What does the Air Exchange Rate mean?

The air exchange rate is telling you how quickly an air purifier can clean the air within the desired space. For example, if your IDEAL air purifier states it’s ideal for a room size of 800 ft² with an Air Exchange Rate of 15 minutes. This means it only takes 15 minutes to clean the air in an 800 ft² room. If the machine runs for 1 hour, it cleans the air in an 800 ft² room 4 times.