In brief
On November 6 2026, ten construction staff in Hakodate City, Japan, were taken to hospital after developing headaches and nausea during interior demolition work. Local fire officials believe a high‑pressure washer powered by an internal‑combustion engine may have emitted carbon monoxide, and investigations are underway. The incident remains under review, with further test results expected to clarify the exact cause.
On Friday morning, 10 workers were transported to hospital after reporting headaches and nausea at a demolition site in Hakodate City, Hokkaido. The workers, ranging in age from teenagers to those in their sixties, had all been carrying out interior work when the symptoms began. They were still conscious but some required assistance to move and were immediately taken to the nearest medical facility based on a 9:05 a.m. emergency call to the Hakodate Fire Department.
The fire department stated that all affected personnel were conscious, but some “were unable to move without assistance.” Symptoms described included headaches and nausea, common indicators of carbon‑monoxide exposure. Officials said no severe respiratory distress or loss of consciousness had been reported at the time of the ambulance response.
Investigators are focusing on an engine‑powered high‑pressure washer that was operating on the site. The fire department suspects the device may have emitted carbon monoxide during use. The washing equipment’s engine, typical of internal‑combustion types, is known to produce hazardous gases under certain conditions if its exhaust is not properly vented.
Local authorities have begun examining the site for other possible sources of toxic gases, such as portable power generators or exhaust stacks from construction machinery. The fire department has requested specialists in industrial hygiene to conduct on‑site analyses to determine the concentration of carbon monoxide present during the workers’ exposure.
No deaths have been reported as of the latest statements, and all 10 patients are currently stable. The local medical centers have secured beds for the workers to monitor for delayed symptoms. Hospital staff will continue to observe the patients for any changes in condition.
In a brief briefing, the chief of the Hakodate Fire Department explained that the investigation is still in preliminary stages. “We have identified a potential source,” he said, “but we are awaiting further evidence before we rule out other causes.” The department also noted that the workers were not wearing any protective breathing equipment at the time of the incident, a detail that may be significant in determining the extent of exposure.
The incident has garnered attention from regional news outlets, with the Xinhua News Agency publishing a short report that echoes the fire department’s findings. The Agency emphasized that the investigation is ongoing and that the fire department is “investigating the cause” after suspecting possible carbon‑monoxide poisoning.
Meanwhile, the company overseeing the demolition project released a statement confirming that emergency protocols had been followed and the workers were removed from the site promptly. Details about whether the company had conducted routine inspections of its equipment or enforced use of personal protective gear were not disclosed in that statement.
Given the reliance on combustion‑powered equipment in many demolition projects across northern Japan, safety officials have used the incident to remind workers of the importance of adequate ventilation and protective breathing devices. They also highlighted that high‑pressure washers and similar appliances can become hazardous if idle part of a workday, especially in confined spaces.
At present, the exact degree of carbon‑monoxide exposure remains undetermined. Investigators have not yet released quantitative measurements of the gas levels on the site, nor have they confirmed if the high‑pressure washer itself was the sole source. The workers’ medical histories, as well as the site’s ventilation conditions, have not yet been fully disclosed in official documents.
While the fire department’s early assessment points toward a combustion‑related incident, the final determination will come once all analytical data are compiled. If further testing confirms elevated carbon‑monoxide concentrations, regulatory bodies may review safety protocols for demolition works in the region.
Uncertainties remain regarding the exact mechanism of exposure, the adequacy of ventilatory measures at the site, the completion status of toxicological tests, and whether additional workers were at risk during the event. Details of the investigation’s next steps, including the timeline for any definitive conclusions, have yet to be announced by the local authorities.
