Elevated Carbon Monoxide From Faulty Boilers Forces Evacuation of 20 in Claremont

Twenty people were evacuated from the Union Block Apartments at 1 Pleasant Street in Claremont after firefighters detected elevated carbon monoxide (CO) throughout the building, the Claremont Fire Department reported. Crews responded to a report of smoke in the downtown apartment complex around 10 a.m., located the source in the building’s mechanical room, and found boilers that were not functioning properly.

The department ordered an immediate evacuation after measuring high CO levels, and all 20 occupants safely left the building, the release said. Firefighters shut down the boilers in the mechanical room and asked building maintenance to resolve the malfunction, the release added. The Community Center van was available to transport those who needed a safe, warm location while crews worked.

Claremont Police, Golden Cross Ambulance, and members of the Claremont Parks and Recreation Department were on scene to assist the fire department during the response. Pleasant Street and part of Sullivan Street were closed while crews ventilated the building and ensured public safety. Occupants were kept warm on site as firefighters opened windows and used ventilation procedures to clear the apartments.

Firefighters reported that after about two hours of ventilation, carbon monoxide readings had fallen to near zero; occupants were allowed to return to their rooms at approximately 12:10 p.m., ABC22/FOX44 reported. No injuries or hospital transports were reported by emergency personnel on scene, and officials said everyone evacuated safely.

The department’s release described the sequence of actions that ended the immediate threat: identify the smoke source in the mechanical room, shut down the malfunctioning boilers, detect elevated CO levels during the safety assessment, ventilate the structure, and permit re-entry once readings returned to safe levels. The release also noted that building maintenance was asked to carry out repairs to the boiler system before it would be placed back in service.

The incident highlights prescribed safety requirements for multiunit housing in New Hampshire. Detectors and alarms are required in multi-unit dwellings and rental units under New Hampshire State Law RSA 153:10, and health authorities caution residents about carbon monoxide risks. As noted by health sources cited in the department release, “Carbon monoxide is odorless and colorless, and early symptoms of exposure include headache, dizziness, weakness, nausea, confusion and vision problems,” and carbon monoxide “can cause illness or death by replacing oxygen in red blood cells,” according to the National Library of Medicine and the Mayo Clinic.

City officials and building management were asked to confirm the repair timeline for the boilers and the status of CO detectors in the Union Block Apartments; the fire department release directs building maintenance to resolve the mechanical issue before boilers are returned to service.