最後, 既然要念書, 去搞清楚CADR在測什麼有這麼困難嗎?
https://en.wikipedia.org/wiki/Clean_Air_Delivery_Rate
AHAM recommends following their '2/3' rule. Air filters should be chosen for rooms so that the value of its smoke CADR is equal to or greater than 2/3 the room area in units of square feet (valid for rooms up to 8-foot (2.4 m) in height).[4] This recommendation is based on the assumption that the room will have air exchanged with other rooms at a rate of less than 1 room volume per hour, and that the customer desires at least 80% of the smoke particles removed from the air. For an 8-foot (2.4 m) high room, this means the room volume should be less than or equal to 12 times the CADR value. Much larger rooms can be effectively filtered if there is no air coming from the outside, and if there is no significant continuing source of particulates in the room.[5]

MERV 14 filters are capable of reducing smoke particles by approximately 80% when operating at the filter's design velocity, so a CADR smoke rating on a simple filtering unit that uses a MERV 14 filter will be approximately 0.80 times the fan flow rate in CFM. If the filtering unit does not mix the test room's air very well, it may receive a lower CADR measurement because it does not operate as efficiently as it should. If a filtering unit uses a MERV 12 filter that removes roughly 40% of the smoke particles, then it may still obtain a smoke CADR of 80 by filtering 200 cubic feet per minute instead of 100 CFM. Conversely, a 99.97% HEPA filter (MERV 17) that removes over 99.9% of the smoke particles needs to filter 80 cubic feet per minute to get a CADR of 80. This shows the CFM airflow of a unit is always equal to or greater than the CADR rating.

If half the room's volume of air is exchanged with other rooms every hour, then HEPA filters are not more effective than dust spot 85% efficiency filters (roughly, MERV 13 or 3M's MPR 1900). The unit's fan speed will be the dominant factor if air from outside the room is coming in too quickly
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如果看到這邊, 你還覺得選空氣清淨機, 看濾網等級比CADR有意義, 那就慢走不送了...