Carbon Monoxide Safety: Alarms, Furnaces and Generators

Published September 25, 2026 · Heating, cooling and safety

Carbon monoxide alarms are vital safety devices, and knowing the symptoms of carbon monoxide poisoning can save lives. Always use portable generators safely outdoors to prevent this dangerous gas from entering your home.

What is Carbon Monoxide?

Carbon monoxide, often called CO, is a colorless, odorless gas. It is also tasteless. Because you cannot see, smell, or taste it, CO is very dangerous. It is sometimes called the “silent killer.” This gas is a byproduct of burning fuels. Common sources in a home include furnaces, gas stoves, water heaters, clothes dryers, fireplaces, and portable generators. When you breathe in CO, it replaces the oxygen in your blood. This can quickly lead to serious illness or even death.

Carbon Monoxide Alarms: Your Early Warning System

CO alarms are essential for detecting this dangerous gas before it causes harm. They work much like smoke detectors, sounding an alarm when CO is present. Proper placement and maintenance are key to their effectiveness.

Where to Install Alarms:

The U.S. Consumer Product Safety Commission (CPSC) advises installing battery-operated carbon monoxide alarms, or alarms with battery backup, on every level of your home. You should also place them outside all sleeping areas. This ensures that you and your family can hear the alarm even when asleep.

Alarm Checklist:

• Place correctly: Install an alarm on every level of your home. Put one outside each sleeping area.
• Check power: Make sure alarms are battery-operated or have a battery backup. This way they work even if the power goes out.
• Test regularly: Follow the manufacturer’s instructions for testing your alarms. Most have a test button.
• Replace batteries: Change batteries twice a year, or when the alarm chirps to signal low battery power.
• Replace alarms: Alarms do not last forever. Check the alarm’s expiration date. Replace the unit when it expires, usually every five to seven years.

Recognizing Carbon Monoxide Poisoning

Knowing the symptoms of CO poisoning is crucial. Because they can seem like the flu, people sometimes do not realize they are being poisoned. The CPSC lists several common symptoms:

• Headache
• Dizziness
• Weakness
• Nausea
• Vomiting
• Sleepiness
• Confusion

These symptoms can get worse with longer exposure. They can also affect children and pets more quickly. If you suspect carbon monoxide poisoning, the CPSC says you should get outside to fresh air immediately. Then, call 911 for emergency medical help.

Safe Use of Portable Generators

Portable generators can be very helpful during power outages. However, they produce carbon monoxide. It is extremely important to use them safely to prevent CO from entering your home.

The CPSC states you should never use a portable generator inside a home or garage. This is true even if doors and windows are open. The gas can build up quickly and reach dangerous levels. Instead, run your generator outdoors at least 20 feet from your house. Make sure the exhaust is pointed away from your home, as well as away from any windows or vents.

Generator Safety Checklist:

• Outdoor use only: Always operate generators outdoors. Never use them inside your home, garage, basement, or any enclosed space.
• Distance and direction: Place the generator at least 20 feet away from your house. Point the exhaust away from windows, doors, and vents.
• Stay dry: Never operate a generator in wet conditions. This includes rain or snow. If you must use it in damp weather, use a canopy or cover. Make sure it is open on all sides.
• Refuel safely: Turn off the generator and let it cool down before adding fuel. Hot engine parts can ignite gasoline.
• Store fuel safely: Keep fuel in approved containers. Store them in a well-ventilated area outside your home. Keep them away from heat sources.
• Use proper cords: Use heavy-duty extension cords designed for outdoor use. Make sure they can handle the power load. Plug appliances directly into the generator or use an outdoor-rated extension cord. Never plug the generator into a wall outlet. This is called backfeeding and can send power to the utility lines. This can harm utility workers or your neighbors.

Furnace and Appliance Safety

Many common household appliances burn fuel and can produce carbon monoxide if not working correctly. Keeping them in good repair and ensuring proper ventilation is important for safety.

• Professional inspections: Have a qualified professional inspect your furnace, water heater, and other fuel-burning appliances every year. This includes gas stoves and clothes dryers. They can check for proper function and safe ventilation.
• Ventilation: Make sure vents and flues for fuel-burning appliances are not blocked. Clear snow or debris from outdoor vents. A blocked flue can cause CO to back up into your home.
• Chimney cleaning: If you have a fireplace or wood-burning stove, have your chimney cleaned and inspected annually by a qualified professional. Blockages can prevent smoke and CO from escaping.
• Never use gas ovens for heat: Do not use a gas oven to heat your home. It can produce high levels of CO.

When This Advice May Not Fit

While this information helps you make good decisions about carbon monoxide safety, some situations require help from a qualified professional or emergency services.

• Suspected CO poisoning: If you or anyone in your home experiences symptoms of carbon monoxide poisoning, immediately get everyone into fresh air outdoors. Then, call 911 for emergency medical assistance.
• Gas line issues: If you smell gas or suspect a problem with a gas line, do not try to fix it yourself. Leave your home immediately and call your gas utility company or 911 from a safe location. A qualified professional should always work on gas lines.
• Appliance repair: If a fuel-burning appliance, like your furnace or water heater, is not working correctly or you suspect it is leaking CO, contact a qualified professional for repair. Do not attempt to fix it yourself.
• Structural damage: If your home has structural damage that affects ventilation or the integrity of appliance flues, consult a qualified professional. They can assess and safely repair the damage.