All workers suffered from carbon monoxide poisoning during dishwashing work in a hotel kitchen

Three workers started dishwashing work at 8:30 a.m. As the amount of dishes was several times greater than that on a usual day due to the large banquet held on the previous day, a total of eleven workers including eight supporting workers were carrying out dishwashing work in the kitchen from 1:00 p.m.

The procedures taken in the dishwashing work consisted of:

1. Pre-rinsing the dirty dishes by hand in a water tank.

2. Washing the pre-rinsed dishes in the automatic dishwasher.

3. Draining the washed dishes, and placing them in cupboards.

Starting around 2:00 p.m., however, workers began complaining of such symptoms as headaches and dizziness one after another. As all workers showed the same symptoms by the time they stopped work around 2:30 p.m., two seriously affected workers were taken to the hospital by ambulance and the other nine workers were also taken to the hospital by microbus for treatment. All the workers were diagnosed as suffering from carbon monoxide poisoning.

Although two systems were installed in the kitchen as ventilation facilities - a suction type hood (two units) for the kitchen and a local ventilator for the gas water heater - neither of these systems was in operation. Only two fans attached to the ceiling above the automatic dishwashing machine were being used at the time.

1.Carbon monoxide gas generated by incomplete combustion in the gas water heater gradually accumulated.

2. Ventilation was insufficient, and the following can be cited as the causes for such insufficient ventilation.

(1) The room was closed to outside air as the windows were shut because of rain, and the two fans that were in operation simply circulated the polluted air.

(2) The local ventilator to discharge gas such as carbon monoxide gas generated by the gas water heater was not in operation.

(3) The exhaust ventilator for the kitchen was not in operation either.

3. Work supervision was not conducted. In particular, the eleven workers were odd-jobbers. As a majority of these workers were part-timers, they did not know how to operate the ventilation facilities.