Question: Do you really need a special filter to filter out ultrafine particulates in the air?

BostonFern is asking a question about air-quality
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by BostonFern | February 11, 2020 07:52 | #22751

I know there are manufacturers that make air purifier that can filter out particulaters smaller than 0.3 um, which is what HEPA filter can filter. But, according to this webpage, a normal HEPA filter should be able to capture particulates of any size, including the ones smaller than 0.3 um.

Their reasoning is that ultrafine particulates move in a zigzag way and can get easily stuck somewhere, and the particulates that are most difficult to filter out is 0.3 um, which HEPA can filter.

What do you think?


Hey @BostonFern thanks for posting. I don't have an answer for this question, but check out this page, it has some info on ultrafines on it. I think the graphs are helpful :

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My expertise is chemistry. But in working in a glp/gmp lab environmenment, I was trained in some of it.

The major concern with HEPA filters was eliminating bacterial contamination. Initially, bacteria were thought to be no larger than 0.5 um. A few years later, some bacteria were found that were 0.3 um in size, which led to the reduction in filter size.

But to try and take that further is really pushing it. There would need to be A lot of work proving these filters could capture nanoparticles before it would be acceptable. When you are talking about the FDA (all the validations and other steps required), realize what is involved both in time and money.

Good luck.

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