The Environmental Protection Agency (EPA) states that indoor air pollution is among our top five environmental health risks. And while ventilating with clean outdoor air is a solution, it’s not always practical. Weather conditions and outdoor air pollution often make it difficult or impossible.
The EPA goes on to say that air cleaning devices may be the answer. But if you’ve done any research online, you’ve discovered many different kinds of air purifiers. You’ll see terms such as “HEPA,” “activated oxygen,” “air filtration,” and “ionic comfort.” Then there are portable or whole house, contractor installed HVAC systems along with cleaners, filters, and fans.
If you’re confused about air purification products, you’re not alone. So what’s best for you and your family?
A good place to start is to evaluate what indoor air pollutants may be in your house. The EPA divides them into two categories: particulate matter and gaseous pollutants.
Particulate matter may come from organisms such as dust mites, molds, bacteria, and viruses. It can be dust, smoke, animal dander, or particles from combustion in the home such as stoves and fireplaces.
Gaseous pollutants originate with combustion and from materials found in and around the house. Stoves, vehicle exhaust, tobacco smoke, and wood smoke produce gaseous pollution.
Household products also release gasses, called volatile organic compounds (VOCs) into the home. This “off-gassing” can originate in building materials such as particle board and home furnishings. Off-gassing also occurs when you use paint, varnishes, or common household cleaning products.
Every home is different and the weather, pollen count, and outdoor air is unique to each region of the country. Plus, the people living in your home may have special medical conditions such as asthma. If they’re young children or seniors, they will also be more vulnerable to indoor air pollution.
Some air purifier systems and portables are designed to remove certain types of pollutants from your air. Other air purifiers work to destroy the pollutants.
There are really two types of air purifiers: whole house air purification systems and portable air purifiers. Whole house air purification systems take care of the entire home from kitchen and bathrooms to bedrooms and living areas. A portable air purifier works best in single rooms. Portable air purifiers are extra protection in an infant’s or child’s bedroom or the bedroom of an elderly parent or a family member with asthma or allergy sensitivity.
Here’s more on how different air purifiers work to control indoor air pollution…
To rid the air of polluting particles, purifiers use either mechanical air filters or electronic air cleaners.
• Mechanical filters capture particles on the materials in the filter. HEPA, or High Efficiency Particulate Air filters are mechanical air filters.
• Electronic air cleaners use electrostatic attraction to trap particles. These cleaners draw air through an ionization section that electrically charges the particles. The charged particles accumulate on a series of oppositely charged plates called a collector. Ion generators, also called ionizers, don’t use a collector but disperse the charged ions into the air. There they attach to other airborne particles so they’ll adhere to walls and furniture, or attach to one another and thus settle faster.
A sorbent such as activated carbon is used in gas-phase air filters to adsorb gasses and odors. This removes them from the air. Adsorption is the adhesion of atoms, ions, or molecules from a gas to a surface, in this case the filter.
The thing to look out for in gas phase filtration systems is that they usually work on only one or a limited number of gaseous pollutants. They will not work on gasses that they were not designed for. And none remove all the gaseous pollutants in a typical home’s air. For example, carbon monoxide is one gas that is dangerous but not easily captured by today’s air purifiers.
Air cleaners that use ultraviolet light (UV) to destroy indoor air pollutants are called ultraviolet germicidal irradiation (UVGI) cleaners and photocatalytic oxidation (PCO) cleaners. Some manufacturers also sell air cleaners that produce ozone to destroy pollutants. But, as you will see, that is not a recommended option, as ozone is a known lung irritant.
• Ultraviolet Germicidal Irradiation (UVGI) kills biological pollutants using short-wavelength ultraviolet light. These UV lamps destroy viruses, bacteria, allergens, and molds in the air or growing within HVAC systems. UVGI systems are typically used in hospitals to kill airborne pathogens, preventing the spread of disease.
• Photocatalytic Oxidation (PCO) incorporate photon and UV energy to activate a catalyst that destroys gasses (VOCs). In simpler terms, light energy quick-starts the process of turning pollution causing molecules into more harmless substances.
• Ozone Generators use UV light or an electrical discharge to produce ozone. Supposedly, the ozone destroys pollutants, but this is disputed by scientists and the EPA. They are often sold as providing “activated oxygen,” “super oxygen,” “trivalent oxygen,” “allotropic oxygen,” or “saturated oxygen” when they are talking about ozone.
The EPA and other government agencies have determined that ozone generators are not safe and they do not effectively eliminate indoor air pollutants. When you shop for air purification in your home, the best advice is to stay away from any system using ozone generation. According to the EPA, “At concentrations that do not exceed public health standards, ozone has little effect in removing most indoor air contaminants. Thus, ozone generators are not always safe and effective in controlling indoor air pollutants.”
There are two kinds of air cleaning devices you can buy. You can get a whole house air purification system installed in the ductwork of your HVAC system. Or you can buy a portable air cleaner for one room only or if you do not have a forced air heating/cooling system.
The quality of filters installed in your ductwork are measured in terms of their efficiency in removing airborne particles from the air that passes through them. The measurement is called the minimum efficiency reporting value, or MERV. The ratings range from a low of 1 to a high of 20.
• Filters with a MERV of 1-4 are generally not meant for controlling indoor air quality, but to protect the HVAC equipment.
• A MERV rating of 5 to 13 is reasonably efficient at removing particles from the air, according to the EPA.
• A MERV of 7-13 can be almost as effective as HEPA filters. HEPA stands for high-efficiency particulate air. To qualify for a HEPA rating the filter must meet certain government standards. The nice thing about MERV filters of 7-13 is that they are usually less expensive than HEPA filters. Plus, they’re quieter since they have less air-flow resistance.
• Higher efficiency filters of over 13 are generally not installed in residential HVAC systems. They are more commercial grade for hospitals and require special installation. If you are thinking of purchasing a higher efficiency filter, be sure to consult with your heating/cooling professional. Some residential HVAC systems may not be able to accommodate them because of insufficient fan or motor capacity.
Portable air purifiers are measured by their clean air delivery rate, or CADR. The Association of Home Appliance Manufacturers developed this measure of a portable’s delivery of contaminant-free air in cubic feet per minute. So, let’s say an air cleaner has a CADR of 150 for dust particles. That means it reduces dust particles in a room to similar levels if you were to add 150 cubic feet of clean air per minute. The higher the CADR, the better the filtration.