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Improving ventilation and indoor air quality inside academic facilities can enhance infectious disease resilience.

The importance of indoor air quality in higher education

Improving ventilation and cleaning the air inside academic facilities can enhance infectious disease resilience--and it's why indoor air quality is paramount

By Frederik Hendriksen, Co-Founder, Rensair December 17th, 2021

In the wake of the COVID-19 pandemic, public health has become a serious priority, especially regarding the education system and in-person learning. 

At the start of the outbreak, educators, eager to provide a safe learning environment, moved in-person instruction to a virtual format. Yet, after more than a year of online schooling, students and faculty are eager to return to the classroom. 

College and university leaders acknowledge that in-person interaction with professors and other students is an important aspect of higher education. But returning to the classroom means moving students and educators inside, breathing the same air. And now, there’s the potential threat of COVID-19’s Delta variant generating a resurgence of infection. 

Higher education professionals are responding to the challenge by implementing recommended strategies such as mask and vaccination adherence. They are also being advised to put critical focus on improving the once overlooked factor of indoor air quality if they are to protect the health and safety of their students, faculty and staff. 

Why focus on indoor air quality? 

At first, knowing how coronavirus was spread, and what to do to mitigate infection, was unclear. People grasped for solutions. Hand sanitizers flew off the shelves and people spent their days scrubbing down surfaces.

We now have sound evidence, thanks to science, that the virus is most often spread via airborne aerosols. When people sneeze, cough, or talk they expel particles that contain droplets and aerosols. Aerosols are light and can drift and linger in the air for hours, particularly indoors, causing potential transmission of the coronavirus. 

The World Health Organization (WHO) says hand sanitizing and surface cleaning does not offer enough protection in indoor spaces. So, improving indoor air quality to mitigate airborne infection in our institutes of higher education is of utmost concern. To be safe, indoor air requires purifying potential airborne contaminants. 

The Centers for Disease Control and Prevention (CDC) promotes a multi-layered approach. They say getting vaccinated and wearing a mask indoors in public can maximize your protection from COVID-19 and the Delta variant. They also support improving building ventilation as a critical component in reducing the spread of disease and lowering the risk of exposure to COVID-19. 

The U.S. Department of Education has issued a report asserting that “clean air is essential for living and learning, and effective ventilation is an important part of COVID-19 prevention.” They noted that ventilation continues to be a topmost concern and that proper ventilation, with other mitigation measures, can reduce the possibility of spreading disease.

The challenge of cleaning indoor air 

So we know that improving ventilation and cleaning the air inside our academic facilities can enhance infectious disease resilience. Yet, many educators have found that doing so can be a challenge.

Poor ventilation in school buildings is quite prevalent, especially in older buildings. A report from the Government Accountability Office in June 2020 determined that one-third of public schools are estimated to have inadequate heating ventilation and air conditioning (HVAC) systems. 

In April 2021, The Lancet’s COVID-19 Commission published a paper offering strategies and warnings for schools looking to improve their buildings ventilation and air cleaning. According to the report, institutes of education are chronically under ventilated. They assert that most school buildings do not even meet the minimum standards set by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE). 

Education leaders have found that retrofitting their entire HVAC system is most often out of the question. The process can be complicated, lengthy, and the cost alone makes this choice untenable. The good news is fully integrated ventilation systems are not the only solution. 

Studies have found that portable air purifiers that are properly designed can be incorporated with existing HVAC systems to create an optimal air change per hour.  ASHRAE has judged that five to six air exchanges per hour are effective in a classroom of 1,000 square feet with an 8-foot ceiling. Compared to a complete retrofit, the cost savings of using portable air purifiers are significant and because installation is not required, their use can be implemented fast and with ease.

In July 2021, it was reported that, to help control the spread of COVID-19, the education department would provide all 56,000 New York City public school classrooms with two air purifiers by September. This is a positive step and similar initiatives are under way in other states. 

Yet, not every portable air purifier is up to the job. It’s important to choose a unit that will be effective. What type of portable air purifier do experts recommend? 

The right air purifying technology

In her open letter, Dr. Marwa Zaatari, Indoor Air Quality expert and Member of the Board of Directors at U.S. Green Building Council, advocates caution when specifying air purification devices. She focuses on the technology behind the device. Dr. Zaatari endorses scientifically proven measures, including portable HEPA (high-efficiency particulate absorbing) filter units with UVC (germicidal ultraviolet light) systems as efficient, practical, easy to implement, and not costly.

Government programming has supported this recommendation. The American Rescue Plan (ARP), that allocated nearly $125 billion for education, approved the purchase of portable air filtration units, such as HEPA air filters, to improve the indoor air quality of in-person instruction. 

The Higher Education Emergency Relief Fund (HEERF lll), authorized by the ARP, provided $39 billion to support institutions of higher learning. A portion of funds awarded was designated to “implement evidence-based practices to monitor and suppress coronavirus in accordance with public health guidelines.” Public health guidelines include the recommendations of the CDC, which clearly state in their June 2021 update that portable air purifiers with a HEPA filter and high-powered fan system are “the preferred option for auxiliary air cleaning.” The update also supports the use of germicidal UVC as a supplemental treatment to inactivate the coronavirus.

And in their October 2021 webinar, the Environmental Protection Agency (EPA) Indoor Environments Division discussed proven strategies that schools can implement to improve indoor air quality. They cited increasing ventilation rates, using efficient HEPA filters, and supplementing with portable air cleaners as critical for healthy air in the school environment. 

HEPA filtration and UVC light

Why are HEPA filtration and UVC light key components of an efficient and effective portable air purifier? To put it simply, HEPA filtration captures COVID-19 and UVC light kills it. 

The CDC breaks down the science behind HEPA filters: “Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 micrometer (µm) in size. By definition, a HEPA filter is at least 99.97% efficient at capturing particles 0.3 µm in size. This 0.3 µm particle approximates the most penetrating particle size (MPPS) through the filter. HEPA filters are even more efficient at capturing particles larger and smaller than the MPPS. Thus, HEPA filters are no less than 99.97% efficient at capturing human-generated viral particles associated with SARS-CoV-2.”

The CDC also explains that germicidal UVC technology uses “ultraviolet (UV) energy to inactivate (kill) microorganisms, including viruses, when designed and installed correctly.”

When selecting a portable system, these experts also recommend choosing one that has a powerful fan and is appropriately sized for the area in which it will be used.

Prepared for the future 

The COVID-19 pandemic has illustrated how poor indoor air quality (IAQ) has a direct effect on our health. Sometimes the impact of poor IAQ can be subtle. It does not always produce such easily recognized symptoms as COVID-19. But if not attended to, poor IAQ will continue to be a threat to our well-being. 

EPA studies of human exposure to air pollutants reveal that indoor levels of pollutants may be two to five times, and occasionally more than 100 times, higher than outdoor levels. These levels of indoor air pollutants are of particular concern, because most people spend about 90 percent of their time indoors.

In fact, EPA’s Science Advisory Board has ranked indoor air pollution as one of the top five environmental risks to public health. They have found that, “good IAQ is an important component of a healthy indoor environment, and can help schools reach their primary goal of educating children.”

The Harvard Center for Health and the Global Environment reports that a major new study on the impact of green buildings showed that, with better air quality, cognitive scores were 61% higher across nine functional domains including crisis response, strategy, and focused activity level. 

The EPA says, “Healthy indoor air quality can promote a healthy learning environment, reduce absenteeism, impact test scores and enhance student and staff productivity.” 

Institutes of higher education would be wise to attend to their indoor air quality not only as a mitigating factor of COVID-19, but as an investment in the educational environment beyond the pandemic.

About the Author:

Frederik Hendriksen is Co-founder Rensair, an international company that protects and enhances lives through clean air. The Rensair air purifier was developed by his father, Henrik Hendriksen, a highly experienced Danish ventilation engineer, to meet the strict air quality requirements of Scandinavian hospitals. After a career split between building and scaling companies in EMEA/Asia and financial services at Morgan Stanley, Frederik – along with twin brother and fellow Co-founder Christian – have expanded the company’s operations in Europe, North America, and Asia to meet commercial demand driven by the Coronavirus pandemic. Frederik is a Danish national resident in the UK. He has a BSc in International Business and MSc in Finance & Accounting from Copenhagen Business School.





Sound evidence


World Health Organization




U.S. Department of Education


Government Accountability Office






Open Letter


American Rescue Plan




June 2021


Environmental Protection Agency webinar


CDC breaks down the science


Indoor air pollution



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