**Please Note: The CO2Meter offices will be closed in observance of the US Thanksgiving holiday beginning at 5:00 pm et. Wednesday, November 24. All operations will reopen Monday, November 29 at 8:30 am et. Orders placed after noon et. November 24 will be fulfilled on November 29. Happy Holiday!**


CO2 Coverage, COVID-19, and Indoor Air Transmission

CO2 monitoring

CO2 Coverage, COVID-19, and Indoor Air Transmission

The beginning of cold and flu season is always the harbinger of conversations about indoor air quality.  Like clockwork, each fall, the TV ads start about sniffles, and tissues with aloe, as well as all the pills, sprays, and contraptions that help prevent or heal your symptoms.

COVID-19 accentuated these conversations as researchers began to better understand how COVID was released, traveled, and “hung” in confined spaces.  From studies such as the dispersion patterns of exhaled breath, to the viability of masks and filters to prevent the spread of the virus, research started to be released this fall to better inform public health officials and the public as to the true nature and effects of the virus in the air.

The Centers of Disease Control and Prevention (CDC) discusses primarily that the principal mode by which people are infected with the SARS-CoV-2 virus is through exposure to respiratory droplets carrying the infectious virus. To provide further perspective, respiratory droplets are created through exhalation such as breathing, speaking, coughing, sneezing, or singing and can also cover a wide range of droplet sizes that may be divided into two basic categories based on how long they can remain held in the air.

Categories of Respiratory Droplets:

  • Larger Droplets: some of which are visible and that fall out of the air rapidly within seconds to minutes while close to the source.
  • Smaller Droplets: these are formed when small droplets dry quickly in airstream and can remain suspended for many minutes to hours and travel far from the source on air currents.

Indoor CO2 Measurements through Use of Sensors

Almost every study has concluded that the best indicator of the potential for virus transmission indoors (home, office, or school) is the carbon dioxide (CO2) concentration. While lower CO2 concentrations indicate that enough fresh air is being brought in from outside the building higher CO2 concentrations indicate the lack of fresh air being brought in from outside the building.

Measuring carbon dioxide (CO2) is simple, cost effective, and can be a fun learning experience, too. By understanding that CO2 levels are a vital part of improving Indoor Air Quality (IAQ) individuals can dramatically influence a more positive lifestyle and well-being. Poor Indoor Air Quality can lead to reduced cognitive abilities, respiratory ailments live asthma and allergies, an increased rate of simple viruses like the flu and common cold, and the spread of severe viruses like COVID-19. By monitoring CO2 levels throughout indoor spaces individuals can prevent airborne illness from being transported as well as create a healthier indoor air environments.  

One positive note from 2020 is the dramatic increase in education and information about Indoor Air Quality CO2 monitors. These devices are designed to provide fast, accurate, and simple measurements of the attributes of the air so that consumers, businesses, and public health officials can make intelligent decisions about the safety of indoor spaces. Typically, these devices will provide measurements for carbon dioxide (CO2), temperature, relative humidity, and sometimes particulate matter (dust, mold, pollen, etc.). Device characteristics vary but they may be battery powered or plugged in, may log data, or transmit the data wirelessly, and may activate your ventilation or HVAC system.

California State-Level Indoor Air Quality Program

On January 1, 2021 the state of California established a state-wide regulation intended to meet energy, sustainability, and improve indoor air quality (IAQ) standards throughout public school systems.

This regulation applies to all existing classrooms, projects for the construction of new classrooms, and alteration or modernization of existing classrooms. Of these amendments, the Division of the State Architect (DSA) directed that all classrooms, including existing classrooms, must be equipped with a carbon dioxide (CO2) monitor as a mechanism for providing and maintaining proper ventilation and indoor air quality (IAQ).

Requirements of CO2 Monitors

Plans submitted to DSA for the construction of new classrooms, and alteration or modernization of existing classrooms must include a carbon dioxide (CO2) monitoring device meeting the following requirements:

  • The monitor is hard-wired or plugged-in and 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 displays the CO2 readings to the teacher through a display on the device or other means such as a web-based applications or cellular phone application.
  • The monitor provides a notification through a visual indicator on the monitor, such as an indicator light, or other alert system, such as an electronic mail, text, or cellular telephone application, when the carbon dioxide levels in the classroom have exceeded 1,100ppm.
  • The monitor maintains a record of previous data that includes at least the maximum carbon dioxide concentration measured.
  • The monitor has a range of 400ppm to 2000ppm or greater.
  • (a) The monitor is certified by the manufacturer to be accurate within 75ppm at 1,000ppm carbon dioxide concentration and is certified by the manufacturer to require calibration no more frequently than once every five years.
  • (b) If a classroom CO2 concentration exceeds 1,100ppm more than once a week as observed by the teacher or the facilities staff, the classroom ventilation rates shall be adjusted by qualified personnel toe ensure peak carbon dioxide concentrations in the classroom remain below the maximum allowable CO2 ppm setpoint. Verification of the installation of carbon dioxide monitors in all classrooms shall be included in the assessment report required pursuant to Section 1626.
  • (c) The requirements of paragraphs (1) to (6), inclusive of subdivision.

Fortunately, CO2Meter has long been recognized as a leading source for CO2 monitoring and indoor air quality solutions, providing customers such as those in the state of California, with the roper CO2 monitors that will not only meet this standard but also mitigate the COVID-19 virus and ensure a healthier indoor space for classrooms.

Two Indoor Air Quality (IAQ) solutions that meet the need for this requirement in public school systems are the Aranet4 HOME Indoor Air Quality Monitor and the IAQ MAX CO2 Monitor and Data Logger.

Aranet4 HOME Indoor Air Quality Monitor

Pictured Above, the Aranet4 HOME Indoor Air Quality Monitor

These devices are both designed to provide a sleek, modern, IAQ solution in order to monitor CO2, Temperature, %RH, and Barometric Pressure in indoor air environments. In addition the devices provide an easy understanding of the CO2 levels in the space with large displays to show CO2, Temperature, Relative Humidity, and Barometric Pressure. Administrators, faculty, and students will gain an easy understanding of when more ventilation is needed in the space due to the visual and audible alarms, as well as understand how indoor air impacts the overall health, cognitive abilities, and well-being of each other.

Most consumers and business owners need simple, low cost, easy to use devices – just something to tell them if their home, school, business, or office is getting enough fresh air. Whether you see those values on a large display or on your phone with the Aranet4 HOME, having the information is a powerful tool in keeping yourself, family, employees, and customers as safe as possible.

Recommended CO2 IAQ Monitor Coverage Areas

The two most frequent questions we get asked about IAQ are: what are safe levels, and how many sensors do I need?

For more than a dozen years that standard thinking about safe indoor CO2 levels has been “anything below 800 is good”. That threshold is not a randomly selected number, however. Years of research from the Occupational Safety and Health Administration (OSHA), the National Institute of Occupational Safety and Health (NIOSH), the American Society of Heating, Refrigerating, Air Conditioning Engineers (ASHRAE), the United States Green Building Council (USGBC), and other groups have determined that CO2 levels indoors below 800 ppm are an indicator of good indoor air quality. 

Whether that air quality level is achieved through opening fresh air dampers on your HVAC system or by creating cross ventilation through opening doors and windows, the important factor is the continuous and measured low CO2 concentrations.

The average indoor air quality device will cover approximately 1,500 square feet (length X width of the floor space). Be mindful that the calculation assumes a completely open floor plan however – think of a garage or a warehouse. 

The actual coverage area for sensors depends on several factors, primarily, how many enclosed spaces do you have? 

Schools have dozens of individual or enclosed spaces because the classrooms are all separated. Modern offices often have open floor plans except for executive offices. Local breweries may have open concepts too that include brewery or tasting rooms. And modern homes often have open floor plans but enclosed office and bedroom spaces. 

Below are four floor plans for a typical school, office, home, and micro-brewery that will give you and idea of the coverage area for IAQ devices.


Classroom Coverage Area

Classroom Coverage Area

Office CO2 Sensor Coverage Area

Office CO2 Sensor Coverage Area

Home CO2 Sensor Coverage Area

Home CO2 Sensor Coverage Area

Commercial  CO2 Sensor Coverage Area

Commercial  CO2 Sensor Coverage Area


Please Note, that the circles are not to scale and merely represent what 1,500 sq. feet per device might look like.

As more and more businesses work towards reopening and improving indoor air quality the use of carbon dioxide monitors will continue to provide an essential solution across the globe. The trend is catching on fast throughout not only the united States but from a global reach as well in terms of research and continued standards being created for industries such as restaurants, universities, corporate offices, commercial businesses, and gymnasiums.

Being able to ensure a healthier lifestyle and reduce the transmission of airborne illnesses, is quite simply, a must in todays society.  Knowing how "safe" your space is can be an incredibly powerful tool and CO2 monitors are the best resource for that information. This way, you can ensure peace of mind when indoors and have some insight into ventilation, which is really difficult to figure out – otherwise.

For more information in indoor air quality solutions and carbon dioxide monitoring for your application or industry, contact a CO2 expert at Sales@CO2Meter.com or visit us, here.  

Older Post Newer Post