Are you aware that people annually die in the United States from carbon monoxide poisoning while recreating on or in the water near boats or personal watercraft?

Most people know of the dangers of carbon monoxide poisoning in heated structures like homes or ice fishing shelters, but I’m guessing very few realize the threat carbon monoxide poses while recreating in or on the water.

Carbon monoxide is a deadly gas that is colorless, odorless and tasteless. Because of these properties, CO poisoning often is referred to as the “silent killer.” Carbon monoxide enters the body through our lungs, where it enters our bloodstream. In the blood, it binds to red blood cells, preventing them from transporting needed oxygen throughout the body.

When exposed to high concentrations of carbon monoxide, death can occur in seconds. Continued exposure to low levels of CO over time also can lead to death.

Possible signs and symptoms of carbon monoxide poisoning include headache, nausea, confusion, vomiting, difficulty breathing, weakness and dizziness. While recreating on the water, the symptoms might be confused with being seasick, having heat stress or possibly the effects of intoxication if alcohol is being consumed. If the early warning signs and symptoms of carbon monoxide poisoning are ignored, a person might lose consciousness and succumb to the gas. Individuals exposed to CO should immediately be moved away from the source into an area having fresh air and immediately seek medical help.

Carbon monoxide is present when anything burns. The burning of fossil fuels in furnaces, heaters, cars, trucks, stoves, boat motors and personal watercraft are a few examples of where CO is produced. With proper ventilation, there generally are no issues with people getting sick from carbon monoxide. Unfortunately, there are times when the ventilation is not adequate and people die.

Any boat or personal watercraft with a running engine can result in people getting sick or dying from carbon monoxide poisoning. There are a few situations where the probability of having issues with CO while on the water increase. Everyone who recreates on the water should be aware of these situations to hopefully prevent carbon monoxide poisoning of themselves or others.

Swimming at or near the back of a running boat motor is one situation. This is especially true on boats that have a platform on the back. The platform can concentrate the boat’s exhaust. Carbon monoxide can quickly kill swimmers behind boats with running motors. Individuals should stay at least 20 feet away from the back of a boat with a running motor when swimming or when being pulled on skis, wakeboards or other devices. It is recommended that no swimming or setting on a boat’s back platform occur for at least 15 minutes after the engine is turned off.

No one should be allowed to drag in the water while holding on to the back of the boat or be seated on the back platform as the boat motors. Idling at slow speeds increases the potential for CO to accumulate at the back of a boat because the exhaust does not always dissipate. This is especially true when a tailwind is present.

Tying boats together can be dangerous when the motor of one or multiple boats is running. The exhaust from an adjacent boat can result in carbon monoxide in your boat. It is recommended that you maintain a minimum of 20 feet from another boat with a running engine or generator.

Large boats with enclosed cabins can have a problem with carbon monoxide levels, particularly if the exhaust outlet for the motor becomes blocked. Another situation might occur when operating with the front of the boat elevated and an opening to the cabin causes a backdraft, drawing exhaust inside the cabin. Owners of boats with enclosed cabins should install a battery-operated CO detector approved for marine use and frequently test it to see that it is working.

When operating a boat or personal watercraft, please make sure everyone is aware of the dangers of carbon monoxide poisoning while on or in the water and that everyone is aware of the signs of CO poisoning. If you suspect carbon monoxide poisoning, move to fresh air and seek medical help. Hopefully informing others about the potential for these problems will prevent possible tragedies.

Have a safe and enjoyable summer on the water.

Brian Blackwell is a fisheries biologist with the South Dakota Department of Game, Fish and Parks.