Small amounts are not usually harmful, but poisoning occurs if levels of CO in the blood become too high.
The CDC estimates that approximately 400 people die from unintentional CO exposure in the United States every year. Data specific to Minnesota show that an average of 14 people die due to unintentional CO poisoning each year. The same data shows that another 307 people visit emergency department each year for treatment of symptoms linked to unintentional CO exposure.
Smoke from fires commonly contains CO, particularly when combustion of fuels is incomplete.
If improperly vented, automobiles, furnaces, hot water heaters, gas heaters, kerosene heaters, and stoves (including wood stoves and stoves with charcoal briquettes) can cause CO poisoning. Inhaling tobacco smoke produces CO in the blood, but usually not enough to result in symptoms of
poisoning. CO disappears from the blood after several hours.
Carbon Monoxide Poisoning