Sauna and Carbon Monoxide: Understanding the Risk

Sauna and Carbon Monoxide: Understanding the Risk

Carbon monoxide is odorless, colorless, and lethal at high concentrations. When people hear about sauna-related deaths, carbon monoxide poisoning is one of the causes that comes up. But the risk isn't equal across all sauna types, and understanding the difference could save your life.

Which Saunas Have Carbon Monoxide Risk

Let's be clear about this upfront: electric saunas and infrared saunas produce zero carbon monoxide. There's no combustion happening, so there's no CO. If your sauna runs on electricity, carbon monoxide is not a concern.

The risk exists only with wood-burning saunas and gas-fired saunas - any heater that burns fuel. When wood or gas burns, it produces carbon monoxide as a byproduct. In a properly installed and maintained setup, all those combustion gases go up the chimney and outside. The problem starts when something prevents that from happening.

How Carbon Monoxide Gets Into the Sauna Room

In a wood-burning sauna, the firebox should be completely sealed from the sauna room. The fire burns inside a closed metal chamber, heats the sauna stones on top, and all smoke and gases exit through the chimney flue.

CO can leak into the sauna room when:

• The chimney is blocked or poorly drafting. Bird nests, creosote buildup, structural damage, or a closed damper can prevent gases from escaping, forcing them back into the room.
• The firebox has cracks or gaps. Over time, metal expands and contracts with heating cycles. Welds can crack, and gaskets can deteriorate, creating paths for CO to seep through.
• The heater was installed incorrectly. DIY installations without proper chimney connections or with inadequate flue sizing are the most common cause of CO problems.
• Burning fuel inside the sauna room. Some people bring portable gas heaters or charcoal into a sauna. This is extremely dangerous and has caused fatalities.

Symptoms of Carbon Monoxide Exposure

CO symptoms overlap with normal sauna effects, which makes them tricky to identify:

• Early symptoms: Headache, dizziness, nausea, fatigue - all of which can also happen from dehydration or staying in the sauna too long
• Moderate exposure: Confusion, impaired judgment, rapid heart rate, difficulty breathing
• Severe exposure: Loss of consciousness, seizures, death

The dangerous part is that moderate CO exposure impairs your judgment, making it harder to realize something is wrong and take action. In a sauna where you're already hot and relaxed, you might attribute early symptoms to the heat rather than a gas leak.

How to Protect Yourself

Install a Carbon Monoxide Detector

If you have a wood-burning or gas-fired sauna, install a CO detector near the sauna entrance. Standard household CO detectors work, but place them outside the sauna room (the extreme heat inside will damage the detector). Mount one in the changing room or just outside the sauna door.

Maintain Your Chimney

Have your chimney inspected and cleaned annually if you use a wood-burning sauna heater. Creosote buildup narrows the flue and can eventually block it. A chimney sweep takes about an hour and costs less than a trip to the emergency room.

Inspect the Firebox Regularly

Check your heater's firebox for cracks, rust-through spots, and deteriorating gaskets at least once a year. Look for discoloration on the exterior of the heater that might indicate hot spots or leaks. If the firebox is compromised, replace it before using the sauna again.

Ensure Proper Ventilation

Even with a perfectly sealed firebox, adequate ventilation is a safety net. Fresh air intake near the floor and exhaust venting higher up keeps air circulating. This dilutes any trace amounts of CO that might enter the room and provides the oxygen your body needs during the session.

Never Burn Fuel Inside the Sauna Room

No portable gas heaters. No charcoal. No camp stoves. No candles in enclosed spaces without proper ventilation. This sounds obvious, but improvised heating solutions in saunas have killed people.

Electric Saunas: The Zero-Risk Option

If carbon monoxide concerns you, an electric sauna eliminates the risk entirely. Modern electric heaters are efficient, easy to maintain, and produce clean heat with zero combustion byproducts. You lose the wood-burning ambiance, but you gain peace of mind.

For those who want the traditional wood-fired experience, just treat it like you would a wood-burning fireplace in your home: annual inspections, proper installation, and a CO detector nearby.

The Bottom Line

Carbon monoxide risk in saunas is limited to wood-burning and gas-fired heaters. Electric and infrared saunas have zero risk. If you use a combustion-based heater, install a CO detector outside the sauna room, maintain your chimney annually, inspect the firebox for cracks, and never burn anything inside the sauna room that isn't in a properly vented firebox. These precautions make wood-burning saunas just as safe as electric ones.