Three people complained of dizziness and headache at a cannery early one morning. Suspecting possible carbon monoxide (CO) poisoning, the operator alerted the emergency services. The on-duty workers evacuated the gutting room at 10:30 a.m. The building was ventilated, and the gas company shut off the main gas supply valve to the cannery. CO measurements taken by firefighters at around 11:00 a.m. and then by the combustion-equipment contractor in the afternoon (7–10 ppm) did not exceed the regulatory threshold values. The contractor inspected the dryer burner, which is supplied with mains gas and uses the ambient air from the workshop to distribute heat from combustion of the gas in the dryer tunnel. The level of 8 ppm was within the burner’s normal operating range. No mechanical faults were found on the burner. No CO leaks were found.

The firefighters, paramedics and hospital found no evidence of CO poisoning in the three people taken to hospital. The emergency services tested five other people (two of whom did not work in that plant) because their carbon monoxide levels were between 2 and 15%. They were placed on oxygen but as their medical tests revealed no problems, they were not taken to hospital. Despite these encouraging results, the workers who were in good health were not allowed to resume work until 12:45 p.m. on Monday 26 February.

A total of 3.4 t of unprocessed sardines left in the workshop and on the line were disposed of in a NHIW skip whilst all the workers present underwent medical examinations.

The lack of a readily available CO detector meant that it was not immediately possible to eliminate any risk of workers actually being poisoned at the time when the three people complained of feeling ill. On that same day, the operator purchased a CO meter and installed it in the room to reassure workers whenever the dryer is activated.