Is a Carbon Monoxide Detector the Same as a Smoke Detector?

Indoor Air Quality, Safety

If you are one of those people who easily get carbon monoxide detectors and smoke detectors mixed up, know that you are not alone. Many people get confused with these two detectors and it is no surprise. They are both compact, typically circular or box-type, sometimes powered by a battery, and sound an alarm to warn you about a pressing danger in your home.

Since these safety home devices have many similarities, are they basically interchangeable? Is a carbon monoxide detector the same as a smoke detector?

DP is a carbon monoxide detector the same as a smoke detector

NO. A carbon monoxide (CO) detector is NOT the same as a smoke detector. A CO detector is designed to detect carbon monoxide only, and it will sound an alarm when the amount of carbon monoxide in the air reached hazardous levels in your house. Smoke detectors, on the other hand, are designed to identify if there is a flaming or smoldering fire in the house when they sense smoke particles in its immediate area.

What are the Differences Between Carbon Monoxide Detectors and Smoke Detectors?

In reality, carbon monoxide detectors and smoke detectors have distinct differences. It is essential for homeowners to know the information about their dissimilarities so they can be protected from life-threatening situations.

How to Tell a Carbon Monoxide Detector and a Smoke Detector Apart


While both detectors alert you about the presence of dangerous gases in your home, they differ in what kind of gas they can detect that is posing an imminent risk to your life and safety.

You may have guessed that a carbon monoxide detector senses if there is carbon monoxide present in your home. When the levels of CO indoors reach a point where it is threatening to your health, it will sound an alarm, typically four beeps.

Meanwhile, smoke detectors determine if there is smoke coming from a fire in your home. Smoke may contain gases such as carbon dioxide, carbon monoxide, particulate matter (more commonly referred to as soot), aldehydes, acid gases, sulfur dioxide, nitrogen oxides, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, styrene, metals, and dioxins, at varying degrees.


Unless otherwise specified, a standard single-gas function carbon monoxide detector can only be triggered by carbon monoxide. If the carbon monoxide is lingering in your home for a few hours at 70 parts per million (ppm), it will sound an alarm. But if the carbon monoxide detector sensed 400 ppm of CO, it would be immediately triggered in a matter of minutes and go off.

On the other hand, a smoke detector is triggered by the smoke itself or its particles. The smoke alarm will be triggered depending on the specific detection and monitoring method of your detector. 

If you have an ionization smoke alarm, it contains radioactive material in the middle of electrically charged plates and so has an electrical current constantly flowing between the two plates. If smoke enters the chamber and disrupts the flow, the alarm will go off. This kind of smoke detector works better with active or flaming fires.

Smoldering fires or fires that are burning slowly are best detected by photoelectric smoke detectors. The way it works is that it points a light away from the sensor and onto its immediate environment. If the light reflects on the light sensor because of the presence of smoke, it will sound an alarm throughout your home.


Most smoke alarm designs are rounded or circular. Additionally, smoke alarms do not often bear labels on the face of the device. You might have to turn it over to see if it is indeed a smoke detector, the specific model, and the brand. 

Meanwhile, carbon monoxide detectors can come in different shapes: rounded, rectangular, or slightly oval. They are more likely to be clearly marked on the face as carbon monoxide. Some versions have a test button that sounds an audible noise of “Warning, carbon monoxide!”

Dual-purpose or hybrid alarms that detect both smoke and carbon monoxide usually have two indicator lights to warn you separately against the presence of a fire or toxic levels of carbon monoxide in your home. 


The location of carbon monoxide detectors or smoke alarms around your home may also vary because carbon monoxide and smoke behave differently. 

Smoke detectors are normally found in ceilings and or high portions of the walls. This is due to the tendency of smoke to rise, so smoke detectors are commonly situated in a more elevated place in a home. 

But carbon monoxide is slightly lighter than air. So it easily mixes with the moving air inside your home. Because of this, you don’t have to install CO detectors at any specific height. Some carbon monoxide alarms are just plugged in on electrical outlets so they can be anywhere, or connected to the home security system. 

However, authorities strongly advise carbon monoxide detectors to be installed near bedrooms and sleeping areas, and near fuel-burning appliances. 

Why Do I Need a Carbon Monoxide Detector?

Carbon monoxide is listed as one of the most deadly gases known to humankind. What makes it so much more frightening than other existing gases or chemicals is that it is odorless, colorless, and tasteless, making it impossible to trace or detect without the help of a carbon monoxide detector.

In a matter of minutes, anyone can be susceptible to carbon monoxide poisoning. What are its symptoms?

Mild CO poisoning can manifest as:

  • Headache
  • Fatigue
  • Dizziness
  • Vomiting
  • Upset stomach
  • Chest pain
  • Confusion

Severe carbon monoxide poisoning has symptoms such as: 

  • Malaise or a general feeling of discomfort
  • Shortness of breath
  • Irritability
  • Ataxia or poor muscle control
  • Altered mental status
  • Loss of consciousness
  • Coma, and 
  • Death

Carbon monoxide poisoning is preventable only with the help of a CO alarm. It is best to install CO alarms near bedrooms or places where people often assemble. You must also install them in areas where gas-powered appliances are being used. But not too close to prevent unnecessary false alarms.

Can Carbon Monoxide Detectors Detect Smoke and Fire?

You may be hoping that your CO detectors can detect the presence of smoke and fire. We hate to break it to you, but no, single-function carbon monoxide detectors DO NOT detect if there is smoke in your home or if there is a flaming fire going on.

The composition of carbon monoxide is simply one atom of carbon and one atom of oxygen. While smoke is a medley of various gases and chemicals. Although smoke has carbon monoxide in its mixture, it is not responsible to rely on a standard carbon monoxide alarm to detect a raging fire.

But hybrid or dual-purpose detectors are a different story. The carbon monoxide detector and smoke alarm combo in one device has been proven to detect both. These dual-purpose detectors have been reported to prevent the loss of life and property damage on many occasions.

Are Carbon Monoxide and Smoke Detectors Required?

The National Fire Protection Association in America has released the National Fire Alarm and Signaling Code which requires a minimum of one smoke alarm in every sleeping area, on every level of a home, and urges putting additional smoke detectors in larger houses.

How about carbon monoxide detectors?

Forty-eight US states require the installation of carbon monoxide detectors in American homes. This is mandated by the U.S. Consumer Product Safety Commission (CPSC) since 2001 which contains guidelines and information about CO and exhorts all homeowners to have at least one fully-operational carbon monoxide detector. 
Some states like Alaska require these carbon monoxide detectors to be approved by the State Fire Marshal before use. Connecticut, New Hampshire, Oregon, Pennsylvania, Rhode Island, Utah, Vermont, Washington, West Virginia, and Florida also require them in all brand-new construction, especially those with boiler units. The state of Minnesota also calls for motorboat owners to install CO detectors in their watercraft.

Leave a Comment