Comments on: Are Car Air Purifiers Necessary and Effective for Clean, Fresh Air?

By: d0660

d0660 — Fri, 21 Apr 2023 16:27:43 +0000

Hello, I just randomly stumbled into this old article while doing research on this subject and noticed some flaws I’d like to point out! Not that I expect anyone to answer at this point, but just to clarify things for people like me stumbling into this after all this time!

The argument seems to be “old cars have the same quality air filtration systems as Tesla HVAC’s ‘biodefence mode'” if I understood this correctly. This argument is then justified incorrectly by comparing Tesla to an old car recirculating air already inside the car through a non-HEPA filter over and over again. It should be obvious the air will get cleaner and cleaner like this (probably linearly at about the same pace that the air is being filtered). The reality of the matter is: Tesla has a state of the art HEPA filtration system that doesn’t recirculate air, but takes in new air and then purifies it. The car is also over-pressurized to avoid leaks from outside from getting in without being filtered. The same methods are used in pharmaceutical cleanrooms during medicine manufacturing!

The problem with recirculating air is that while it will also have low levels of outside pollutants like HEPA filtered air, it will start to build up CO2 levels and moisture and the air quality will become bad (not from outside pollutants though).

You can really see the difference in quality of these systems when compared fairly in Tesla’s video comparing their “biodefence mode” (=HEPA+other methods) with BMW’s stock filtration system:

https://www.youtube.com/watch?v=Dx9wrIfqhjM

By: sofien chaieb

sofien chaieb — Thu, 20 Jun 2019 22:45:06 +0000

Can you do the same test in the car Tesla model S who had a medical quality HEPA Filter , please ?

By: Ayush

Ayush — Fri, 23 Nov 2018 05:58:40 +0000

Cabin air filter seems to clean particulates effectively, and as you said, it will not work this good against gases (like NO2, VOCs). Did you perform some tests with gases too? Since some cars might only have an activated carbon filter (like my fiesta), then using a car air purifier would make sense in places like Delhi.

By: Jeff

Jeff — Mon, 11 Dec 2017 05:42:27 +0000

It depends on the filter efficiency rating of the vehicle manufacturer. Having used the Dylos and other improved particles with algorithms that convert to mass concentration, I found many vehicles in India with less than desirable ac cabin filter results ( most were nowhere as good as the Mazda or the Uber in your tests). Not surprisingly the foreign car manufacturers’ results were as good as the Mazda. Some European vehicles have HEPA filter too.

By: Thomas Talhelm

Thomas Talhelm — Mon, 21 Aug 2017 08:51:57 +0000

In reply to David D. Good question! We didn't do that. My guess is it'd be less effective (but still quite effective). For long trips, we might want to use the "bring in outdoor air" mode because CO2 would probably go pretty high in the car.

By: David D

David D — Wed, 28 Jun 2017 14:43:27 +0000

In reply to Jase Davidson. Have you repeated the tests with the AC on but not in recirculation mode?

By: Jase Davidson

Jase Davidson — Sun, 30 Apr 2017 15:11:10 +0000

I think car air purifiers are an excellent concept. Thanks for sharing this article!