CO2 Monitor for Indoors and Schools (updated for 2024)

Carbon Dioxide Meter, Carbon Dioxide Monitor, CO2 Meter, CO2 Monitor -

CO2 Monitor for Indoors and Schools (updated for 2024)

Gas detection plays a crucial role in ensuring children's safety in classrooms by monitoring carbon dioxide levels. Maintaining CO2 concentrations below 1000 ppm, achievable through the use of CO2 monitors, is essential for a healthy learning environment. The significance of CO2 detection has increased due to its direct correlation with the presence of airborne pathogens. Fortunately, the COVID-19 pandemic has heightened awareness about indoor air quality in schools, prompting school districts to proactively enhance ventilation and implement carbon dioxide surveillance measures. By prioritizing gas detection and monitoring, educational institutions can effectively mitigate the risk of airborne pathogen transmission and safeguard the well-being of students.



  • Carbon dioxide gas gives a good indication of air quality and virus infection risk.
  • CO2 public awareness has increased now mandating CO2. monitoring in schools.
  • Digital CO2 monitors are cheap, accessible, and easy to use.
  • CO2 levels should be kept below 1100 ppm. 
  • Some states and school districts are slow to adopt CO2 monitoring. 
  • Carbon dioxide was not seen as a serious threat but research shows can reduce student focus.

The Best CO2 Monitor for Indoors?

The best CO2 monitor for a school or classroom is the Forensics Detectors CO2 monitor. It alarms at the AB841 standard level which is 1100ppm and also available in USB power or wall mount 110V power options.

What Should the CO2 Level Be In a Classroom?

The CO2 level in the classroom should be close to the outdoor CO2 level, which is about 413 ppm. However, achieving this means leaving all doors and windows open for air exchange, which is not always practical.

Indoor CO2 levels below 1100ppm are considered acceptable.

What Is the CO2 Level In the Outdoors?

You may have heard that the outdoor CO2 level has slowly been creeping up due to global warming. In 2021, the amount of carbon dioxide in the atmosphere was about 413 ppm. In other words, the air surrounding us is roughly 0.0413% CO2.

How Does CO2 Build Up In the Classroom?

As students exhale, carbon dioxide accumulates in the classroom. With time, the CO2 level starts to increase beyond the nominal 413 ppm.

The amount of carbon dioxide indoors can be well over 1000 ppm and can even approach 3000 ppm. The absolute CO2 level reached depends on the classroom's ventilation, fresh air intake, number of students, and volume.

A high CO2 concentration is generally unsafe as it has debilitating effects on students.

How Does CO2 Relate to Airborne Virus Infection?

Along with exhaling CO2, students spray out micro droplets when talking, singing, or breathing. For sick students, these dispersed particles may contain pathogens that can remain suspended in the air for hours. 

As we exhale more and more, CO2 levels and airborne virus concentrations begin to rise within our surrounding environment.

How Can CO2 Be Reduced In the Classroom?

The CO2 levels can be reduced by controlling three key variables:

  • Ventilation. The ventilation system controls the air change rate, or how much fresh air is getting into the classroom.
  • Classroom volume. The larger the classroom, the longer it will take for CO2 levels to increase due to dilution effects.
  • Student count. More students in the classroom leads to more carbon dioxide being exhaled and greater CO2 levels.

In the post-pandemic world, it is common to see schools upgrade ventilation systems, control student count, and hold classes in larger spaces.

What About Air Sterilization to Kill Airborne Pathogens?

Yes, air sterilization is a legitimate approach to disinfect airborne pathogens in the classroom. 

One commonly used approach is ultraviolet light, which zaps the virus and kills it in the air. The YouTube clip below explains more. 

Has the Link Between CO2 Levels and Virus Infection Risk Been Scientifically Proven?

Yes it has. This relationship has been shown by research from the University of ColoradoHarvard School of Public Health, and MIT researchers.

The Technical University of Berlin showed that increasing uncontaminated air reduces indoor concentrations of CO2 and other aerosols. In turn, this strategy of fresh air ventilation lowers one's infection risk.

After considerable research effort, academics have concluded that keeping CO2 levels as low as possible will help reduce infection risk. Aerosol monitoring is an important first step, as seen by many school districts across the world adopting CO2 monitoring in the classroom.

How Do You Measure CO2 Levels In a Classroom?

Carbon dioxide is measured through a carbon dioxide monitor. This device has a sensor cell and works by detecting CO2 molecules via infrared light.

The infrared light is absorbed by CO2 molecules, an effect similar to the greenhouse gas effect warming up the Earth. Due to the light absorption from the CO2 molecules, this change can be detected electrically. A photodetector detects the decrease in infrared light received and the output signal is proportional to the CO2 gas concentration. 

Do Classrooms Require CO2 Monitors?

Monitor requirements depend on your state, city, and county. For example, Californian classrooms are now required to have a carbon dioxide monitor to track proper ventilation. This also ensures minimum risk in virus distribution, inhalation, and contraction.

In 2021, the California legislature passed AB841AB-841, requiring all classrooms to monitor CO2 levels.

What Are the Requirements for CO2 Monitors In Californian Classrooms?

  • AB841 mandates that CO2 monitors must be mounted to the wall between three and six feet above the floor and at least five feet away from the door and operable windows.

  • The monitor must display the carbon dioxide readings to the teacher through a display on the device.

  • The monitor must provide a notification through a visual indicator or other alert system when the carbon dioxide levels in the classroom exceed 1100 ppm.

  • The monitor must maintain a record of previous data, including the maximum carbon dioxide concentration measured.

  • The monitor must have a range between 400 ppm and 2000 ppm.

  • The monitor must be certified by the manufacturer to be accurate within 75 ppm at 1,000 ppm of carbon dioxide. The device must also function properly with calibration every five years or more.

What Is the Recommended Indoor CO2 Level?

We have collected a few interesting recommended indoor CO2 levels. These include the following:

  • The California State legislature passed AB841 that requires classrooms to monitor CO2 and alarm at 1100 ppm.
  • Washington State requires CO2 monitoring in restaurants and for the monitor to alarm at 450 ppm.
  • The American Society of Heating, Refrigerating, and Air-Conditioning Engineers recommends indoor CO2 concentrations be maintained below 1000 ppm in schools and 800 ppm in offices.
  • The Federal Environment Agency of Germany recommends classrooms and offices to not exceed 1,000 ppm.
  • In Ireland, CO2 monitors are being installed in classrooms with poor ventilation.
  • Germany’s Federal Environment Agency’s general guidelines for carbon dioxide in indoor air classifies any CO2 concentration between 1,000 and 2,000 ppm as questionable; anything above 2,000 is unacceptable.

    Which Is the Best CO2 Monitor for Classrooms?

    A monitor should ideally meet the AB841 requirements to be used within a classroom. There are some CO2 monitors that have been specifically designed for this purpose and are used in classrooms across California. See the video below for more information.

    REVIEW: Basic CO2 Meter Review

    Our CO2 monitor features advanced NDIR sensor technology that can detect as low as 1ppm, ensuring that you have accurate readings. And with a 10-year lifespan, you can trust that this monitor will last you a long time.

    Basic CO2 Meter by Forensics

    One of the standout features of this CO2 meter is its Li-Ion battery, which can be recharged via USB and provides up to 8 hours of operation. This makes it a great option for those who want a portable and convenient CO2 monitor.

    Additionally, the Basic CO2 Meter by Forensics is easy to use and not complex, making it a great choice for those who want a basic and accurate CO2 monitor. It's also stable on a table or can be mounted onto a wall for added convenience.

    Key Features

    When it comes to purchasing a CO2 monitor, it's important to consider the key features that will make it stand out from the rest. We've taken a closer look at the Basic CO2 Meter by Forensics and highlighted its standout features below.


    The Basic CO2 Meter by Forensics is a versatile device that can be used in a variety of settings. Whether you're monitoring the air quality in your home, office, gym, or car, this CO2 monitor can provide accurate readings to help you make informed decisions about your environment.


    One of the standout features of the Basic CO2 Meter by Forensics is its accuracy. With advanced NDIR sensor technology, this CO2 monitor can detect levels as low as 1ppm, ensuring that you get reliable and precise readings every time. Additionally, this device has a 10-year life, so you can trust that it will continue to provide accurate readings for years to come.


    The Basic CO2 Meter by Forensics is powered by a Li-Ion battery that can be recharged via USB. With up to 8 hours of operation on a single charge, this device provides reliable and long-lasting performance. Additionally, the device can also be powered with direct USB power, providing even more flexibility in how you use it.


    One of the best things about the Basic CO2 Meter by Forensics is how easy it is to use. This device is not complex and provides a basic and accurate CO2 reading. It can be placed on a table or mounted onto a wall, making it a versatile option for any environment.


    Forensics Detectors is a trusted brand in the CO2 monitoring industry, and the Basic CO2 Meter is no exception. With a 1-year limited warranty and 100% quality guarantee, you can trust that this device will provide reliable and accurate readings every time.

    Pros and Cons

    When considering the Basic CO2 Meter by Forensics, it's important to weigh the pros and cons to determine if it's the right fit for your needs. Here are some key factors to consider:


    • Accurate readings: The Basic CO2 Meter uses advanced NDIR sensor technology to detect CO2 levels as low as 1ppm, making it a reliable tool for monitoring air quality in various settings.
    • Easy to use: The device is simple to operate and not overly complex, making it a great option for those who want a basic and accurate CO2 monitor. It can be placed on a table or mounted on a wall for convenience.
    • Long battery life: The device is powered by a Li-Ion battery that can be recharged via USB, providing up to 8 hours of operation. It can also be powered directly by USB, giving you flexibility in how you use it.
    • Stylish design: The Basic CO2 Meter has a sleek and modern design that will fit in well with any decor. It's also compact and easy to transport, making it a great option for use in a variety of settings.
    • Trusted brand: Forensics Detectors FD offers a 1-year limited warranty and 100% quality guarantee, giving you peace of mind when purchasing this product.


    • Annoying alarm: Some users have reported that the alarm on the Basic CO2 Meter is loud and irritating. While this can be a useful feature in some settings, it may be a nuisance in others.
      • UPDATE: Good news is that we have implemented a MUTE function to overcome this early annoyance from customers.
    • Limited features: The Basic CO2 Meter is a simple and straightforward device, which may not be ideal for those who want more advanced features or data tracking capabilities.
      • UPDATE: We have deliberately removed advanced features to make this unit easy to use for all people of all ages and backgrounds.

    Overall, the Basic CO2 Meter by Forensics is a solid option for those in need of a basic and reliable CO2 monitor. While it may not have all the bells and whistles of more advanced models, its accuracy, ease of use, and stylish design make it a great choice for a variety of settings.

    Final Words

    Gas detection has become a focal point in ensuring the safety of teachers and students in classrooms since the pandemic. School districts have implemented enhanced air quality measures, including improved ventilation and CO2 monitoring, to mitigate the risk of airborne pathogens. Parents and guardians are encouraged to engage with their school districts and inquire about the specific measures adopted to enhance classroom air quality, such as updated protocols and equipment. Monitoring carbon dioxide levels through gas detection is crucial for children's safety, as elevated CO2 can indicate the presence of airborne pathogens, a critical insight gained from the COVID-19 pandemic. The heightened awareness of indoor air quality's importance has prompted school districts to proactively improve ventilation and CO2 surveillance, demonstrating their commitment to the well-being of students in the post-pandemic era.


    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 enjoying the outdoors.

    Read more about Forensics Detectors here.

    Phone: +1 424-341-3886