Best Low Level Carbon Monoxide Detector (Most Sensitive)

Carbon Monoxide Detector, CO Detector, Low Level CO Detector -

Best Low Level Carbon Monoxide Detector (Most Sensitive)

Carbon monoxide (CO) is a deadly gas and can even become a health risk at low levels. Low level carbon monoxide detectors alarm occupants at 25 ppm, compared to generic CO alarms that trigger at 70 ppm after 60 minutes. Obtaining a quick-alarming carbon monoxide detector offers health benefits, especially for the elderly, pregnant, and those with pre-conditions.



  • Low level carbon monoxide detectors provide early warning for low ppm CO exposure.
  • Low level CO alarms are more affordable.
  • A plethora of low level carbon monoxide detectors are available.
  • Alarm at 25 ppm after 60 seconds.
  • Carbon monoxide symptoms may be confused as "flu-like"
  • It can be difficult to track down the carbon monoxide source.
  • Carbon monoxide poisoning public awareness is still limited.
  • Carbon monoxide is a silent killer.

What Is Considered a Low Level of Carbon Monoxide?

Anything less than 50 ppm is typically considered as a low level of carbon monoxide. Depending on who you ask, this definition may vary. Although it is termed "low level," these CO concentrations can still be dangerous.

According to the Cleveland Clinic, the symptoms of low levels of CO exposure include:

  • Mild headache
  • Mild nausea
  • Shortness of breath

What Is a Low Level CO Detector?

A low level carbon monoxide detector is a special analyzer that alarms at lower concentrations than a generic CO detector.

A typical CO detector alarms at 70 ppm after 60 minutes. The Forensics Detectors low level carbon monoxide detector will alarm at 25 ppm after 60 seconds.

Who Needs a Low Level CO Detector?

Early and low level alarming offers added protection for everyone. However, certain groups are more sensitive to the adverse health effects of carbon monoxide. These groups include seniors, the elderly, pregnant women, young children, and those with medical conditions.

The Mayo Clinic reports that seniors can develop brain damage more easily, and those with breathing problems or anemia are more likely to get sick when exposed to CO.

Carbon monoxide is very dangerous for young, developing brains, especially for unborn babies. According to a study by Miriam Delomenie, “ ...exposure during pregnancy can cause severe damage, including intrauterine hypoxia, serious neurological damage, and even fetal death.”

What Is the Difference Between a Low Level CO Detector and Normal CO Detector?

A typical carbon monoxide detector purchased from Costco or Home Depot is not a low level carbon monoxide detector. These CO alarms comply with UL2034 and are not designed to comply with OSHA CO exposure specifications. 

For example, the FORENSICS low level CO detector triggers an audible alarm when CO levels over 25 ppm are detected. Such low-level CO alarming is closer to recommend exposure limits.

Low Level Carbon Monoxide Detector

Is a Low Level CO Detector a Replacement for a Generic CO Detector?

No, it is not. 

A low level CO detector is not a replacement for a generic UL2034 CO detector. Generic carbon monoxide alarms are often mandatory in most homes.

Are Low Level CO Detectors Compliant with UL2034?

Low level CO detectors are not UL2034 compliant. This is because they do not meet the UL2034 alarm trigger points, which are set at a higher level (70ppm) compared to low level CO detectors (25ppm for the Forensics Detectors Low Level CO Detectors). Although low level CO detectors alarm faster, they also increase the likelihood of false positive alarms, which could put a strain on local fire departments.

UL2034 has high alarm points, which are higher than recommended exposure limits set by WHO, OSHA, NIOSH, and ACGIH. While it may seem strange, this is a necessary balance to ensure both carbon monoxide exposure safety and the preservation of emergency services and fire department resources.

If you are looking for an extra layer of protection, it is recommended to have both a low level CO detector for faster alarming and a UL2034 compliant detector to meet local code requirements. Failure to do so may result in non-compliance as a homeowner, tenant, or landlord.

What Is the Best Low Level Carbon Monoxide Detector?

There are various low level carbon monoxide detectors on the market. The top brands and most popular products are listed below:

Do Low Level Carbon Monoxide Detectors Detect Low Levels?

Yes, they do.

They detect and alarm at lower carbon monoxide levels than a typical CO alarm. A typical CO detector alarms at 70 ppm after 60 minutes. A low level carbon monoxide detector will alarm at 25 ppm after 60 seconds.

Will a Low Level CO Detector Alarm Faster Than a Normal CO Detector?

Yes it will.

Typically, a low level carbon monoxide detector is programmed to alarm much faster than a generic CO analyzer. For example, an ordinary CO detector alarms at 70 ppm after 60 minutes. On the other hand, a low level carbon monoxide detector will alarm at 25 ppm after 60 seconds.

Do I Need a Carbon Monoxide Detector?


At the minimum, you need a basic, affordable CO detector that complies with UL2034. 

Generic CO alarms are mandatory in most homes. Check with your local city code and state legislation. The majority of US states have now mandated CO detectors. 

Which Carbon Monoxide Concentration Levels Are Important? 

No standards for CO have been decided for the air within your home. It can get confusing since various agencies, departments, and organizations have different recommended exposure levels.

However, there are some guidelines that can be extrapolated for personal safety. Below is a table that summarizes the carbon monoxide exposure recommendations by various organizations:



World Health Organization (WHO)

9 ppm average over 8 hours

Environmental Protection Agency (EPA)

The Clean Air Act requires EPA to set national ambient air quality standards (NAAQS)

9 ppm average over 8 hours

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)

9 ppm average over 24 hours

National Institute for Occupational Safety and Health (NIOSH)

35 ppm average over 10 hours

200 ppm ceiling value

Occupational Safety and Health Administration (OSHA)

50 ppm average over 8 hours

American Conference of Governmental Industrial Hygienists (ACGIH)

25 ppm average over 8 hours

CO Detector Alarming Protocol
UL2034 (USA)

> 70 ppm (60 to 240 minutes)

> 200 ppm (10 to 50 minutes)

> 400 ppm (4 to 15 minutes)

CO Detector Alarming Protocol
EN 50291:2001 (Europe)

> 50 ppm (60 to 90 minutes)
> 100 ppm (10 to 40 minutes)
> 300 ppm (3 minutes)

Forensics Low Level Carbon Monoxide Detector

> 25 ppm (1 minute)

How Sensitive Is a Carbon Monoxide Alarm?

Generic CO detectors purchased from a store alarm at 70 ppm. Low level CO detectors alarm at 25 ppm (Forensics Detectors).

When Do CO Detectors Alarm?

Nearly all carbon monoxide detectors mandated by city, county, or state jurisdictions must comply with UL2034 specifications. Nearly all CO detectors sold at Home Depot, Lowes, Costco and other large retail stores are UL2034-compliant.

The UL2034 standard requires CO detectors to alarm at certain times and CO concentrations. For example, a typical UL2034 carbon monoxide detector will follow this alarming protocol:

  • > 70 ppm for 60 to 240 minutes

  • > 200 ppm for 10 to 50 minutes

  • > 400 ppm for 4 to 15 minutes

Do CO Alarms Protect from Recommend OSHA Exposure Limits?

No, they do not. A normal UL2034-compliant CO detector has the following warning:

Warning: This product is intended for use in ordinary indoor locations of family living units. It is not designed to measure compliance with Occupational Safety and Health Administration (OSHA) commercial or industrial standards. Individuals with medical problems may consider using warning devices which provide audible and visual warnings for carbon monoxide concentrations under 30 ppm.

Low Level Carbon Monoxide Detector

osha carbon monoxide

Should I Bring My Low Level Carbon Monoxide Detector When Traveling?

Yes you should. Having a working carbon monoxide detector or a travel CO detector is a wise choice when traveling. Cars and planes can both leak carbon monoxide into the cabin. Some hotels may have CO detectors installed while others may not. Even those with installed detectors may have dead batteries or be past their expiration date. To be on the safe side, always travel with a tested CO detector to catch any problems.

Each year, there are many incidents hotel evacuations due to carbon monoxide. Leaks typically arise from large BTU appliances, such as a pool heater or a large boiler. Be safe when traveling and keep a CO detector with you. 

Low Level Carbon Monoxide Detector

What Is the Difference Between CO and CO2 Detectors?

Carbon monoxide detectors do not measure carbon dioxide gas and carbon dioxide monitors do not detect carbon monoxide gas. CO and CO2 are completely different gases and require specific detectors.

Should a Carbon Monoxide Detector Read Zero?

Yes, it should read zero in the fresh air. When a CO detector reads zero, it means there is no carbon monoxide being detected. However, a zero reading is not always representative of the surrounding environment. For example, the Kiddie Carbon Monoxide Detector has a minimum reading of 30 ppm. So any carbon monoxide levels below 30 ppm will show up as 0 ppm. 

How Do You Test a Low Level Carbon Monoxide Detector?

To test your carbon monoxide detector, see: "How do I test my Carbon Monoxide Detector?"

To summarize, there are three ways:

  • Spray carbon monoxide test gas, or bump gas, onto the detector.
  • Try the wood stick method. It is easy to try at home with no special equipment. See here.
  • Press the TEST button on your CO detector following your instruction manual.

Are Low Level CO Detectors More Expensive than Normal CO Detectors?

Yes, they are. Low level CO detectors are made up of the same components, including an electrochemical CO sensor, electronics, and display hardware. However, the software algorithms are different. Because of lower production quantities, these specialized detectors tend to be more expensive than generic carbon monoxide alarms manufactured in mass quantities. 

Why Are CO Detectors Not Made to Also Alarm at Lower Levels?

The majority of CO detectors are not low level detectors. Generic UL2034 carbon monoxide detectors are designed and programmed to alarm to prevent death. The challenge is to balance safety with false alarms that may overwhelm first responders and local fire departments.

Who Needs a Low Level Carbon Monoxide Detector?

Early and low level alarming provides added protection to seniors, the elderly, pregnant women, young children, and those with medical conditions. These groups may be more vulnerable to the adverse health effects of carbon monoxide.

      For more information on where to place CO detectors and more advanced instructions, see our blog article here.

      Final Words

      A low level carbon monoxide detector is a wise supplement to ensure protection at low CO concentrations that can trigger health problems. Low level CO detectors are now available for less than $100. Obtaining a sensitive carbon monoxide analyzer offers health benefits, especially for the elderly and those with pre-conditions.

      About The Author

      Dr. Koz is the President of FORENSICS DETECTORS where the company operates from the scenic Palos Verdes Peninsula in Los Angeles, California. He is a subject matter expert on gas sensor technology, gas detectors, gas meters, and gas analyzers. He has been designing, building, manufacturing, and testing toxic gas detection systems for over 20 years.

      gas detector expert

      Every day is a blessing for Dr. Koz. He loves to help customers solve their unique problems. Dr. Koz also loves spending time with his wife and his three children going to the beach, grilling burgers and having a cold beer. 

      Read more about Forensics Detectors here.

      Phone: +1 424-341-3886