# Which way should my air purifier face?

**URL:** <https://boards.straightdope.com/t/which-way-should-my-air-purifier-face/817803>\
**Category:** Factual Questions\
**Created:** [July 12, 2018, 6:49pm UTC](https://boards.straightdope.com/t/which-way-should-my-air-purifier-face/817803 "2018-07-12T18:49:01Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![pohjonen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pohjonen/32/423_2.png) [@pohjonen](https://boards.straightdope.com/u/pohjonen)\
**Post date:** [July 12, 2018, 6:49pm UTC](https://boards.straightdope.com/t/which-way-should-my-air-purifier-face/817803/1 "2018-07-12T18:49:01Z")

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Unfortunately, my kitten Butters is no longer hypoallergenic. I can deal with most of the symptoms except for the ones that affect my lungs. ☹

I purchased an air purifier and bought some of the super dooper allergen reducer filters.

Should the intake be facing the room, or the output?

IOW should the side facing the room be sucking or blowing?

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**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\
**Post date:** [July 12, 2018, 7:45pm UTC](https://boards.straightdope.com/t/which-way-should-my-air-purifier-face/817803/2 "2018-07-12T19:45:45Z")

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Dirty air will approach the intake side of the purifier from pretty much all directions.

Clean air will leave the exhaust side of the purifier in whichever direction it’s pointed.

Such is the nature of fans.

For efficiency’s sake it won’t matter which way the purifier faces, but if you want to breathe the cleanest air possible, point the exhaust side toward wherever you are in the room. This matters more if you’ve just turned it on and are trying to clean dirty air; it matters less if the purifier is running 24/7 and the air leaving the purifier is only incrementally cleaner than the air it’s pulling in.

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**Author:** ![pohjonen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pohjonen/32/423_2.png) [@pohjonen](https://boards.straightdope.com/u/pohjonen)\
**Post date:** [July 12, 2018, 9:54pm UTC](https://boards.straightdope.com/t/which-way-should-my-air-purifier-face/817803/3 "2018-07-12T21:54:28Z")

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Thank you. I run it 24-7 and have tried both directions. Some days I seem less asthmatic than others, but I could not pin down what made the difference.