Unusual ‘Chlorine’ Incident in Rhode Island

A local TV station in Pawtucket, RI published a report yesterday about a chlorine gas incident at a residential building. It seems that a contractor was emptying a sewage (septic?) tank at the building, and during the process added ‘chlorine tablets’ (sodium hypochlorite, pool chlorine tablets probably) to the tank as part of some sort of disinfection process. An unusually high number of tablets were apparently used, and two residents were taken to the hospital for treatment for breathing problems because of chlorine gas exposure.

Sodium hypochlorite when dissolved in water produces ‘bleach’. Bleach is very reactive with a number of different chemicals and frequently releases chlorine gas as part of many of those reactions. Chlorine is detectable by smell at very low concentrations, and I would suspect that there should not have been enough chlorine gas released into the building to be a serious health hazard for healthy individuals. Unfortunately, any number of pre-existing diseases could make people susceptible to breathing problems with even very low concentrations of chlorine gas.

Interestingly, this incident probably triggers a requirement to report the incident to the CSB. We certainly had a chemical release (chlorine gas) which caused serious injuries (2 hospital admissions). This was not a transportation related event, so the incident occurred at a ‘fixed site’. Since the contractor doing the work routinely handles the ‘chlorine tablets’ for the chemical treatment of sewage tanks, they would be expected to be aware of chemical hazards involved and should know about the CSB reporting requirements. I do not expect that the CSB will be sending an investigation team to an incident like this, even if they were fully staffed and not three years behind on completing accident investigation reports. But the incident still falls within the regulatory reporting requirements.