What Does China's National Standard for Air Purifiers Cover?

CADR has relatively little to do with price, and a larger number is not always better. One purifier with a CADR above 800 placed in the living room will be less effective than two purifiers with CADR ratings above 400 placed separately in the living room and dining room.

II. Noise

Noise also has relatively little to do with price, but it determines whether users can sleep well while breathing clean air. For sleeping, noise below 40 dB is acceptable to the author, although individual tolerance varies.

III. Applicable Area

Do not expect one purifier to clean an entire home unless the home is very small. A rough calculation based on indoor particle concentration is: applicable area = CADR × 0.07-0.12. The multiplier should be lower when the particle concentration is higher. For example, a purifier with a CADR of 400 gives 400 × 0.1 = 40 m², although this calculation is only approximate.

IV. Purification Energy Efficiency

Compared with filter cost, electricity use is only a small expense and need not be weighted too heavily. If the issue is considered only from an environmental perspective, an electricity-free life in a natural forest would be greener than city living and would also eliminate the cost of an air purifier.

V. Emission of Harmful Substances

There is generally little need to worry about a purifier that relies entirely on physical filtration. With an electrostatic purifier, however, pay attention to ozone. The ozone issue in an electrostatic design is relatively easy to address: adding an activated-carbon filter at the outlet substantially reduces concern about ozone, while an additional medium-efficiency filter prevents carbon dust from escaping.

Some commentary incorrectly criticizes Blueair products over ozone. Their design uses only a small electrostatic brush rather than the electrostatic cell found in a fully electrostatic air purifier. The principal drawback of an electrostatic-cell purifier is the need for frequent cleaning, making it less convenient than a purifier based entirely on physical filtration.

VI. Microbial Removal

Only an air purifier equipped with a filter that removes microorganisms needs to state this performance indicator.