What is CADR Rating in Air Purifiers?

/ Air Filtration & Purification / January 29

Air Purifier Against Tiled Wall—What is the CADR Rating in Air Purifiers

If you’re shopping around for a portable air purifier to place in your home or office, you may have seen a label displaying a “Clean Air Delivery Rate,” or CADR. While at first glance, it may seem like just a bundle of numbers, the CADR rating of an air purifier is actually an important tool to utilize when deciding on which air purifier is best for you. So if you’re in the market for improving your indoor air quality, knowing what a CADR rating is and how to utilize it will help make the buying process easier.

Below is a guide about Clean Air Delivery Rate, how it’s measured and tested and how you can utilize it better.

What is a CADR?

The CADR (or Clean Air Delivery Rate) is a numerical rating that informs of an air purifier’s effectiveness in cleaning the air in a space. Simply put, the CADR is based on how many particulate contaminants the unit can remove from the air and how much air the unit can clean. The higher the CADR rating an air purifier has, the more particles it can remove, and the larger the area it can clean in.

What Does a CADR Rating Look Like?

CADR Energy Label Exampe--What is a CADR Rating in Air Purifiers

Image from Gadget Review

Once certified, an air purifier’s CADR rating looks like a series of three numbers that are divided by back-slashes. Each number in the series corresponds with the type of contaminant the unit can clean.

How is an Air Purifier Tested for CADR?

The CADR that’s present on an air purifier was independently-tested by the Association of Home Appliance Manufacturers, or AHAM. To calculate and then certify an air purifier with a CADR rating, AHAM conducts two tests to cross-compare. In one test, the unit undergoes specific testing that measures how effective it is at removing various particle sizes from the air at the highest fan speed. This result is compared to another test conducted in the same controlled environment, but without utilizing the air purifier unit.

By testing the air purifier this way, AHAM can determine how much and how well an air purifier cleans the air in a space by comparing it to the controlled environment. Once AHAM has determined how well an air purifier performs in a space, they then designate the unit with a three-number rating for each type of contaminant.

What Types of Contaminants Does a CADR Cover?

When establishing a CADR, multiple pollutant sizes are tested and measured to then inform the consumer of the air purifier’s effectiveness to improve indoor air quality. In the simplest of terms, the CADR certification process measures small, medium and large pollutants; the pollutants measured based on their size include cigarette smoke (small), dust (medium) and pollen (large). Since small particulate pollutants and contaminants have the capability to enter deep into a person’s respiratory system—like the lungs—an air purifier with a high CADR rating that corresponds to small particulates is more effective at purifying the room of that contaminant.

CADR, CFMs and Room Space 

More often than not, CADR is usually accompanied by another acronym: CFM. CFM, or cubic feet per minute, is a measurement commonly used in the HVAC space, and it describes the amount of air that passes through an air purifier. The higher the CFM, the more air the unit draws in to cycle through and purify, so having a high CFM is important with an air purifier. A general rule-of-thumb when it comes to CFMs is to know that 100 CFM is needed for every 200 sq. ft.CADR per Square Feet Infographic--What is the CADR Rating in an Air Purifier

CADR and its relationship to CFMs is important for determining how well that air purifier will work in a room. If you’re unsure if the CADR of your air purifier is right for your space, AHAM recommends that the CADR needs to at least reach or be equal to ⅔ of the room’s area to work efficiently.

As an example, if your air purifier has a smoke CADR rating of at least 80, it can properly clean a room of that size contaminant in a room with a square footage of 120. So, knowing the CADR helps inform how large of a space it can properly work in. If you have an air purifier with a CADR that isn’t correct for your room or space, it won’t effectively clean the air in that area.

For more information on how to shop for an air purifier, explore our comprehensive buying guide on the types of air purifiers.

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