Can quality air filtration in schools lead to better student well-being, higher achievement?

The importance of air filtration for schools has been magnified recently due to the spread of airbourne illnesses, but also because recent studies show how poor indoor air quality can affect test scores, cognition, problem-solving, and grades, and can cause chronic cardiovascular diseases. What can we do about air quality in educational facilities in Canada? In this article, we will answer that question as well as take a detailed look at air filtration systems options available for schools. 

A school hallway with lockers on both sides. A doorway is at the end of the hall and has sunlight coming in. The lockers are yellow and the floor is wood

Why is good indoor air quality important for schools? 

Indoor air quality and students’ capacity to learn and progress are inextricably linked. Poor indoor air quality can impair students’ ability to concentrate and think effectively. When air is polluted, students can feel symptoms such as headaches, and tiredness, and can experience respiratory disorders, making it harder for them to perform well in their studies.

According to research, poor indoor air quality can lead to decreased cognitive function and impaired concentration for students. This is due to the presence of pollutants such as volatile organic compounds (read more about VOCs), mould, PM2.5 and PM1, and allergens in the air. 

Air Pollution Can Lead to Lifelong Health Complications 

Schools that are located in areas with high levels of pollution bring in harmful particles from outdoor air entering classrooms and other areas of schools. Poor indoor air quality can lead to lifelong health complications such as respiratory diseases, cardiovascular issues, and even cancer. With the presence of indoor air pollution and the inhalation of fine particulate matter, PM2.5 and PM1, and toxic gases, cardiovascular disease and organ damage have been established. Also, exposure to polluted air over time can weaken the immune system, exacerbating health problems. 

Benefits of Air Filtration for Schools are supported in study after study

Several studies support the benefits of air filtration in schools. One study found that installing portable units with high-efficiency particulate air (HEPA) filters in classrooms can reduce absenteeism by up to 50%. Experiments show that HEPA filtration can greatly reduce levels of pollutants, airbourne viruses, and allergens, improve indoor air quality and create more comfortable, healthy spaces where students perform better. 

Professor Joseph Allen of Harvard University studied office workers exposed to various levels of carbon dioxide and VOCs and found that workers who were exposed to more CO2 and VOCs had decreased cognitive functioning scores. “What we saw were these striking, really quite dramatic impacts on decision-making performance, when all we did was make a few minor adjustments to the air quality in the building,” Allen said. “Importantly, this was not a study of unique, exotic conditions. It was a study of conditions that could be obtained in most buildings, if not all.” Source:

The Environmental Protection Agency (EPA) states, “Evidence that indoor air quality (IAQ) directly impacts health and student academic performance continues to mount…(this includes) levels of pollutants, humidity, temperature, etc. that impact the occupants’ health, comfort and ability to perform.” 

“Qualitative and quantitative evidence demonstrating the relationship between IAQ and human performance and productivity has become more robust. Studies demonstrate that improved IAQ increases productivity and improves the performance of mental tasks, such as concentration and recall in both adults and children…health, attendance, and academic performance can improve with increased maintenance.”


Another study concluded that doubling the ventilation rate from about 7.5 cubic feet per minute per person (CFM/person) to 15 CFM/person improved academic performance by about 8 percent. Source: Wargocki, P. and Wyon, D.: Research report on effects of HVAC on student performance. October 2006 ASHRAE Journal, 48: p. 22-28


  • Reduces absenteeism for students and staff
  • Reduces building deterioration and improves energy efficiency
  • Reduces outside air ventilation requirements
  • Adequate air filtration prevents the spread of communicable diseases
  • Prevents strained relationships resulting from poor indoor air quality
  • Promotes healthy environments for people with allergies and asthma
  • Reduces liabilities
  • Most importantly, helps to protect students – one of our most important investments in the future

Strategies for improving indoor air quality in schools

Proper ventilation and air filtration are essential for improving indoor air quality in schools. Building guidelines call for a minimum of 6 air changes per hour (ACH) for a classroom in use, but 20 AHU is recommended for optimal teacher, support staff, and student health.

Air filters should have a minimum rating of MERV-13-A to remove finer particles in the PM1 and PM2.5 range. A MERV-A rating ensures a maintained MERV performance and efficiency, not peak performance when the air filter is new. Filters should utilize the maximum depth available within the air handling unit (AHU). This allows for maximum media area, which leads to longer filter life and lower pressure drop.  In many cases, the air filtration system can be retrofitted to allow for the installation of deeper filters.  

A routine maintenance program is important for the upkeep of air handling units and ducts that are part of the school’s HVAC system. Regular maintenance ensures that all the components are clear of debris and do not become overwhelmed by extreme weather. The better an HVAC system is maintained, the longer it will last and remain highly efficient. 

Air quality monitors can play a big role in improving indoor air quality and ensuring a minimally acceptable level of air quality is maintained. When using VFD-controlled fans, maintenance staff can A/B test fan speed at various times of the day, using monitor readings, in real-time. This allows schools to achieve great air quality while saving energy at the same time. 

Building design affects air quality in schools

Building design is also very important as it can maximize ventilation and airflow. E.g. making corridors wider to allow more airflow and less student traffic congestion. Crowding can reduce air circulation in schools. Also, too much furniture or other equipment and clutter can impede airflow in schools. It is advisable to reduce clutter as much as possible to avoid blocking vents and airflow.  Read more about air filtration system design 

Designing schools with all of this in mind can significantly contribute to improving indoor air quality and the overall health and well-being of students, teachers, administrators, and staff. Read MORE 

Camfil air quality in schools expert, Rob Kealey states, “A lot of facilities are just set up to have a 2-inch deep pleated filter, however, in many of the newer schools, we’ll see larger air handling units that can accommodate proper final filters such as a MERV-14-A  filter, which we would certainly recommend using for cleaner air. Sometimes there are novel ways to adapt the existing 2-inch hardware to accept a 4-inch deep air filter, but there are limits. Other times, you’re looking at fairly substantial hardware changes, which can be costly.”

He continues, “Given the widespread problems associated with air quality, a lot of school boards are doing upgrades to their HVAC system to accommodate higher-quality final filters. A bag filter that is 22 inches deep or a v-bank filter that has very small pleats, sometimes referred to as a mini-pleat that resembles a HEPA filter, is a good choice. The greater media reduces restriction or the static pressure on the filter.” 

Installation and Maintenance of Air Filtration Systems in Schools

When planning and installing air filtration systems in schools, it is important to first do a needs assessment to determine the unique requirements of each educational institution. Speaking with an air filtration expert at the design phase or construction phase can help institutions choose the most efficient system within a given budget. 

The installation phase of the process is very important because if your system is not installed by skilled HVAC technicians experienced in properly dealing with gaps and openings in the air handling unit (AHU), you may not get optimal performance and energy savings. 

Maintenance includes: 

  • Cleaning of ducts, vents, coils, and other components regularly to eliminate contaminants that can affect air quality and equipment longevity
  • Inspection of the air filtration system at a scheduled time using meters and sensors to ensure the proper functioning of the system for optimal air quality and longevity
  • Filter replacement should be performed promptly when pressure drop, based on longevity or energy-savings setpoint has been reached. Replacement schedules can be established with the help of an air filter expert who can analyze conditions such as usage patterns and surrounding environments

Air filtration system design for schools

Building and room size, layout of halls and gyms, population of the school, and air quality of the surrounding areas are all important considerations when designing air filtration systems for educational institutions. 

It is also important to determine what the HVAC system’s capacity is. For example, many HVAC systems cannot handle high-MERV-rated air filters such as a MERV-14 due to system capacity limits. Designs should incorporate engineering best practices for educational facilities. 

Procurement of air filtration equipment 

Procuring filter housings and/or frames along with the required filters from a leading supplier of air filtration equipment gives you peace of mind that you will be getting what you pay for. Also, air filtration equipment experts can give you solid advice in consultations that can create the most efficient system that can save your institution considerable money over five to ten years, while at the same time offering you the best air quality possible. Also, air filtration design experts can guide you through industry best practices and government guidelines. 

What Are the Best Air Filters for Schools? 

Indoor pollution sources produce both gaseous pollutants (including VOCs) and particulate matter, which means that optimizing air quality in schools will involve using both activated carbon filters and mechanical filters (ideally HEPA filters and MERV-A-rated filters). 

Types of Air Filters for Schools

There are many different types of air filters for schools, the type that is best for your school will depend on several factors. 

Some of the most common types of air filters for schools are:

  • Portable air cleaners utilizing high-efficiency particulate air (HEPA) filters are designed to remove tiny particles from the air, making them very useful inside classrooms when IAQ problems persist. An advantage of using portable HEPA filtration units is that they can be run constantly when the classroom is in use, increasing the number of air changes per hour in the room, and dramatically improving indoor air quality.   
  • Molecular air filters such as activated carbon filters are effective at removing a range of gaseous contaminants from the air, including volatile organic compounds (VOCs), smoke, toxic gases, and odours by using the adsorption principle. Adsorption takes place when gas molecules cling to the surface of air filter media. Chemicals, toxic gases and odours can be effectively removed using molecular air filters. In an educational setting, using molecular air filtration removes pollutants that are released by off-gassing furniture and other equipment.
  • Mechanical air filters use mechanical principles (not electrostatic) to capture particles in filter media. This method of filtration maintains a MERV rating throughout the life of the filter. An ASHRAE Appendix “J” test report will confirm if the filters use mechanical filtration as the MERV and MERV-A ratings will be the same. For example, a MERV rating that is an actual rating in all situations, not a ‘best case scenario rating.’ 
  • Electrostatic filters work by using an electrostatic charge imparted during manufacture to enhance the effectiveness of the large-diameter fibres used in these types of filters. Due to their ineffective mechanical particle collection, electrostatic air filters may not provide enough protection for building occupants. With time, they may become less effective as the electrostatic charge dissipates. 

In its air filter testing standard, the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) acknowledges this problem. The size of the pollutants that are of concern should be taken into consideration while choosing filters, such as the crucial range of 0.3 microns to 0.7 microns which are lung-damaging particles. Most consumers anticipate that a filter with a MERV 14 efficiency will still be as effective after three, six, or twelve months. However, electrostatic air filters will become less effective with time, and this can lead to potential health problems. ASHRAE developed standard 52.2 Appendix “J” to ensure that the filters selected have matching MERV and MERV-A values.

Electronic air filters work by attracting negatively charged airborne particles to positively charged metallic plates using a high-voltage electrical field. They use electrical charges to remove airborne particles from the air. Larger particles are collected on these plates as air travels through a tiny area between them.

Portable HEPA filters are some of the most effective air filters available. They can remove 99.97% of airborne particles at 0.3 microns, making them ideal for trapping pollen, dust, and other allergens. In a perfect world, all HVAC units in schools would have HEPA filtration, however, this is not possible as HEPA filters are costly or can place too much of a strain on some HVAC systems. 

What government regulations or legislation exists regarding air filtration for schools? 

There are no federal regulations or legislation for air filtration in schools. However, Health Canada provides guidelines and recommendations for air quality in schools. Best practices come from manufacturers and engineers. 

For Canadian Government guidelines (not specific to schools) for indoor environments such as public buildings see:

Industry standards and best practices for air filtration in schools

The Canadian Centre for Occupational Health and Safety (CCOHS) provides guidelines on indoor air quality in Canadian buildings. CCOHS states, “Many Canadian jurisdictions do not have specific legislation that deals with indoor air quality issues in non-industrial workplaces. In the absence of such legislation, the “general duty clause” applies. This clause, common to all Canadian occupational health and safety legislation, states that an employer must provide a safe and healthy workplace.” Educational institutions are employers of teachers and support staff and must ensure their safety at work and by extension, it affects the well-being of students.

There are ventilation and air filtration requirements that apply to indoor air in occupational health and safety legislation, as well as building codes or other standards-setting organizations such as the Canadian Standards Association (CSA) Group, and the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). They set standards for IAQ such as the minimum air changes per hour for a classroom and the types of air filters required for different scenarios. 

Frequently Asked Questions (FAQs) About Air Quality in Canadian Schools

How often should air filters be changed in schools? 

It depends on the amount of media, the quality and type of the media, hours of operation of schools, and contamination levels. Pressure gauges that measure the pressure differential between the front and backside of an air filter, NOT visual inspection, should be used in determining the load on a filter.

What is indoor air quality (IAQ) and why is it important for schools in Canada?

Indoor air quality (IAQ) refers to the quality of the air inside buildings or facilities. Adequate indoor air quality for schools in Canada is important because students, teachers, and support staff spend a significant amount of time inside buildings. Good indoor air quality leads to better health and less communicable disease transmission. It has also been correlated to higher brain function, higher test scores, less absenteeism, and general well-being.  

What are the common sources of indoor air pollutants in Canadian schools?

Common sources of indoor air pollutants in Canadian schools include mould, dust, allergens, volatile organic compounds (VOCs)—from cleaning products, furniture and building materials— as well as outdoor pollutants that find their way inside through doors, windows, and garages, such as smog from vehicles, and factory emissions.

How can poor indoor air quality affect students’ health and performance?

Inadequate Indoor Air Quality (IAQ) can result in health complications such as breathing difficulties, allergies, and diminished cognitive abilities. This can cause students to have trouble focusing, retaining information, and engaging in academic activities.

What are some strategies for improving indoor air quality in Canadian schools?

Schools can improve indoor air quality in classrooms by ensuring proper ventilation, using air quality monitors, regularly maintaining HVAC systems, using low VOC furniture and materials, repairing leaks promptly, and keeping the environment clean.

  • Increasing ventilation: Outdoor air must come into all buildings according to ASHRAE standards and building codes, to dilute harmful particles and bring in oxygen. This can be achieved by increasing the amount of outdoor air or improving the filtration level that is brought into the building through the ventilation system
  • Use high-quality air filters that effectively remove particulate matter such as a MERV-13-A filter, as well as activated-carbon filters which remove gaseous pollutants, VOCs, odours, and ozone from the air
  • Prevent overcrowding in classrooms, hallways, cafeterias, assembly halls, lecture halls, and gymnasiums. This can be achieved by reducing the number of students in each classroom or other facility, or by increasing the size of the rooms or hallways
  • Portable air cleaners can be used in areas where overcrowding is inevitable due to budget or building design constraints. These devices can help remove pollutants from the air and dramatically improve indoor air quality in a localized area such as a small classroom

Are there specific regulations or guidelines for indoor air quality in schools in Canada?

Health Canada provides guidelines for indoor air quality in schools. Additionally, provinces like Ontario and British Columbia have specific regulations addressing IAQ in educational institutions. For the most part, in Canada federally, there are no actual regulations, just best practices and guidelines. 

How often should schools in Canada test their indoor air quality?

It’s recommended that schools conduct IAQ testing regularly. Once a month may not be enough to deal with issues that arise such as dealing with smoke from wildfires or industrial pollution which may spike at different times of the year. Testing should also be done when students feel symptoms of poor IAQ, such as dizziness, fatigue, or breathing issues, or after building renovations. Air quality sensors placed around the school can be very helpful.

What role do HVAC systems play in maintaining good indoor air quality in schools?

HVAC systems are central to maintaining good IAQ in schools. They regulate humidity, keeping it between desired lower and upper limits (relative humidity at 30-50%), to keep airbourne viruses at bay, as well as to protect equipment. They also regulate temperature, keeping the indoor environment comfortable. Finally, HVAC systems exchange air from outdoors to indoors and vice versa. 

What steps can schools take to prevent mould growth and moisture issues, especially in humid Canadian climates?

Schools can take the following steps to prevent mould growth and moisture issues according to Health Canada and the EPA:

  • Relative humidity should be kept between 30% and 50%
  • Use an air conditioner or dehumidifier to lower the humidity
  • Ventilate washrooms, gym change rooms, and other areas that produce moisture 
  • Use a hygrometer to monitor humidity levels
  • Within 24 hours of a spill or leak, clean and dry wet or damp building materials and furniture to avoid mould issues
  • Properly ventilate facilities such as cafeterias when cleaning and cooking, exhaust fans should be used

Are there IAQ certifications or programs that Canadian schools can participate in?

Yes, “Indoor Air Quality Certification” is offered by the Canada Green Building Council (CaGBC) as well as from other organizations such as the BOMAbest program Read More on Building Certification in Canada

Which products does Camfil recommend for air filtration in schools?

Camfil AQ13 -A high-capacity pleated panel filter that complies with MERV 13 requirements with twice the service life as other competitive MERV 13 pleats. It is compatible with existing air handling units in most educational institutions in Canada. 

30/30 Dual 9 – Guaranteed to last longer. The 30/30 Dual 9 offers true MERV 9A maintained efficiency. ISO 16890 ePM10-55%. Guaranteed 9 – 12-month service-life. Saves energy. 

Camfil CityPleat – A combination filter that targets gaseous pollutants and particulate matter with a filter depth of two or four inches, making it ideal for a range of commercial and residential applications. 

To consult with an air filtration expert who specializes in schools, or for additional information, please use this contact form and a Camfil air filtration expert will help with questions and requests.

About Camfil Canada Clean Air Solutions

For 60 years, Camfil has been helping people breathe cleaner air. As a leading manufacturer of premium clean air solutions, we provide commercial and industrial systems for air filtration and air pollution control that improve worker and equipment productivity, minimize energy use, and benefit human health and the environment. Read more about Camfil Canada


Environmental Protection Agency 

University of Toronto 

Health Canada

American Society of Heating Refrigerating and Air-conditioning Engineers (ASHRAE)

Canadian Centre for Occupational Health and Safety

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Shendell, D. G., R. Prill, et al. 2004. “Associations between classroom CO2 concentrations and student attendance in Washington and Idaho.” Indoor Air 14(5): 331-41. 

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