Indoor Air Quality in Classrooms and COVID19

student poor iaq covid

The effect of poor indoor air quality in classrooms has been known for years. Chronic illnesses, reduced cognitive abilities, sleepiness, and increased absenteeism have all been attributed to poor IAQ – specifically elevated CO2 levels. What’s more concerning today is the effect COVID19 will have on air quality and how will it effect children and schools.

Indoor air quality can be impacted by many factors:

  • Dust and dander
  • Germs and airborne microbes
  • Mold and mildew
  • Volatile Organic compounds (VOCs) from carpets, paint, and new drywall
  • Asbestos
  • Carbon dioxide (CO2)

While most parents know about the impact of dust, mold, mildew, and other particles on their children, they are often unaware of the impact of high levels of CO2 combined with the more recent airborne infectious disease – COVID19.

While masks are stated to do their job in preventing the spread of the virus, unavoidably, the disease will find its way through the air – and then what’s next?

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) continues to be an invaluable resource in defining proper CO2 levels for commercial and residential buildings as well as schools. ASHRAE Standard 62-2001 “provide(s) indoor air quality that will be acceptable to human occupants and is intended to minimize the potential for adverse health effects.”

Building codes in most states reference Standard 62, either in part or in its entirety, as part of their definition for minimum ventilation requirements.

According to ASHRAE, the recommended CO2 level in buildings should be no more than 700 parts per million (ppm) above outdoor air. Since outdoor air is approximately 400ppm, indoor CO2 levels should be no more than 1,100 ppm. Note that this guideline is not designed to limit the amount of CO2, but rather to indicate that a proper level of clean air (15-20 CFM/person) is being distributed in a classroom. And OSHA and the US Green Building Council have even tighter indoor CO2 recommendations.

Following on the research already conducted on indoor air quality additional studies are now being formed like that at the University of Colorado, focusing on how to control the transmission of airborne infectious diseases indoors, specifically in the classroom or university setting.

Similar to to the carbon dioxide (CO2) research, the results are that once the virus escapes into the classroom you have two choices:

  • Ventilate the building (bring fresh air in from outside) or 
  • Remove the virus from the air inside the building (filtration/HVAC systems)

Currently, additional inspection criteria and standards are being developed, like that of the New York City Department of Health and Mental Hygiene. These standards are based on guidance by the CDC and WHO to ensure proper monitoring systems are in place in classrooms and group spaces to achieve sufficient ventilation. 

The New York City standard states, “Proper air ventilation is key to stop the spread of COVID-19. Per CDC guidance, it is highly recommended that schools:

  • Increase the amount of fresh air in classrooms – whether by natural or mechanical means,
  • Inspect, repair, and increase air filtration,
  • Inspect and repair supply and exhaust fans,
  • Deploy portable High-Efficiency Particulate Air (HEPA) filters.
  • Ensure ventilation systems operate properly and provide acceptable indoor air quality for the current occupancy level for each space.

How common is poor IAQ and high CO2 levels?

While exact figures are not known, according to the National Center for Education Statistics, there are almost 99,000 public K-12 schools in America, and the average school building is 42 years old. Of these, 30% reported heating system, air conditioning system, and ventilation/filtration systems to be in fair to poor condition.

One of the reasons is that many school buildings were built in the 1960s and 1970s to solve two problems: the high number of “baby boomer” children coming into the public school system, and the increasing cost of energy needed to heat or cool old school buildings. Therefore, many of the schools built during those years used “modern” energy-saving features like windows that could not be opened.  

While “closing the envelope” reduced the cost to heat and cool the buildings, ironically, it resulted in “sealed” classrooms that trapped poor air quality, contaminants, and drove up CO2 levels past acceptable limits.

Fresh, Outside Air is the Answer.

As more and more studies continue to show the negative effects of poor indoor air quality, not only does poor air circulation result in high levels of CO2 but also high levels of airborne illness (COVID). While studies have shown that high levels of carbon dioxide have reduced the amount of oxygen to the brain, studies have also shown that high levels of airborne illness tend to exasperate in rooms with poor levels of air circulation. Poor air circulation not only results in high levels of CO2 and viruses, but also high levels of dust, dander, germs, microbes, and other particles.

The ideal indoor environment is one with (you guessed it) lots of outside, fresh air replacing the stale, contaminated air inside. In indoor environments such as classrooms, it is important to note that quality HVAC should be properly in place. Like homes that filter in outside air through windows/doors, those universities and classrooms with limited entryways need an HVAC system to properly pump in outside air and eliminate potential exposure.

Unfortunately, studies have shown that many universities, classrooms, and indoor learning centers, do not have the proper ventilation rates, to begin with. This has resulted in increases in child illness, lack of productivity, and uninterest in learning. Additionally, a review of referred archival journals commissioned by Berkeley Lab for their Scientific Findings Resource Bank concluded that:

The available research provided “compelling evidence of an association of improved student performance with increased classroom ventilation rates.” Overall, eight out of 11 studies reported statistically significant improvements in at least some measures of student performance with increased ventilation rates or lower carbon dioxide concentrations, and a ninth study reported a statistically significant improvement in performance when applying a less stringent than typical criterion for statistical significance. Five of the studies were intervention studies that increased ventilation rates and measured changes in performance within students.

Time-average carbon dioxide concentrations in classrooms, Berkeley Lab

How to Improve your Indoor Air Quality (IAQ)?

The simplest solution is to talk to the building supervisor in your child’s school. Indoor air quality is normally monitored in all school buildings, and the results are available to the public. Additionally, you can research online “indoor air quality in schools (your state)” or visit

For those teachers, professors, and counselors looking for an indication of proper indoor air quality, indoor air quality monitors such as the IAQ-MAX CO2 Monitor and Data Logger can be used to properly monitor and measure carbon dioxide, temperature, relative humidity, and barometric pressure – in real-time.

IAQ MAX indoor air quality monitor and data logger

By utilizing an indoor air quality monitor such as the IAQ-MAX, you can rest assured that should levels exceed the normal threshold, the device will provide a prompt indication. With quick, accurate, and advanced sensor technology the IAQ-MAX will alert the user via audible/visual alarms that proper ventilation is required for occupant and student comfort. 

When reflecting on what is happening within our environment and being able to provide an exclusive IAQ solution to mitigate these risks and ensure overall health and well-being, CO2Meter could not be prouder of the IAQ-MAX and its capabilities as it continues to impact the industry. 

Currently, the IAQ-MAX continues to be utilized across homes, offices, and classrooms to provides proper IAQ monitoring and data logging capabilities to further analyze measurements over time and ensure proper ventilation protocol to HVAC professionals.

For further information on carbon dioxide, proper indoor air quality, and ventilation best practices – contact us today: 

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