Back to school COVID-19 prevention demands smart strategies for a safe learning environment. Administrators and educators in school districts open for in-person learning must rethink their resources, infrastructure, and staffing levels in order to provide the best possible learning environment (1).

COVID-19 has required that communities and governments decide on the right balance between virtual and in-person learning, implementing public policies that help keep schools open, and implementing COVID-19 safety protocols in group settings.

Students and faculty face potential COVID-19 school risks

All teachers, parents, faculty, and students, in particular those who are unvaccinated, are at higher risk of COVID-19 infection in any public setting, including schools.

Young people are at risk for COVID-19 infection and severe health issues, including (2):

• difficulty breathing
• acute respiratory distress syndrome
• multiorgan system dysfunction
• on rare occasions, death

Children with underlying pulmonary or immunocompromising conditions could have more serious symptoms than other children.

Additionally, non-white communities have suffered far more fatalities proportionally than white communities. A 2020 report from the Centers for Disease Control and Prevention (CDC) determined that between February 12 and July 31, Hispanic, Black, and American Indian/Alaskan Native persons made up 78 percent of American children who died from COVID-19 and associated health complications (3).

However, children and teens seem to have a lower risk of becoming seriously ill than other age demographics.

A 2020 study published in Nature Medicine found that children and teens under the age of 20 were roughly half as likely to become infected from COVID-19 as people over the age of 20. Clinical symptoms might occur an average of 21 percent of the time among people aged 10 to 19, compared to 69 percent in people over 70 years old (4).

However, even with fewer infections in children than in adults, there have been COVID-19 outbreaks connected to childcare facilities and schools, with children spreading the virus to one another, to adults, and to caregivers (5) (6). The exact role of children in transmission isn’t fully mapped out, but there is evidence that teenagers can transmit the virus as easily as adults.

Additionally, unvaccinated teachers and staff face a serious health risk just by reporting to work. One in four teachers or faculty, or nearly 1.5 million adults, are at increased risk of getting seriously ill from COVID-19 due to a pre-existing condition, according to a 2020 brief from the Kaiser Family Foundation (7).

Poor air quality contributes to poor health

Proper school building ventilation alone will not prevent the spread of COVID-19. Clean air and controlling the source of infection in combination with improved ventilation can help reduce the spread of viruses and bacteria (8).

COVID-19 can be spread by touching infected people, surfaces, and objects (9).It can also be spread by droplets. Source control measures like wearing masks, staying home while sick, and social distancing directly help reduce large droplet transmission by limiting person-to-person contact infection generally within six feet of one another.

Another means of transmission is airborne transmission. Much smaller respiratory droplets can leave infectious viral particles lingering in the air for hours and moving greater distances through air currents (10).

Ventilation moves air and with it, aerosolized, small droplets of infectious particles around a building. However, high-quality air filtration, such as HyperHEPA technology, can trap airborne particulate pollutants, viruses, and bacteria. Cleaning the air through filtration can help reduce the risk of COVID-19 by capturing particles as small as 0.003 microns and reducing their concentrations in the air.

Natural ventilation solutions like opening windows or holding classes in tents outdoors may help control aerosols, but they’re not practical in most winter climates. And with high-quality air filtration, mechanical ventilation doesn’t need to exceed the building code requirements, thus maintaining higher levels of energy efficiency.

Furthermore, when schools elect to incorporate high-quality air filtration, heating, ventilation, and air conditioning (HVAC) systems do not need to run 100% of the time, which further decreases energy requirements.Another benefit of HyperHEPA technology is low pressure drop, allowing filter replacements to occur only once per year (based on average 50% duty cycle) due to highly efficient filtration material.

The U.S. Centers for Disease Control and Prevention offers guidelines on how to use ventilation in schools and childcare programs (11).Guidance emphasizes that improving the level of air filtration without significantly reducing airflow is an important component of helping maintain a healthy environment.

While better ventilation can help reduce COVID-19 transmission, outdoor airflow can also introduce outdoor airborne pollutants and allergens into schools.

There are many other pollutant sources in schools, including:

• cleaning products
• tightly sealed new schools with insufficient ventilation
• off-gassed chemicals like formaldehyde
• lead, asbestos, and radon contamination in older school
• mold
• particulate pollution, such asPM2.5 andPM10

A number of studies have shown that high levels of particulate matter in the environment has been associated with increased COVID-19 symptoms(12) (13) (14).

A study in Science Advances found that for every increase of 1 microgram per cubic meter (𝜇g/m3) of PM2.5, the risk of severe or fatal COVID-19 symptoms increased by 8%.

Those same researchers later updated their study and determined that long-term exposure to PM2.5 was associated with greater COVID-19 mortality rates in U.S. counties.

A further study in Science of the Total Environment determined that particulate matter was directly connected to new cases of COVID-19 in Milan, Italy.

PM2.5, or fine particulate matter, has a diameter of 2.5 microns or less. It’s considered dangerous for both children and adults, as PM2.5 can enter the lungs through air passageways and get into the bloodstream (15).Components of PM2.5 include:

• dust
• soot
• dirt
• smoke
• salt
• acids
• metals

A 2019 study published in BMC Public Health has linked influenza-like illness to PM2.5, while respiratory disease has long been associated with exposure to the pollutant (16).

In a 2010 study, children in six French urban communities were studied for three years to determine the long-term health impacts of air pollution (17).The results, published in the European Respiratory Journal, found a number of health concerns associated with PM10, PM2.5, and gas pollutant exposure, such as:

• asthma
• eczema
• lifetime allergic rhinitis
• pollen sensitivity

Air pollution may even harm children’s ability to learn. A 2015 study published in Population and Environment found that even when accounting for other factors, students exposed to traffic-related pollutants suffer from lower GPAs (18).

How clean air can help reduce COVID-19 exposure in schools

Thorough and efficient indoor air cleaning in schools can help to reduce exposure to viruses and COVID-19.

Airborne COVID-19 particles are generally between 0.06-0.14 microns (19).High-performing air cleaners like the CleanZone SL and NanoMax air filters are capable of capturing particles measuring as small as 0.003 microns.

An important health consideration for schools with in-person learning is HVAC-based air cleaning. Filters like the IQAir NanoMax filter remove PM10 coarse particles (< 10 μm), PM2.5 fine particles (< 2.5 μm), and ultrafine particles (< 0.1 microns).

NanoMax filters capture up to 90 percent of particles down to 0.003 microns, including viruses, bacteria, allergens, and air pollutants. NanoMax filters can be used in almost any school HVAC system and engineered to meet your school's exact HVAC requirements.

The CleanZone SL air purifier removes 95 percent of all particles 0.003 microns or larger.

Benefits of the CleanZone SL include:

• capable of filtering ultrafine particles down to 0.003 microns in diameter, including viruses
• cleans all air in a 1,000 square-foot space once every 15 minutes
• viruses and bacteria are filtered through HyperHEPA filter four times an hour

Faculty and administrators can actively monitor indoor and outdoor air quality with AirVisual Series air quality monitors. These monitors can detect PM2.5 pollutants, forecast air quality for the next 72 hours, and provide administrators with alerts when the air quality falls below user-determined standards.

Schools can also look into the IQAir Clean Air Schools program for help in reducing airborne illnesses. Air Quality Experts provide air purification installation services and solutions tailored to the needs of individual schools.

Recommended approaches for COVID-19 school control

Besides source control, ventilation, and air purification, there are many school policies recommended by health experts.

The CDC and the Public Health Agency of Canada encourage several strategies for reducing COVID-19 spread in schools with in-person learning, including (20) (21) (22):

• smaller class sizes
• a mix of virtual learning and in-person learning, as appropriate to the student
• grouping students into small social bubbles, or cohorts
• groups of students and their teachers avoiding contact with other groups
• providing tissues and touchless trash cans
• applying alternating and staggered schedules
• objects and food are never shared between students and teachers
• everyone in a school must wear a mask and socially distance
• providing hand sanitizer, including at lunch checkouts
• regular hand washing and covering coughs and sneezes
• avoiding any self-serve food or drink options
• increasing barriers and dividers at desks, offices, and counters where feasible
• any person with COVID-19 symptoms must stay home

Vaccinated teachers and staff should follow additional CDC guidelines, including (23):

• wear masks with unvaccinated people and in public places
• continue to socially distance with unvaccinated people and in public places
• get tested if experiencing COVID-19 symptoms

While everyone should wear masks in schools, some masks help protect better than others. Masks that can be worn include:

• scarves and fabric masks: one protective layer that blocks coarse droplets
• surgical masks: a single use item with two protective layers
• KN95 / N95 / FFP2 respirators: several protective layers that help block coarse, fine, and ultrafine droplets

Common areas that are shared between groups like playgrounds and cafeterias should be closed when possible. For example, students should eat in classrooms or outdoors rather than in cafeterias. If that’s not an option, common area use must be staggered for groups and all objects in the area should be cleaned and disinfected between group visits.

Classroom layout can be a challenge but is another essential strategy. All seating should be six feet apart whenever possible. Desks or table seating should all face in one direction.

Both virtual learning and in-person teaching classroom restrictions have encouraged some school systems to hire more teachers. In October 2020, Ontario allocated $35 million to hire more teachers for Ottawa, Peel, Toronto, North York, and East York(24).Teachers were hired to support virtual learning and promote physical distancing between students for in-person classes. The province also hired more in-school nurses and custodians to increase cleanings.

National virtual class or in-person class policies

In concert with state, provincial, and federal policy, communities have been deciding for themselves which mix of virtual and in-person education is best for them. There has been no global consensus on when and where to implement virtual or in-person education.

In-person learning benefits

While some governments have expressed that keeping their schools open or reopening them is their priority, it can be a challenge to balance health and safety concerns with the benefits of in-person learning (25).

While closing schools removes a source of COVID-19 risk for faculty, parents, and students, virtual-learning and school closures have negative impacts on children and their communities. There are societal and students benefits to in-person learning, such as (26) (27):

• nutritional access
• welfare services and preventing violence against children
• socialization skill-building
• psychological well-being through reduced isolation
• allows parents to return to work and avoid additional childcare costs
• better ergonomics
• best possible learning environment

Additionally, some students with physical or learning disabilities may benefit more from in-person learning strategies than virtual classrooms, especially if a school system’s virtual schools create accessibility issues (28).

The takeaway

There are year-round health concerns in and out of schools for children, from the physical worries like pollution, asthma, and allergies to isolation and learning access difficulties for virtual learners.

COVID-19 presents an additional health challenge on top of these existing issues for unvaccinated students and faculty alike. The long-term efficacy of vaccines, including their effectiveness against newer variants of COVID-19, is still to be determined. Until herd immunity is achieved, additional cautions should still be taken even after vaccination.

When schools reopen or remain open during the COVID-19 epidemic, administrators will need to focus on maintaining source control through masks and social distancing while developing air cleaning strategies to help control pollutants and microorganisms in the environment.

Implementing public health officials’ recommended procedures – controlling the source of infection – can reduce infection risk in schools. Cleaning the air can also help keep students and faculty safe from harmful pollutants and airborne bacteria, viruses, and fungal spores.