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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Toxicologist Dan Daggett tests a pop-up camper's propane stove for carbon dioxide emissions. Always leave a window flap open when cooking in a camper. © DHFS
Toxicologist Dan Daggett tests a pop-up camper's propane stove for carbon dioxide emissions. Always leave a window flap open when cooking in a camper.


August 2001

Senseless killer

Without any warning, campers, hunters, boaters and ice fishers die every year from carbon monoxide poisoning. We'll help you prepare to stay alive.

Daniel A. Daggett and Lynda Knobeloch

Everybody is at risk | Signs of CO poisoning
Be prepared and stay safe | Carbon monoxide facts
These don't mix

Overnight camping trips are supposed to be filled with fun and adventure. Occasionally, however, tents, campers, boats, shanties and cabins can be filled with a dangerous, silent killer. Last year alone carbon monoxide (CO) killed seven campers, hunters and boaters in Wisconsin, turning a season of outdoor fun to tragedy for affected families and friends.

The deaths resulted from five separate incidents involving small propane heaters, cabin and trailer heaters, a boat generator and a charcoal grill that liberated carbon monoxide. In all these instances, the victims were away from their homes on camping, hunting and fishing trips and died while they slept. These tragedies teach us that vacationers need to be more aware of the dangers CO can pose.

Everybody is at risk

Carbon monoxide facts
Carbon monoxide is the most common cause of fatal poisoning in Wisconsin.

Nationwide, CO is responsible for about 2,100 unintentional deaths per year.

The U. S. Consumer Product Safety Commission estimates that portable heaters, stoves and lanterns cause 30 deaths and 450 injuries to persons in tents, campers and vehicles every year.

Carbon monoxide is an odorless, colorless and tasteless gas. Any heat or energy source that burns fuels such as wood, gasoline, charcoal, propane, kerosene or diesel, produces carbon monoxide. Unvented sources, like the popular "sunflower" or catalytic heaters, charcoal grills, kerosene heaters and propane stoves are examples of CO-producing devices that require extra caution. Since these devices do not have a vent to carry CO emissions outside, they should only be used for outdoor activities. Operating unvented devices in enclosed spaces is very dangerous. It is especially dangerous to heat with an unvented device in an area where people will be sleeping. CO levels can accumulate quickly inside a tent or a cabin without warning and if you're not prepared, the results can be deadly.

Vented heat sources, such as fireplaces, woodstoves, gas stoves, water heaters and furnaces, have chimneys or vents to carry CO and other combustion products outdoors. Though these appliances are generally safe for indoor use, they can also cause CO problems. All fuel-burning appliances should be inspected annually to ensure they are operating properly and the chimneys and vents are not plugged by snow and ice, or by animal or bird nests. Annual inspections are especially important at vacation properties where furnaces and fireplaces are used less often, animals have more time to build nests, vents can get blocked without notice, and vent obstructions may be more common.

Signs of CO poisoning

Since you can't see, smell or taste carbon monoxide, you won't know that you are being exposed to it unless you have installed CO detectors. The first signs of poisoning – including headache, fatigue, dizziness, shortness of breath, nausea and mental confusion – are often mistaken for other illnesses. Symptoms of CO poisoning might also include weakness, stomach pain, diarrhea, blurred vision, chest pains and numbness. Sometimes people being poisoned by CO mistakenly think they are coming down with the flu.

These don't mix
Sources of carbon monoxide:
enclosed spaces
gas or diesel engine exhaust
houseboats or boat cabins
gas grills
charcoal grills
pick-up truck beds with caps
propane or kerosene heaters
unvented furnaces
ice fishing shanties

If somebody is experiencing these symptoms and CO might be involved, take immediate action. don't assume that everyone will have the same symptoms at the same time. Individuals who have heart disease or breathing problems may be more sensitive to CO than others. Also people often receive different levels of exposure depending on their activity and distance from the source. People with higher exposures or underlying health problems often experience symptoms earlier than others and their symptoms can be more severe.

If you suspect a CO problem, move everyone outdoors immediately. Mild symptoms of carbon monoxide poisoning usually improve within a few minutes after getting fresh air. If you experience severe symptoms, such as dizziness throbbing headache, or vomiting, you should seek emergency medical care. don't attempt to drive to an emergency room if you are feeling dizzy or sleepy – call 911 for assistance instead.

Propane and kerosene heaters are prime sources of carbon monoxide emissions. You need to have fresh air coming into the room, cabin or shanty to vent harmful emissions. © Jay Salvo
Propane and kerosene heaters are prime sources of carbon monoxide emissions. You need to have fresh air coming into the room, cabin or shanty to vent harmful emissions.

© Jay Salvo

Be prepared and stay safe

  • Use carbon monoxide detectors. Just like smoke detectors, a CO detector is easy to install and reasonably priced ($20-40). Install plug-in units in your home, vacation cottage or RV, especially in the sleeping area. Consider buying a battery-powered CO detector to take with you while vacationing. Battery-powered detectors can monitor CO levels in campers, tents, boats and cars. Be sure the batteries are fully charged and that the detectors are placed near the sleeping area, so they will wake you up if there is a problem.

  • Trust your carbon monoxide detector. If it sounds the alarm and anyone has symptoms of headache or drowsiness, leave the area immediately and call 911.
    If the alarm sounds and you have no symptoms, reset the detector. If it sounds again, you probably are being exposed to low level of carbon monoxide that can cause chronic fatigue and other illnesses. If you can identify the CO source, turn it off until it can be repaired or replaced. If you can't find the source, call the fire department or local health department for assistance.

  • Have the heating system and chimney of vacation cottages inspected at the beginning of each heating season by a professional heating contractor. Maintain your furnace and gas appliances according to the manufacturer's instructions. Consider placing animal excluders over the exhaust vent to keep birds and small mammals out.

  • Maintain the exhaust system of your car, truck or RV. A leaky muffler can allow lethal levels of carbon monoxide to seep into the passenger compartment.

  • Never idle a car engine near a tent, in a garage or in other enclosed space.

  • Never use fuel-powered space heaters, gas grills or charcoal grills in enclosed spaces. Cold weather or rain might tempt you to bring a grill or heater indoors, but never do this! It is extremely dangerous. When camping, keep grills and vehicles away from your tent so that CO won't enter the sleeping area. Never use a gas oven to heat your home.

  • Consider sending a CO detector to college or summer camp with your children. Teach them how to respond if the alarm sounds.

  • Remember the warning signs of carbon monoxide exposure – throbbing headache, drowsiness, dizziness and nausea. Teach children about the sources and signs of carbon monoxide poisoning. Tell them to call 911 if they suspect a problem.

Daniel A. Daggett and Lynda Knobeloch are toxicologists with the Wisconsin Department of Health and Family Services where they work on environmental health issues.