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Common Air Purifier Terms

An overview of some common terms you may come across regarding air purifiers, and air purification.


CADR is an acronym for Clean Air Delivery Rate. It is a measure of how much clean air an air purifier can deliver. CADR ratings are important because they tell you how effective an air purifier will be at removing pollutants from the air.

It is expressed in a number of formats, depending on your country. The most common way to express it is in cubic metres per hour (m3/h). It is also sometimes expressed as cubic feet per minute (cfm).

CADR takes into account:

  • Size of the particles removed from the air
  • Percentage of particles removed from the air
  • Volume of air passing through unit

Essentially the higher the CADR, the more air it can clean over the hour.


HEPA is an acronym for High Efficiency Particulate Air. HEPA filtration is a type of air filtration that removes very small particles from the air.

The filters in an H13 HEPA system are able to capture 99.97% of all particles down to 0.3 microns in size. This makes them a very effective tool for controlling air quality, including allergies and asthma symptoms. H13 True HEPA is the level used in the Verdair Air Purifiers.

Due to its power to clean air and reduce the potential level of allergens in the air, HEPA Filters are often used in hospitals, schools, and other public places where people are susceptible to respiratory problems. HEPA filters are also used in workplaces and homes to reduce the amount of dust and allergens in the air.


IAQ is an acronym for Indoor Air Quality. It refers to the air quality within a room or structure, particularly in relation to the health of those in the room.


A micron is a unit of length equal to one-millionth of a metre. It is often represented using the symbol ┬Ám.

For reference, Verdair HEPA filters filter 99.97% of the particles in the air down to 0.3 microns.


TVOC is an acronym for Total Volatile Organic Compounds.

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