Carbon monoxide vs. carbon dioxide

What’s the difference between carbon monoxide (CO) and carbon dioxide (CO2)? The names are very similar and they are both colorless and odorless gases, but there’s some critical differences.

Carbon monoxide is the result of an improperly ventilated fuel-burning appliance, such as an oil or gas furnace, gas hot water heater, gas oven, gas or kerosene space heater, fireplace or woodstove. In autos, CO is generated by a gasoline engine that does not use a catalytic converter. CO poisoning is the most common type of fatal poisoning.

Symptoms of CO poisoning include headaches, dizziness, nausea, vomiting, fatigue and soon unconsciousness or death. It is sometimes mistaken for food poisoning. You need to be especially alert to these symptoms in the event of power outages when people turn to generators that may be improperly ventilated or too close to a window. Cars left running in closed garages can also be deadly.

Carbon dioxide, on the other hand, occurs naturally in the atmosphere and is required for plant life. It is a natural byproduct of human and animal respiration. We breathe in oxygen and breath out carbon dioxide. CO2 is generated by gasoline engines that do have catalytic converters. CO2 poisoning is very rare and usually appears as “the bends” if you come up from a deep water dive too quickly.