Chlorine leak on Mumbai Port Trust’s Sewri yard: A case study

The Mumbai Port Trust chlorine leak of July 2010 remains one of India’s clearest examples of how an abandoned chemical store becomes a public health emergency. This case study, published in the Journal of Pharmacy and Bioallied Sciences by Rakesh Kumar Sharma, Raman Chawla and Surendra Kumar, examines what happened and what it revealed about preparedness.

How the chlorine leak happened at Sewri

At around 3am on 14 July 2010, chlorine leaked from a corroding cylinder weighing about 650 kg at the Haji Bunder hazardous cargo warehouse in the Mumbai Port Trust yard at Sewri. More than 120 people in the neighbourhood were affected, including students, labourers, port workers and firefighters. Seventy were reported to be in a critical condition.

The yard sits next to a college whose hostel was barely 100 metres from the leak. Students who were asleep were worst affected and began vomiting; those who were awake and studying noticed the problem sooner. The hostels were cleared by 4am, and police vans and ambulances took people to hospital, where it took some hours for symptoms to subside. Mumbai Police registered a gas leakage case against unidentified persons.

The cylinders had been abandoned by an importer in 1997, more than a decade earlier, and the Port Trust had been unable to sell them. Officials said the leak came from one of 141 cylinders in storage. Rescue and relief teams worked for more than six hours. Fire officials, municipal corporation teams and experts from several chemical companies and the Mutual Aid Response Group were needed to identify, seal and clamp the leaking cylinders, while firefighters used water curtains to dilute the spreading gas cloud.

Why a chlorine leak spreads the way it does

Chlorine is a greenish-yellow gas at ordinary temperature and pressure, with a pungent, suffocating smell. It is about two and a half times heavier than air, which is why it settles and spreads at ground level. It reacts readily with lime and caustic soda to form hypochlorites, and solutions of both are generally used to handle leaks.

The gas is primarily a respiratory irritant and is severely irritating to the mucous membranes, the eyes and the respiratory tract. The threshold limit value is 1 ppm. At higher concentrations or longer exposures it causes restlessness, throat irritation, sneezing and heavy salivation, and in extreme cases attacks lung tissue and produces pulmonary oedema.

What the case study found

The authors describe the incident as a case of ignorance and negligence, with contraventions of safety and environmental safeguard requirements under existing statutes, and a failure to maintain the fail-safe conditions required for chlorine storage. Their analysis found significant gaps in the availability of a neutralisation mechanism, and noted that storing chlorine in the open increased the risk of cylinders bursting.

The framework meant to prevent this

Chemical emergencies involving hazardous materials are not uncommon in India. More than 25 incidents were identified in the National Disaster Management Guidelines on Chemical (Industrial) Disaster Management, released in May 2007.

The Government of India has since institutionalised an emergency preparedness framework at national, state and district level under the Disaster Management Act, 2005, intended to mitigate such incidents when preventive safety provisions fail. The Ministry of Environment and Forests has been preparing a National Action Plan on Chemical (Industrial) Disaster Management, based on those guidelines, to drive capacity development across the country.

CDPRR works on industrial chemical risk through its risk assessment and mapping services and its CBRN training modules, and has written more broadly on CBRN disaster prevention. The guidelines themselves are published by the National Disaster Management Authority.

The full paper is available at doi.org/10.4103/0975-7406.68496.

(Read the full paper in PDF format)