Passenger ferry fatality highlights risks of poor ventilation

Aerial view of Sydney Harbor and Kirribilli Peninsula in Australia. Credit: Getty

A woman has died due to suspected inhalation of toxic gases in a confined space onboard a passenger vessel operating in Sydney harbour.

Paramedics were unable to revive Shalina Abdulhussein after she was accidentally locked in the toilet cubicle of the All Occasion Cruises-operated, three-level catamaran Lady Rose on February 2.

The tragic incident has highlighted the dire consequences of hydrogen sulphide escaping from poorly maintained onboard sewage systems. Hydrogen sulphide is a gas produced during the decomposition of waste. According to the Occupational Safety and Health Administration (OSHA), in modest concentrations of between 700 and 1000ppm it is toxic, and can lead to sudden collapse and death.

While the cause of death is yet to be officially confirmed, a New South Wales Police-issued report has stated that several gas detection tests conducted in a bathroom area of the vessel were found to be in excess of safe operating levels. Specifically, HAZMAT crews confirmed the detection of hazardous levels of hydrogen sulphide gas.

In the wake of the fatality, the managing director of ACO Marine, a company that supplies wastewater treatment systems, has issued a recommendation to all passenger ferry operators to ensure that all bathrooms and toilet cubicles are fitted with sensors as one simple method to better detect dangerous levels of hazardous gases generated from untreated effluent.

Mark Beavis’ recommendation said, “Sensors with integrated alarms on the bridge would allow for more immediate action in the event of any hazardous gas leaks and the integrity of the seal between the cabin space and the wastewater holding tank should be checked regularly. No doubt the enquiry will throw more light on the cause and effect of this case and whilst a biological treatment system would not be a practical solution for a day boat, better wastewater management practices are clearly required.”

Beavis added that the incident has served to highlight the issues of poorly maintained chemical toilers and poor, or obstructed, ventilation in small toilet cubicle spaces. “Some small passenger vessels do not have installed treatment systems and therefore store wastewater in holding tanks, but if these are not regularly flushed and aerated then the contents can become anaerobic and generate lethal H2S gas,” he explained.

Investigations into the incident by the Australian Maritime Safety Authority and New South Wales Police continue.