What is a risk associated with carbon monoxide when stranded in a vehicle?

Running the vehicle and heater for too long can lead to carbon monoxide poisoning because this gas is a byproduct of fuel combustion. When a vehicle operates, it emits exhaust that contains carbon monoxide, which can accumulate in enclosed or poorly ventilated spaces, such as the inside of a vehicle. If a person remains in a running vehicle with the heater on for an extended period, especially in a closed environment, they risk inhaling dangerous levels of carbon monoxide. This is particularly critical if snow or other conditions block the exhaust pipe, as it can trap the gas inside the vehicle.

Other options suggest risks associated with carbon monoxide inhalation or circumstances that are misleading. For instance, while inhalation can indeed lead to nausea, this is not the primary risk when considering the dangers of being stranded in a vehicle and running it continuously. Additionally, asserting that carbon monoxide is harmless when windows are cracked or that it only becomes dangerous if the vehicle is locked overlooks how carbon monoxide can still pose a risk in various situations, emphasizing the importance of understanding proper safety protocols when dealing with potential exposure.