When shopping for a new product, the first place people turn is often the internet. Shopping for an air purifier is no different. With a wealth of “top ten air purifiers” articles - for allergies, removing smoke or mold, or, most recently, being effective at capturing the SARS-CoV-2 virus (1) - there is endless information at your fingertips.

However, sorting through this information to find the right air purifier for your business, school, or office is more difficult, especially when it seems as if you need to learn a new language to understand the articles you’re reading. From CADR to micron, we wanted to break down some of the key terms you may come across when shopping for an air purifier.

Activated Carbon: Carbon air filters are typically used to remove smoke, strong odors, or harmful gases. Also known as a charcoal filter, activated carbon filters work by trapping gas molecules on a bed of charcoal. Carbon filters cannot remove fine particles in the air and are often used in conjunction with other filters that capture particles from the air.

CADR: Clean air delivery rate (CADR) is a common measurement in evaluating air purifiers and stems from the assumption that a good air purifier will need to move air quickly. A device’s CADR rating is given in CFM, which stands for cubic feet per minute. However, experts explain that CADR ratings only show the cleaning capacity, not the cleaning capability. A more coarse filter will naturally be able to push air faster than more precise filtration systems. If you want to determine cleaning capability, look at the specific filters and the particle size they filter down to.  

HEPA: High-efficiency particulate air filters (HEPA filters) are pleated mechanical filters. HEPA filtration standards call for the elimination of 99.97% of airborne particles down to 0.3 microns, or 300 nanometers. A HEPA filter is the most common mechanical filter and was commercialized in the 1950s.

ISO Classifications: In some instances, you may see that an air purifier references ISO cleanroom standards. Specific cleanroom classifications and ISO class code descriptions provide protective guidelines and secure environments through controlled air filtration. There are eight different ISO ratings, and classifications are given based on the amount of particulate matter of a specific size per cubic meter within a given enclosure. The lower the ISO class, the more particle-free the environment is.

Micron: A micron is a unit of length equal to one-millionth of a meter. It is often used to measure particle size. Another unit of measure used is a nanometer (nm), and 1 micron = 1000 nanometers. For reference, a strand of hair is about 75 microns across, whereas a mold spore is 3 microns, and the flu virus is only 0.127 microns (or 127 nm).

Off-gassing: What we often think of as a “new product smell” is actually off-gassing from paint, coatings, or gasses that were trapped somewhere in the manufacturing process. Off-gassing occurs when items release volatile organic compounds (VOCs) or other chemicals into the air. This can come from new products in your building or office, cleaning products, or even furniture. Mechanical air purifiers can help remove these dangerous gasses from the air.

ULPA: ULPA stands for ultra-low particulate air (filter) and can remove at least 99.999% of any airborne particles of 100 nanometers in size. This is a more fine air filter classification than a HEPA filter, filtering particles three times smaller.

VOC: VOC, or volatile organic compounds, are emitted as gases into the air from certain solids or liquids. While we often think of outdoor air pollution, studies have found that levels of several organics average 2 to 5 times higher indoors than outdoors (EPA). They are released by many common household products, including cleaners and cosmetic products. 

As you familiarize yourself with these key terms, let us know what other terms we should include on our social media channels! Still not sure where to go from here? Check out our blog on “4 key questions to consider when buying an air purifier.”


(1) The Celios G200 Advanced Air Purifier meets the performance and labeling requirements provided in the U.S. Food and Drug Administration’s March 2020 Enforcement Policy for Sterilizers, Disinfectant Devices, and Air Purifiers During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency, published March, 2020 (the Celios G200 Advanced Air Purifier has not been cleared by the FDA). Specifically, the Celios G200 Advanced Air Purifier has demonstrated up to 99.99999% filtration efficiency of ultrafine airborne particulate matter and is capable of filtering particles down to 10 nanometers in size. The Celios G200 Advanced Air Purifier has also demonstrated up to 99.99999% virus filtration efficiency of ΦX174, a small bacteriophage virus with a maximum diameter of ~32 nanometers.

The G200 Advanced Air Purifier is not intended to prevent or protect from any form of illness or disease (or otherwise). To reduce the risk of fire or electric shock, do not use this fan with any solid-state speed control device. Unplug or disconnect the appliance from the power supply before servicing. The appliance is only to be used with the power supply unit provided and it must only be supplied with voltage corresponding to the marking on the appliance. Do not operate any fan with a damaged cord or plug. Discard fan or return to an authorized service facility for examination and/or repair. Do not run cord under carpeting. Do not cover cord with throw rugs, runners or similar covers. Do not route cord under furniture or appliances. Arrange cord away from traffic areas and where it will not be tripped over. Do not allow children to operate the G200 Advanced Air Purifier or play near the G200 Advanced Air Purifier. Only plug the power cord into a standard electrical outlet. Do not use outdoors. Do not immerse the G200 Advanced Air Purifier in liquid and do not handle the G200 Advanced Air Purifier with wet hands. Do not insert a finger or foreign object into the airflow openings. Do not use the G200 Advanced Air Purifier in toxic or explosive environments or where flammable or combustible gases are present.

October 13, 2022 — Stephanie Giera
Tags: Celios