A Guide to Indoor Air Quality
& Air Filtration

In this guide, we’ll explore the harmful pollutants that may be around you, how you can improve indoor air quality, and the air filtration systems that are available to consumers.

Outdoor air pollution has gotten a lot of attention. Industrial and automotive emissions, smog, and gases such as ozone can be harmful. But did you know indoor air problems can be just as bad, or worse? Indoor air pollutants include particles just nanometers in size, both organic and inorganic, and gases emitted from common building materials and consumer products, among many other contaminants.

Chapter 1
Introduction to Air Quality

Indoor air quality, or IAQ, refers to the air quality inside a building or structure. It can have a big impact on the health, comfort, and well-being of occupants, whether in residential, educational, or office settings. The effects of indoor pollutants can be felt immediately, as in the case of allergies, or years later in the form of serious respiratory issues, heart disease, and cancer.

It’s as important to have fresh indoor air as it is to have clean outdoor air. Proper ventilation and air cleaning and filtration help as most of us spend a lot of time indoors. Without it, the levels of indoor pollutants can reach unhealthy levels. Some pollutants are unavoidable. A means to filter them and transport them outside is therefore necessary. Also, many pollutants can become more concentrated if the temperature and humidity become high enough.

Indoor contaminants can affect people in any type of building if the appropriate measures aren’t taken. Some of the most common places of concern are:

  • Homes: Causes of IAQ issues in the home include poor ventilation, often originated from ductwork issues. Pollutants often build up from combustion sources such as oil, gas, coal, or wood burning appliances as well as certain types of building materials, insulation, and cleaning products. These can be dispersed and released outside with good ventilation systems. Many modern homes are effectively sealed from outdoor air. However, without enough outdoor air, indoor pollutants can accumulate to unsafe levels. Weather conditions can also prevent outside air from reaching inside a home. Air naturally enters a house via infiltration through building openings, joints, and cracks; open windows and doors (natural ventilation); and mechanical ventilation systems. An important aspect of ventilation systems is exchange rate; an HVAC system with a low air exchange rate can increase pollutant levels if infiltration or natural ventilation are limited.
  • Schools: An environment where children should learn and be safe, schools are susceptible to indoor air quality problems. School-age asthma is widespread, affecting nearly 1 in 13 children, according to the U.S. Environmental Protection Agency (EPA). This is a leading cause of absenteeism due to chronic illness. Dust mites, mold, and exposure to allergens from pests are though to contribute to the problem, as are fumes from the diesel exhaust systems of school buses. The effects of indoor pollutants impact the comfort and performance of students, teachers, and other staff. Certain contaminants can impede a student’s ability to learn and develop. Poor IAQ has other potential effects, including increased potential for school closings, strained relationships between parents and school staff and administrators, negative publicity, and possible liability. It can also reduce the efficiency of a facility’s physical plant/equipment and accelerate wear, leading to higher expenses down the line.
  • Offices: Indoor air quality is often a problem in office buildings. These larger buildings are all too often improperly ventilated, so airborne particles, viruses, and allergy-causing substances aren’t adequately removed. It’s harder to avoid pollution and the associated health problems because there’s less control over air quality in your office. Office and building personnel, design engineers, contractors, and architects are responsible for the systems that maintain air quality in buildings. The problem has become so widespread that the American Society of Heating, Refrigeration and Air Conditioning (ASHRAE) has developed a guide of its own, providing reference materials on the design, construction, and commissioning of air quality systems. The EPA has found that indoor environments are often more polluted than outside. Given that most Americans spend up to 90% of their working hours indoors, the risks include not only health problems, but also lost productivity and an increased need for medical care.

Chapter 2
Causes of Indoor Air Problems

nx-heatergraphics_airpollutants

There are many sources of indoor air pollution, making it even more important to address air quality and air filtration in any building. The environment is filled with health risks that need to be dealt with.

Top Environmental Health Risks

Indoor air pollution is among the top environmental risks; given how much time people spend indoors, it’s important to be aware of common pollutants that can affect your health. The leading environmental health hazards, including respirable particles, mold, chemical emissions, radon, and combustion gases, are present indoors. Other potential indoor hazards include radon and pesticides, while tobacco smoke poses a range of health risks as well. In fact, some pollutants may be two to five times more concentrated indoors than in outdoor air, according to the EPA.

Pollutants and Health Impacts

The most common pollutants in homes, schools, and offices that pose serious health risks include:

  • Radon: A naturally occurring radioactive gas in soil, radon can get inside through any crack or floor/wall opening near the ground. Although radon can be found in drinking water, in the air it is the leading cause of lung cancer in nonsmokers. It is also the second leading cause of the disease overall.
  • Secondhand Smoke: Smoke from tobacco burning products can affect the health of nonsmokers, especially children. Secondhand smoke exacerbates asthma and has been found to increase the risk of Sudden Infant Death Syndrome and ear infections. It is released by cigarettes, cigars, and pipes as well as when smokers exhale. The EPA classifieds secondhand smoke as a Group A carcinogen.
  • Combustion Pollutants: Gases and particles that originate from burning materials in gas and wood-burning stoves, water heaters, dryers, fireplaces, and chimneys. Common types include carbon monoxide, which impairs the body’s ability to deliver oxygen (and is colorless and odorless), and nitrogen dioxide, also an undetectable gas that causes eye/nose/throat irritation and respiratory infection.
  • Volatile Organic Compounds (VOCs): Released during evaporation or storage, VOCs can originate from common household cleaning products, including aerosol sprays, air fresheners, chlorine bleach, detergent, rug and upholstery cleaners, and paints and varnishes. Symptoms of exposure include eye, nose, and throat irritation as well as headaches and nausea. Exposure can also cause liver, kidney, and neurological damage and even cancer.
  • Lead: Is most often present in old paint and becomes airborne when this is scraped or sanded, but can also originate from contaminated soil and drinking water. Lead is particularly harmful to babies and young children who are susceptible to neurological damage and often put their hands in their mouths after handling lead-containing materials. It may also be inhaled as dust or ingested by playing with toys coated with lead paint.
  • Asthma Triggers: Dust mites, pet dander, and mold growing on shower curtains, blankets, stuffed animals, and other surfaces can trigger asthma. Other asthma triggers include secondhand smoke, various air pollutants, and even some types of food. Asthma can present as a cough, wheezing, and chest tightness. In severe cases it can be life-threatening. Control measures include medicine or reduction of triggers in the air.
  • Mold: Mold spores are naturally present in the air and grow on any moist surface. If you inhale mold, it can cause runny nose, sneezing, red eyes, and other symptoms of hay fever. Even touching it can cause a rash. Proper moisture control can curb the growth of mold. Extremely moist conditions or a flood, whether caused by a plumbing problem or natural event, increase your risk.
  • Formaldehyde: A volatile organic compound found in building materials, air cleaners, wood products, and as a byproduct of various other gaseous pollutants. Formaldehyde has a strong smell and can be extremely irritating to respiratory linings. It can also adversely affect the nervous system, trigger asthma (especially in kids), and is a carcinogen.
  • Pesticides: Have active ingredients that control pests, including microorganisms like bacteria, viruses, and fungi. Many pesticide products also contain inert ingredients that may be toxic. These VOCs can help active ingredients penetrate a leaf surface, prevent the product from caking or foaming, or extend shelf life. They can trigger a range of adverse acute and chronic health effects in non-targeted humans and animals.
  • Asbestos: A naturally occurring mineral fiber, asbestos is found in building materials such as ceiling and floor tiles, cement, and roofing shingles as well as in heat-resistant fabrics, packaging, coatings, and automobile brakes. Home remodeling activities most often cause it to become airborne. If inhaled, it can cause a scarring of the lungs, called asbestosis, which can lead to breathing problems, heart failure, and lung cancer.

Pollution and Ventilation

Proper ventilation can reduce the concentration of indoor air pollutants in a home or business. However, a ventilating system must provide consistent operation. While an improperly adjusted gas stove may emit carbon monoxide while it is on, other sources can emit pollutants continuously. These include building materials, air fresheners, and furnaces. Solvents used for cleaning, hobbies, and in paint strippers and pesticides can remain in the air for a long time.

It’s therefore essential to address ventilation whether you live in a:

  • House: Whether air enters through openings in exterior surfaces, through doors or windows, or through mechanical systems, a house requires the ventilating of indoor and outdoor air. When outdoor air can effectively move in and out, it can disperse pollutants and improve indoor air quality. Higher air exchange rates are more conducive to reducing pollutant levels.
  • Apartment: Occupants rely more on building management to follow EPA and NIOSH guidelines for building air quality. Nonetheless, they can take actions such as removing pollution sources, unblocking an air supply vent, changing their habits, and even installing air cleaning devices. Opening a window occasionally can also help.

Chapter 3
How to Improve Indoor Air Quality

Whether you or someone in your home has symptoms or are concerned about indoor pollution, there are steps to take to improve air quality. In order to control sources of pollution, you must:

Identify Specific Air Quality Problems

If symptoms develop after you move into a new home, remodel or refurnish an existing home, or use a pesticide treatment, there may be a potential air quality problem. You can try to identify potential sources of pollution from the air, furnishings, or specific products. Although this may not verify such sources are problematic, it is an important step in air quality assessment. 

Also, examine your activities to determine if they are contributing to indoor air pollution. Ventilation problems can also contribute to air quality issues. If the air is stuffy, there are musty odors, moisture is condensing on windows and walls, items are moldy, or HVAC equipment is dirty, your home may require more ventilation.

Measure Pollutant Levels

If you’ve identified specific pollutants and/or sources, it’s time to measure them. Whether you notice health symptoms or signs that ventilation is insufficient, contact a professional or local health department for assistance. They have experience in measuring pollutants, access to the proper equipment, and knowledge of EPA guidelines in conducting measurements.

Radon, formaldehyde, and various VOCs can be measured. A VOC sensor picks up traces of pollutants and tells you how much of a certain compound is present. The results can tell you if the level is above recognized guidelines and presents a health risk. Due to a lack of IAQ standards, it is best to consult with a health agency to determine whether identified indoor pollutants directly caused an illness.

Weatherize Your Home

Weatherizing refers to steps taken to reduce energy consumption related to heating and cooling a home. It usually does not add new pollutants, except in rare cases of caulking that emits VOCs. Installing weather stripping, blown-in wall insulation, and storm windows can prevent outdoor air from infiltrating, per federal recommendations. 

When weatherizing a home, indoor air pollutants can become more concentrated. It’s therefore important to recognize issues such as air becoming stuffier, moisture condensing on cold surfaces, or signs of inadequate ventilation once you’ve begun weatherizing a home. If these occur or you find mold or mildew, correct them before continuing your weatherization efforts.

Change Filters Regularly

Air filtration can dramatically improve indoor air quality. But whether you install a whole house or single room filtration system, it is important to maintain the filter. A dirty filter can contribute to pollution and even impede air flow, especially in ductwork.

If you have a central air conditioning system, install a filter with a Minimum Efficiency Reporting Value (MERV) of at least 10 (out of 16). This measures how efficient it is at trapping airborne particles. To maximize the efficiency of a filter:

  • Make sure it is installed correctly
  • Clean out dust buildup monthly
  • Replace it every three months
  • Operate the central air system with a fan on
  • Install a ventilation system separately from forced air heating when remodeling

Air Duct Cleaning

Addressing air quality goes beyond cleaning and replacing filters. It must also include cleaning your air ducts and associated components, including grilles, registers, and interior surfaces. If you’re not comfortable cleaning your ducts, consult a professional. They know how to access each unique system and also check for leaks and other problems.

Common problems include duct clogs due to dust and debris as well as infestations by insects and other pests. Also, mold can grow on interior surfaces of sheet metal and cause air quality problems.

Cleaning HVAC ducts sometimes requires using specialized equipment to loosen contaminants. A technician may use compressed air, specialized brushes, or vacuums. Fine particles can be removed using continuous negative pressure, which prevents airborne materials from entering your living space. Sanitizers, disinfectants, and deodorizers may also be used on surfaces within your HVAC system.

Cleaning your HVAC ducts regularly can:

  • Improve Indoor Air Quality: Every contaminant in your home is sucked into the HVAC system and recirculated several times per day. Cleaning ducts can remove these contaminants and mitigate various health issues.
  • Save Energy: Up to 40% of the energy used for heating and cooling homes is wasted, mainly due to contaminated air ducts.1 Dirt forces the system to work harder, so duct cleaning can reduce your energy bill.
  • Extend HVAC Longevity: New HVAC systems cost thousands of dollars. If you don’t want to replace your system yet, air duct cleaning and other maintenance can add years to its life, avoiding unnecessary costs.
Team tackling dirty duct

Air ducts should be cleaned every three to five years, according to the National Air Duct Cleaners Association. Action should be taken sooner if occupants of your home have allergic reactions or other symptoms. Always clean the duct system when you move into a new home and/or if it’s been three years since the previous owner serviced the ducts.

Other Ways to Improve Indoor Air Quality

Not all air quality improvements in your home require extensive work. Effective strategies, depending on the problem you have, include:

  • Adjusting Humidity: There is a correlation between humidity levels and some indoor air pollutants, especially mold. If indoor humidity is above 50%, there’s a higher risk of mold growth. It should be between 30% and 50%. If your home is too humid, open the windows or turn on the air conditioner. Humidity can be increased if your home is dry by using a vaporizer or humidifier, which can also be adjusted to raise or lower humidity levels.
  • Ventilation Improvements: The simplest measures include opening windows or adding fans, which can ventilate VOCs from painting or remodeling. Exhausting air from a kitchen can help prevent particles and gases from becoming highly concentrated, while venting a bathroom can reduce water vapor. However, it’s important to ensure air being pulled into the room is dry and clean. Air cleaning is often used with ventilation. Not all air cleaners provide effective ventilation, as not all models work for all pollutants. For example, table top units may not mitigate strong sources of pollution. In fact, air cleaning may be ineffective when significant sources of air pollution are present.
  • Install an Air Cleaner/Purification/Filtration System: Air cleaning devices can be installed when ventilation is limited. Some types, including mechanical air filters (through capture) and electronic air cleaners (use electrostatic precipitators to leverage ionization and electrostatic attraction), can remove airborne particles. Gas-phase air filters use a sorbent to remove gases and odors from air that passes through them.

Other air cleaners use UV radiation for pollutant destruction. These include UVGI cleaners, which use UV lamps to destroy biological pollutants in the air and on HVAC surfaces. Not designed to remove particulates, PCO cleaners use UV light and a catalyst that reacts with light to convert gases into harmless substances. Ozone generators, on the other hand, generate ozone (via UV light or electricity), but don’t remove most indoor air pollutants (and can cause lung irritation).

Different Types of Air Filters Infographic

For homes not equipped with a central air conditioning system, portable air cleaners may be used to remove particulate matter. Otherwise, effective air purification and filtration may be achieved with an in-duct particle remover, which can be a flat air filter or panel air filter (MERV 1 to 4), pleated filter/extended surface filter (MERV 5 to 13), and even higher efficiency filters (MERV 14 to 16). 

When using air cleaners, it’s important to consider installation requirements, costs (including cleaning/replacing filters and electrical usage), and whether the device provides odor removal. Ion generators can leave deposits on surfaces from particles they attract with an electrical charge. With portable air cleaners, noise may be an issue, while those with a fan typically work more effectively.

Chapter 4
Tips to Help Control Indoor Pollutants

If your home has indoor air pollution, it can be controlled. To improve IAQ, you can:

  • Test for radon with do-it-yourself kits (check for a label that says “Meets EPA Requirements) or by hiring a trained contractor. If radiation has been found in the air, have the radiation in your water supply measured by a certified lab, which can also determine how to address the problem.
  • Avoid or discourage smoking. Tobacco smoke has over 4,000 compounds, 40 of which are carcinogenic. To reduce the risk to smokers and nonsmokers indoors, ask a smoker to go outdoors, or increase ventilation to limit exposure to environmental tobacco smoke. Opening windows or installing exhaust fans can help remove smoke, but can increase energy costs. Increased risks associated with smoking include:
    • The presence of radon. When combined with smoke, the health risks increase.
    • Children, infants, and toddlers. Are more susceptible to health risks from passive smoking.
  • Install exhaust fans in kitchens and bathrooms as well as for clothes dryers, which are generally quiet and can reduce moisture and organic pollutants vaporized from hot water. Also ventilate the attic and crawl space to lower humidity and prevent water condensation. Dehumidifiers can be used in basements to lower humidity there.
  • Reduce exposure to biological contaminants by properly cleaning cool mist or ultrasonic humidifiers, thoroughly cleaning and drying water-damaged carpets, and regularly cleaning your home to reduce pollen levels, animal dander, dust mites, and other allergens.
  • If you use a kerosene or gas space heater, follow the manufacturer’s recommendations for adjusting the appliance and using the proper fuel. A yellow-tipped flame may mean increased pollutant emissions. Exhaust fans should be used over gas cooking stoves and ranges and, if using a wood stove, make sure it is properly sized and EPA certified.
  • If using household products with chemicals, follow the label instructions and heed any warnings. For example, if it suggests using the product in a well-ventilated area, use it outdoors, where there is an exhaust fan, or near an open window. Old, unneeded, or partially full chemical containers should be discarded. Products with methylene chloride, benzene, perchloroethylene, and formaldehyde are especially high risk.
  • Pesticides should be used according to the directions on the label. They should only be mixed or diluted outdoors or in well-ventilated areas and disposed of per the manufacturer’s or hazardous waste collector’s guidelines. If available, choose a nonchemical method of pest control.
  • If asbestos is found, leave it alone if the material is in good condition. If there are asbestos-containing materials in your home, do not cut, rip, or sand them and throw out any damaged/worn asbestos gloves, ironing board covers, or stove-top pads. If you find any asbestos material that’s slightly damaged, or if any house remodeling will disturb it, call a professional contractor.
  • If you suspect lead is present, mop floors and wipe window ledges, cribs, and other surfaces with a dishwasher detergent. Other protective measures include washing toys and stuffed animals, and ensuring children wash their hands, frequently. Don’t burn painted wood or remove lead paint yourself. Also, make sure to wipe your shoes on a door mat if you work in construction, demolition, or wherever lead dust is present.
  • Choosing hard-surface flooring instead of carpeting can reduce the materials available for pet dander, mold spores, dirt, and dust to accumulate. If you install a carpet, unroll and air it out in a well-ventilated area, and choose one with low-emitting adhesives. Open windows and turn on fans/mechanical ventilation equipment for 48 to 72 hours after installation.2 And, remember to clean it often.

The performance characteristics of your HVAC system impact the level of indoor pollutants as well. With proper air filtration and maintenance, you can reduce the amount of dust, pollen, mold, and bacterial spores in the environment. What is in your air ducts circulates through your home’s air. If you don’t have the equipment or experience, contact a professional for routine maintenance that can make your indoor air healthier.

Chapter 5
Other Places Poor Indoor Air Quality Can Be Found/Best Practices

Following best practices can address poor air quality in places people spend a lot of time indoors—such as homes, schools, and office buildings.

Remodeling Old Homes and Building New Homes

Remodeling a home can pose a variety of air quality risks. Even fixing damaged paint can be hazardous, but a fresh coat isn’t always the answer. Condensation, leaks, and structural damage may have caused the damage, so it’s important to identify and correct any underlying causes. 

If your home was built before 1978, it’s best to assume it has lead-based paint and to take appropriate precautions. Contact an asbestos professional if the material is present and the project requires working near it. An asbestos removal specialist has the proper tools and equipment to deal with the issue safely before you move forward.

If you find mold during a renovation, clean it up and be sure to remove excess water and moisture, where it can continue growing. Detergent and water can be used to wash mold off hard surfaces. Check for leaks in plumbing or other sources. These should be fixed, while moldy carpet, ceiling tiles, and other absorbent materials should be immediately replaced. 

When working in potentially dusty areas, use a water mist to wet surfaces down before scraping or sanding, or place a barrier around the work area. Use fans and other ventilation to remove pollutants and prevent them from spreading to other rooms. When using paints, sealants, or adhesives, check Material Safety Data Sheets for information such as toxicity, health effects, and how to deal with exposure. Storage, disposal, protective equipment, and spill leak procedures are typically included as well.

Tips for New Construction

A structure can be built such that wooden building materials aren’t in contact with the soil. This prevents termites from accessing the structure and avoids requiring pesticides to address a termite problem. Solid wood products can prevent indoor air quality problems, as can exterior grade pressed wood products (for floors, walls, and cabinetry) with phenol-formaldehyde.

During construction, add proper drainage and sealing to foundations. More moisture can enter from here than any activities in the home. Mechanical ventilations systems, installed from the start, can consistently deliver outdoor air to maintain IAQ. Also make sure furnaces, fireplaces, and heaters are both well-ventilated and get enough supply air. You can prevent backdrafting of particles and gases, especially from a chimney or flue.

Schools

Air quality is a concern at elementary and secondary schools, where 20% of the U.S. population spends their days, and in preschools, day-care centers, colleges, and universities. There are also about four times as many occupants within the same amount of floor space as an office building. This means more people are exposed to pollutants; plus, even the carbon dioxide they exhale can contribute to air pollution.

School indoor air pollution can affect not only students but also teachers, administrators, parents, and facility managers. The EPA created the Indoor Air Quality Tools for Schools Program to help facilities assess and improve IAQ and pollutant sources such as kitchens, locker rooms, and cleaning storage areas.

A school air quality inspection often finds issues with design, construction, operation, and maintenance. Problems often arise in combinations such as a broken fan belt preventing outdoor air from venting inside (and diluting the pollutants) or air leakage through the ceiling or roof. Other issues include using housekeeping products at higher strengths than recommended and storing them in utility closets connected to return air ducts.

As in homes, good ventilation and proper storage can protect school building occupants. Local exhaust can best address specific problem areas while air filtration is effective at mitigating IAQ problems. Ventilation and filtration are important because pollutants can be distributed within an individual room, to adjacent rooms, between upper and lower levels, and through HVAC ducts. Ensuring healthy air in school buildings is a complex process. In addition to EPA guidance, helpful tools include:

  • Indoor Air Quality Self-Inspection Checklist: This checklist from the National Institute of Occupational Safety and Health (NIOSH) covers a variety of general recommendations that school districts can follow.
  • School Advanced Ventilation Engineering Software (SAVES): A free software tool that can be used by school officials, architects, and engineers to make school buildings healthier and more energy efficient. 

Office Buildings

Common IAQ issues in office buildings include poor ventilation, a lack of temperature/humidity control, and contamination from construction and renovation activities, cleaning supplies, and airborne chemicals. Unfortunately, the Occupational Safety and Health Administration (OSHA) does not have IAQ standards, but it does have standards pertaining to ventilation and some common air contaminants. Facilities can also follow indoor air quality regulations of states such as California, which covers:

  • The complaint and referral process
  • Complaint classification (HVAC system, particulates, thermal stress, etc.)
  • IAQ investigation procedures
  • Citation procedures
  • Specific violations

IAQ problems can’t be diagnosed with one single test. Facility managers should check for leaks, water damage, odors, dirt, pest droppings, and issues with ventilation, heating, and air condition systems. Employees can provide helpful information such as experiencing symptoms only at work and if they occur at certain locations or times of the day. Identifying whether they began during a renovation or construction project can be helpful as well.

In addition, OSHA has put forth Workers’ Rights, stating workers have a right to:

  • Safe working conditions
  • Information and training on hazards/prevention
  • Access to records on work-related injuries/illnesses
  • File a complaint to prompt an OSHA inspection
  • Report their concerns without retaliation

Office managers can improve indoor air quality by communicating with building management on potential issues. They can also:

  • Place office furniture and equipment so it doesn’t interfere with air circulation and pollution removal. 
  • Coordinate with building managers in the design, operation, and maintenance of the ventilation system
  • Consult with building management and contractors before a remodeling or renovation project.
  • Enforce a smoking policy that protects occupants against exposure to smoke.
  • Consider indoor air quality when making purchasing decisions

Employees are responsible for maintaining air quality as well. Compliance with non-smoking policies, proper food storage and disposal of garbage, and avoiding blocking air vents or grilles can help maintain air quality. You can also avoid bringing items inside that could release harmful substances. It’s also important to promptly notify a building/facility manger if an IAQ problem is suspected.

Chapter 6
Buyers Guide to Air Filtration Systems

Indoor air pollution is one of the top environmental risks to humans. Ventilation is an effective way to control IAQ, but it is sometimes limited by high levels of contaminants or weather conditions. However, air cleaning devices remove pollutants directly from indoor air. Rather than vent it to the outside, these systems just filter whatever air passes through them. 

Air passes directly through an air filter. In the process, materials are trapped by the medium so air flowing outward has fewer contaminants. Common filter elements include carbon and fiberglass. When shopping around for an air filter or air filtration system, the most important aspects to consider include:

  • HEPA: A HEPA, or high efficiency particulate air filter, is a type of pleated filter that is effective at capturing dust, pollen, and mold spores. It can remove particles as small as 0.3 microns.1 Sometimes, a HEPA filter is made from fiberglass, but is more commonly made of polypropylene, a type of plastic. Products designed to capture even smaller particles may use activated carbon to capture, for example, gases that pass through the primary filter.
  • MERV: The MERV rating scale, originally developed to gauge HVAC filters, is now used to rate the effectiveness of air filters. It most often pertains to whole house purifiers or those that serve large spaces. Filters and air purifiers are rated, on a scale from 1 to 20, based on a series of tests conducted in a controlled environment and repeated several times. However, the MERV system only rates filters based on solid particle removal, not common household gases like carbon monoxide or ammonia.
  • Materials: Fiberglass is effective at trapping large contaminants, but affordability is its biggest advantage. However, more filter media is needed, which impedes airflow slightly. Made from charcoal, activated carbon is highly porous and one of the most effective cleaning materials (although it’s more costly). Plastic-based air filters are durable and reliable. Many are washable, which adds value to their efficiency with no pressure drop or effect on air flow.
  • UV Light: Ultraviolet light destroys bacteria, viruses, and other organic matter. It is especially effective against mold spores. Commonly used in home and commercial air purifiers, UV light is often combined with a HEPA filter for optimal air cleaning.
  • Purpose: The concerns you need to most address determine the best materials and technologies to use. Pet dander, or floating skin cells transported by animal hair, are best removed by a HEPA filter. To remove mold or bacteria from the air, a HEPA filter combined with UV light can be more effective. A HEPA filter with activated carbon is better for people with asthma. It is highly effective at removing allergens from the air, and removes smoke reliably as well. This kind of filter is also efficient at odor removal, as the carbon effectively removes microscopic odor-causing materials without masking the smell.
Air Filter Ratings Explained Infographic

Factors to Consider

Aside from the performance characteristics of specific types of air filters, there are other considerations. Here are additional factors to think about when choosing an air cleaning device for your home, school, office, or other building:

    • Installation: If you’re installing an in-duct air cleaning system, certain requirements must be met. For example, an access point is needed to inspect the device, which is necessary whenever the product is used, maintained, or repaired.
    • Purchasing Costs: The initial price isn’t the only cost you’ll incur. Operating an air filtration system may reflect on your electric bill, while cleaning/replacing filters and other types of maintenance may involve ongoing costs.
    • Odors: Air cleaners designed for odor removal have their limitations. Gas vapors that still pass through can add unwanted odors. When carcinogenic pollutants such as those from tobacco smoke pass through, they still contribute undesirable smells and health risks.
    • Soiling of Walls and Other Surfaces: A problem with ion generators, soiling occurs when the electric charge no longer suspends airborne particles, which may then be deposited onto walls and other room surfaces.
    • Noise: If a portable air cleaner has a fan, it may emit noticeable noise that can be distracting. However, fanless portable units are generally less effective.

Order an Air Filtration System from Nexgen

At Nexgen, we offer several solutions to your indoor air problems, including the AM11, a MERV 11 media air cleaner for air handlers and furnaces. Our product line also includes the duct mounted Air Scrubber, a UV light ionic air scrubber, and the AE14 four-stage filtration system for airborne particles. A lifetime warranty for unit replacement is available, as is a parts and labor warranty when you join our X Protection Plan. To learn more about our air filtration products and their benefits, Our ENERGY STAR rated heating and cooling systems, incentives, and other services we offer in Southern California, call 833-729-9735 today!

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