Eight tenants of an apartment building on Falkland Street in west end Moncton had to be evacuated after a furnace malfunction Sunday night.
The Canadian Red Cross says a spike in carbon monoxide levels forced everyone out.
Five adults and one child were taken to hospital for examination but were later released.
Some tenants experienced nausea or headaches but no one was seriously hurt.
The Red Cross arranged for emergency accommodations and meals for several of the tenants while the furnace is repaired and the building is ventilated.