Carbon monoxide is an odorless, colorless gas that can build up in your home without your knowledge. A carbon monoxide leak can make you very sick and may be fatal. It’s important to know how this gas might get inside your home.

Carbon monoxide is a gas that forms when fuels such as natural gas, coal, and propane are burned but don’t burn completely. This can happen for many reasons, including improper ventilation or a problem with an appliance like a gas stove.

Symptoms of carbon monoxide poisoning

If you inhale a lot of carbon monoxide, you can pass out. If you’re sleeping or drunk, you may not realize anything is happening. You can die from breathing in too much carbon monoxide before you even know you’re having symptoms.

If you do have symptoms of carbon monoxide poisoning, they may be flu-like and may include:

  • headache
  • dizziness
  • weakness
  • upset stomach
  • vomiting
  • chest pain
  • confusion

If you have unexplained symptoms like these, leave the building and seek medical care. It’s a good idea to keep a working carbon monoxide detector in your home if you have gas appliances or fireplaces.

Carbon monoxide is produced whenever a fuel burns. Since homes are generally insulated and sealed to keep outside air from getting in, carbon monoxide can build up inside. If you breathe it in, it stops your body from getting enough oxygen and can be fatal.

Anything in your home that burns fuel, including the examples listed below, can be a source of carbon monoxide.

Appliances that burn fuel

Many household appliances can produce carbon monoxide if they malfunction or are improperly used:

  • Gas appliances: Any appliance that uses natural gas or propane can release carbon monoxide if it’s not properly vented or maintained, including:
    • stove
    • oven
    • clothes dryer
    • water heater
  • Heating systems: A heater that burns fuel (natural gas, coal, oil, or propane) can generate carbon monoxide, especially if it needs maintenance or has broken parts or blocked vents. Examples include:
    • furnace
    • boiler
    • space heater
  • Fireplaces and woodstoves: An improperly vented fireplace or woodstove or a blocked chimney can cause smoke and carbon monoxide to back up into your home. Forgetting to open your fireplace flue before using the fireplace can be very dangerous.

Other ways carbon monoxide may get inside your home

Vehicles or other equipment with a motor

Running your car, a generator, or other gas-powered equipment inside an attached garage, in a basement, or even near an open window of your home can allow carbon monoxide to get into your living space.

Gas-powered generators

People often use gas-powered generators during power outages or after natural disasters. According to the Consumer Product Safety Commission (CPSC), nearly 100 people die in the United States each year from carbon monoxide poisoning due to gas-powered generators.

Never use these generators inside your home or in an enclosed or partially enclosed area such as a garage, basement, or crawl space. Never use one outdoors too close to your home or near an open window or door. Fans will not remove carbon monoxide from an enclosed area in your home.

Charcoal grills

Using charcoal grills indoors or in a semi-enclosed space such as a garage can produce dangerous levels of carbon monoxide.

Blocked vents and flues

Snow, debris, or bird nests can block exhaust vents and force carbon monoxide back into your home.

Kerosene heaters

Kerosene heaters use a special type of cleaner-burning kerosene to produce heat. While it is legal to use them in your home if you keep them near an open window, they do produce carbon monoxide. In addition to being a fire hazard, they can be difficult to vent properly.

These heaters can be a source of carbon monoxide if used in your home or even when used outdoors if they are placed too close to open windows.

Several factors may increase the risk of carbon monoxide buildup inside your home, such as:

  • Incorrect or inadequate ventilation: It’s essential to keep any exhaust vents clear and working properly so that air can flow into and out of your home. Adequate airflow can prevent carbon monoxide from building up.
  • Nonprofessionally or incorrectly installed appliances: If you have gas appliances or replace gas appliances, always hire a licensed professional and get any required local permits for them. Incorrectly installed appliances may not vent properly.
  • Lack of routine maintenance: Fuel-burning appliances need regular maintenance. If you don’t keep up with these tasks, there’s a greater risk that one or more of these appliances may not work properly.
  • Home renovations not performed by licensed professionals: It’s important to use professionals for all home renovations. Licensed professionals know how to install new appliances correctly and how to follow local building codes that ensure your safety. Making even simple changes to your home’s ventilation system may affect how gases flow through and out of your home.

In addition to keeping your gas appliances well maintained and using licensed professionals for any changes or renovations involving heaters or other gas appliances, here are other ways to help prevent carbon monoxide in your home:

  • Keep working carbon monoxide detectors in your home and replace the batteries every year.
  • Have your heating system inspected, especially if it stops working well.
  • Never operate a gas space heater inside your garage, home, or basement or outdoors near an open window.
  • Never operate a gas-powered generator inside your home; in any enclosed area, such as a garage, basement, or crawl space; or near open windows or doors.
  • Follow all operating instructions if using a kerosene heater indoors. The CPSC notes that kerosene heaters release carbon monoxide and recommends using them only in a room with the door open, near a window that is open at least 1 inch, or both.

Carbon monoxide is an odorless, colorless, toxic gas. Breathing it in can be fatal, so it’s important to understand how this gas may get inside your home.

If you have appliances that use fuels such as natural gas, coal, or propane, it’s important to keep carbon monoxide detectors working and ensure that the appliances are in good working order.

Never operate a gas-powered generator in your home, garage, basement, or crawl space or near an open window or door to your home. If possible, avoid using a kerosene space heater indoors, but if you must, follow the instructions carefully and use it only in very well-ventilated areas.

If you have symptoms of carbon monoxide poisoning, get outside immediately and seek medical care. Carbon monoxide poisoning can cause a loss of consciousness and can be fatal.