How to become a Clean Air School

Clean air is critical in helping students and staff stay healthy.

But access to clean air has long been an issue for many schools. This is especially true for disadvantaged or underserved schools near major sources of air pollution.

Improving air quality in your school can seem complicated and daunting. But clean air can provide numerous returns by helping:

  • prevent illnesses from airborne infections
  • ensure that your school can conduct in-person classroom instruction
  • improve long-term, school-wide academic performance

Every school’s path to becoming a Clean Air School is unique. In many cases, schools can follow these steps for a comprehensive approach to air quality challenges that will best serve the needs of students and teachers:

  1. On-site air quality assessment
  2. Installation and maintenance
  3. Air quality verification and monitoring
  4. Maintenance and renewal

1. On-site air quality assessment

The first step toward clean air at school is a thorough evaluation and assessment (virtual or in-person) of the school site.

As you begin to determine your school’s air quality needs, several critical factors must be considered to identify specific air quality challenges and possible solutions.

Local sources of pollution

The degree to which your school is affected by air pollution is a major factor in determining your specific air filtration needs and how extensive filtration technology may be throughout your school site.

Schools located near highways, busy roads, or heavy industrial polluters like factories or ports may face higher levels of PM2.5,(particulate matter with a diameter size of 2.5 microns or smaller),ultrafine particles (UFPs), and chemicals that can be difficult to control.

Click here to see why particle size matters...

Air pollution and COVID-19 (a serious disease, often fatal, that is caused by the SARS-CoV-2 virus)outcomes are also closely linked. Common air pollutants, especially PM2.5, may increase the risk of illness or death from COVID-19.

In these cases, air filtration that can adequately address high volumes of both indoor and outdoor air pollution are necessary.

School age and HVAC design

The average school building in the United States is between 37 and 46 years old (1) (2).Heating, ventilation, and air conditioning (HVAC) design has changed dramatically during this period.

Some schools have central HVAC systems, while others may have individual heating and cooling units for every classroom. This can drastically alter the air filtration needs from school to school.


Maintenance and filter replacement are key to long-term air filtration performance. Proper installation and filter replacements must both be taken into account when budgeting for long-term air filtration needs.

Air pollution sources and HVAC system design both affect the type of solution you’ll need as well as how often you’ll need to replace filters. Schools in heavily polluted areas may require more frequent filter replacements as filters quickly build up with airborne particles.

Funding assistance

Funding assistance may be available for schools in need, but schools may face challenges with securing a budget for air quality improvements.

For more information or assistance on grants and funding, email or call 866-760-8180.

Expert consultation

In many cases, expert consultation is needed to adequately assess every factor relevant to purchasing, installing, and maintaining air filtration technologies.

An onsite or virtual evaluation conducted by subject matter experts in school air quality can help your school identify air quality issues and possible solutions with the following steps:

  1. building walkthrough to document facility details
  2. spot measurements of air quality indicators to assess major sources of air pollution
  3. inspection of air handlers and air distribution systems to determine filtration needs
  4. written report detailing air quality challenges and proposed solutions customized to your school’s needs

Localized air filtration solutions, such as stand-alone air purifiers, may be helpful for classrooms without centralized HVAC systems. A high-performance system can provide several full air changes per hour (ACH), removing up to 99.5% of airborne particles in a classroom.

Personal air purifiers can also help by providing individual desks and workstations with a direct supply of clean air, delivering air filtration efficiencies up to 99% for airborne particles.

However, customized minimum efficiency reporting value (MERV)16 HVAC air filtration is recommended to capture infectious particles and pollutants across the largest area possible.

How it works infographic

MERV 13 filtration is currently a popular choice for filtration in schools. But MERV 13 only captures up to 50% of airborne particles between 0.3-1.0 microns.

MERV 13, due to its lower efficiency, might require extensive mechanical ventilation. This reduces energy efficiency and may not be feasible during extreme weather.

MERV 16 is nearly twice as efficient as MERV 13, capturing up to 95% of airborne particles in the 0.3-1.0 micron range.

MERV 16 is nearly twice as efficient as MERV 13, capturing up to 95% of airborne particles in the 0.3-1.0 micron range (see Figure 1) and requiring little to no ventilation (3).

MERV air filtration efficiency for different particle sizes

Figure 1: MERV air filtration efficiency for different particle sizes. MERV 16 efficiencies are detailed at the bottom of the chart (Source: ASHRAE Standard 52.2-2017) (4).

During field tests in classrooms, MERV 16 filtration has met and even exceeded these efficiency ratings (5).

2. Installation and maintenance

Many schools may be eligible for turnkey air filtration solutions that have already been successfully designed and implemented for schools with similar air quality needs.

In schools where customization is necessary, a high degree of expertise may be required to properly install and maintain air filtration systems for maximum efficiency and filter lifespan.

Some considerations for installation and long-term maintenance planning may include the following.

HVAC upgrades

HVAC systems are sometimes outdated, inefficient, or incompatible with MERV 16 technology.

System upgrades and custom installation plans may be necessary to achieve the maximum filtration capabilities and protection from airborne infections.

Energy management

Unlike MERV 13, MERV 16 systems do not require 100% ventilation to filter indoor air pollutants. This means that your HVAC system can be turned on and off as needed to save energy.

Reduced ventilation can also reduce your school’s carbon footprint while still achieving up to 95% filtration efficiency and protecting classrooms from outdoor air pollution (6).

Smart thermostats and other energy management systems can help your school program air filtration systems for use during school hours when students are in class.

Air quality monitoring and smart technology

Air quality monitoring coupled with smart technology, such as smart thermostats, can help automate filtration behavior with predetermined protocols:

  • HVAC Systems: Smart thermostats are programmed to keep HVAC on “Fan On” mode for clean air even when cooling or heating are off.
  • High-Capacity Stand-Alone Systems: Filtration systems are coupled with occupancy sensors or timers that can integrate with air quality monitoring to turn systems off and save energy when classrooms are empty.

3. Air quality verification and monitoring

Indoor air pollution in many schools, especially UFPs and PM2.5, has long resulted in poor student health outcomes and cognitive development (7) (8). These pollutants will likely remain a major threat.

Monitoring air quality is critical to ensuring that air filtration technologies are sufficiently providing clean air. Air quality data can also help demonstrate long-term improvements in connection with other school-wide data.

    A real-time public air quality dashboard displaying indoor and outdoor data to parents, teachers, and other school stakeholders can also demonstrate the value of clean air in real time. This data can be displayed either on public smart TV monitors or a live, customized air quality feed using air quality monitoring software.

    The benefits of clean air are extensive. Monitoring air quality can help schools show just how much reductions in air pollution can help improve health and academics.

    Numerous studies have already illustrated the very real health and academic consequences of airborne particulate matter for students with allergies and asthma, including (9) (10) (11):

    • a 2016 study suggesting that indoor pollen concentrations are directly linked to lower test scores
    • a 2017 study finding that students with asthma were more likely to miss school and experience disruptive anxiety symptoms about academic outcomes as a result of poor indoor air quality
    • a 2019 study indicating that school absences due to asthma can make academic outcomes progressively worse over time, especially for students in highly polluted urban areas

    4. Maintenance and renewal

    Clean Air Schools can display a customized placard that indicates to the public that your school meets stringent infection control and indoor air quality requirements (see Figure 2 for an example).


    Clean Air School plaque

    Figure 2: Example of Clean Air School wall plaque that can be displayed in public view as long as your school meets the technology and filter replacement requirements.

    As long as your school adequately maintains HVAC air filtration systems for maximum efficiency and replaces filters at recommended intervals, your school can continue to display your Clean Air School status to all parents, teachers, and stakeholders.

    Typical maintenance and renewal requirements include replacement of all air filtration systems approximately every 12 months or as needed. Other data that can affect your renewal requirements include:

    • specific installation setup
    • air quality sensor data
    • usage patterns (i.e., how long you use air filtration each day)

    The takeaway

    Clean air has become central to the conversation around safe classroom environments. But clean air also has many other benefits, helping schools to reduce harmful pollutants in classroom air, reduce absences, and increase student performance.

    Equal access to clean air can also help close the achievement gap across all schools.

    Expert help and customized solutions can help ensure that your school can access the most effective air filtration and be rewarded with the benefits of clean air.

    The number one air cleaning solution for your home.

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