informed relevant authorities about the incident. Coromandel has always adhered to the highest safety standards and emergency response system.”For the people of north Chennai, the ammonia gas leak came as a second blow after they were affected by a recent oil spill. Approximately 60 people including children, who were residents of areas close to the fertiliser plant experienced unease, shortness of breath, nausea, faintness and irritation in the eyes and were treated in hospitals.