Understanding Air Purifiers

Understanding AIr Purifiers
(Common Terminology used with Air Quality)
ACH or Air Change per Hour:  The number of times per hour that the volume of air in a specific room or building is purified within that space by mechanical and/or natural ventilation.

Activated Carbon and/or Charcoal:  Activated carbon, also called activated charcoal or activated coal, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for absorption or chemical reactions. Commonly used in air purifiers along with HEPA filters for odor absorption of many airborne pollutants.

AHAM Certification:  AHAM, the Association of Home Appliance Manufacturers, independently tests and rates air cleaning products based on the Clean Air Delivery Rate (CADR) or the amount of particulate that is filtered by the appliance. This helps to identify the efficiency of the products by room size so that you can make sure you are purchasing an air cleaner that will suit your home needs.AHAM administers a voluntary Room Air Cleaner Certification Program for portable household electric room air cleaners.

Air Purifier and/or Air Cleaner An appliance used to remove impurities from the air, perhaps by means of a filter.

Air Sterilizer:  Use of internal heat within the unit to incinerate airborne mold spores, bacteria, fungi, and viruses. Most of the time without the use of a filter.

Animal or Pet Dander:  Dander is material shed from the body of various animals, similar to dandruff or pet pollen. It may contain scales of dried skin and hair, or feathers. It is a frequent cause of allergy in humans.

Asthma:  Asthma is characterized by a predisposition to chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed. Asthma affects 7% of the population of the United States and 300 million people worldwide. During asthma attacks, the smooth muscle cells in the bronchi constrict, the airways become inflamed and swollen, and breathing becomes difficult.

CADR:  Clean Air Delivery Rate (CADR) signifies the amount of clean air delivered by an air purifier.  Three numbers are usually listed for each air purifier (one for tobacco smoke, one for pollen, and one for dust).  The higher the tobacco smoke, pollen and dust numbers, the faster the unit filters the air.  The CADR determines how well an air purifier reduces these pollutants.

Carbon and Zeolite:  Carbon and zeolite are materials used in some air purifiers that remove gases and odors. Both have properties that allow them to absorb gaseous materials and pollutants.  Zeolite is a cheaper version and is not nearly as effective as carbon. Both compounds are usually blended together in a mixture for use in air purifiers. 

CFM or Cubic Feet per Minute:  The amount of air, in cubic feet, that flows through a given space in one minute. 1 CFM equals approximately 2 liters per second (l/s).

Dust Mites:  The house dust mite (sometimes referred to by allergists as HDM), is a cosmopolitan guest in human habitation. Dust mites feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. House dust mites are a common cause of asthma and allergic symptoms worldwide. Some of the gut enzymes (notably proteases) produced by the house mite persist in their fecal matter, and can be strongly allergenic.

Filterless Air Purifier:  Air purifier without a filter to purify the air in a given space. Common technologies used for filterless air purifiers are air sterilizers and ionic air purifiers which use their own given technologies to clean the air.

HEPA:  Stands for High Efficiency Particulate Air. HEPA filters can capture 99.97% of particles as small as 0.3 microns. Can also capture 95-99% of particles below 0.3 microns. HEPA filters were originally designed to capture and remove microscopic particles such as radioactive dust in atomic plants. HEPA filters are a mainstay in areas that require clean air such as hospitals, clean rooms, and high-tech manufacturing plants.

Ionic (Electrostatic Precipitator):   Basically, air is drawn through an electrical field.  As the particles in the air pass through the electrical field, an electronic charge is given to them. The charged particles are then attracted to a series of flat plates with an opposite electrical charge. Effectively removes many particles from the air, such as allergens, fine dust particles, some bacteria and viruses, chemical fumes and other ultra-fine particles.  This process usually causes a small amount of ozone to be created.

MCS or Multiple Chemical Sensitivity:  A chronic disease caused by a person's inability to tolerate a variety of environmental substances. Most often chemical odors within the environment from such sources as household items to car exhaust fumes.

Microban is the global leader in antimicrobial protection that is built into products. From cutting boards to humidifiers, bathtubs to carpeting, socks to caulking, Microban antimicrobial action keeps products cleaner and fresher between cleanings, for the life of the product. Safe and effective, Microban helps you create a cleaner home environment for you and your family.

  A unit of length. One Micron = 39 millionths of an inch. Contaminant size is usually described in microns. Relatively speaking, a grain of salt is about 60 microns and the eye can see particles to about 25 microns. A micron is also known as a micrometer.


Here are some common household particles and their relative size:
0.3 - 1 micron = Tobacco Smoke, Bacteria, Metallic Fumes
1 - 5 microns = Bacteria and Small Dust Particles
5 - 10 microns = Mold, Pollen, Medium Dust Particles
10 microns = Large Dust Particles
25 microns = Debris and Dust Particles (visible to the naked eye)
150 microns = Human Hair

Off Gassing or Out Gassing:  Term used particularly when in reference to indoor air quality. It is the slow release of a gas that was trapped, frozen, or absorbed in some material. That "new car smell" would be an example of off gassing.

Ozone:  An unstable derivative of oxygen, O3, that is formed naturally in the ozone layer from atmospheric oxygen by electric discharge or exposure to ultraviolet radiation. It is a highly reactive oxidizing agent used to deodorize air, purify water, and treat industrial waste.

PCO - Photo catalytic Oxidation Grid: Transforms odors, germs, and VOCs into fresh breathable air without producing ozone.  This advanced technology destroys volatile organic compounds (VOC's), bacteria, mold and fungus by incorporating photon and ultraviolet (UV) energy activating a catalyst creating PCO.

Pre-filter:  A filter used in many air purifiers that is designed to capture particles 1 micron in size and larger. Some air purifiers use activated carbon as their pre-filter to remove odors and gases. A pre-filter will extend the life of a HEPA filter.

Square Feet (Sqft):  Common measurement for determining area of space in a home or workplace in regards to air purification efficiency for air purifiers and/or air cleaners.

ULPA filter ULPA, also known as Ultra-HEPA, filters are designed to trap 99.999% of all airborne particles 0.3 microns or smaller from the air that pass through the filter. These include tobacco smoke, household dust, and pollen.

Ultraviolet (UV) Sterilization:  Ultraviolet light is used in some air purifiers to destroy microorganisms such as bacteria, mold and viruses. It is usually not the main filtering element, but an additional layer of purification and protection within certain types of air purifiers. Most commonly used in conjunction with HEPA and charcoal filter air purifiers.

UVC:  Ultraviolet with the wavelength of C.   UVC Germicidal Wavelength is a type of UV light from 280nm-200nm (254 nanometers) and is a high intensity germicidal lamp that neutralizes and reduces airborne mold, bacteria, and viruses.

VOCs (Volatile Organic Compounds):  Volatile organic compounds (VOCs) are organic chemical compounds that have high enough vapor pressures under normal conditions to significantly vaporize and enter the atmosphere. Volatile organic compounds are numerous and varied. Although ubiquitous in nature and modern industrial society, they may also be harmful or toxic. VOCs, or subsets of the VOCs, are often regulated.