The air quality can be significantly improved and felt after the air purifier is on for about 30 minutes.
Please keep in mind that the effectiveness depends on the room size, level of contamination, and the fan speed setting of the device.

For some sources of pollutants, even a few minutes of air cleaning will be noticeable, but “aged” pollutants like smoke particles that have migrated into the wall, carpet, or furniture, will be hard to totally eliminate.

When the air purifier is turned off, the trapped pollutants will continue to deliver contamination to the room until the filter is cleaned or unless the air purifier is left on.