Tell me about personal air purifiers (no, I'm not in California)
November 19, 2018 9:07 AM   Subscribe

There's been much discussion of personal air purifiers on a cancer support board I participate in. I'd really love some insight and links from MeFites. The most recent related discussion I found on AskMe was in 2015, and it seems like things may have changed since then - apologies if I've missed something.

Like many cancer patients, I'm immunocompromised, so I try to make an extra effort to avoid getting sick. Someone on the cancer board recently posted a question about whether personal air purifiers are helpful when traveling. My Google-fu wasn't super helpful. Most of what I found seemed to be by companies that make them, though it looks like the FDA doesn't support statements that they're helpful. And those statements seem to be related to allergies anyway, not cancer patients trying not to get sick.
Then someone posted that a well-known oncologist who treats our kind of cancer has started traveling with one. And there were a lot of anecdotes along the lines of "I've been using one for two years and I only got sick once" or "speaker-at-a-conference said he started using one five years ago and never gets sick now."
In case it's not clear what I'm talking about, this one was specifically linked to.
I'm planning to travel for the holidays, and I'm trying to decide if I should get one. So what's the deal? Are there real studies? Can they work? Are there theoretical reasons why they should or shouldn't work? Do you have personal experience with one or recommendations about what to look for if I decide to go ahead? I tend to use things in the "won't hurt, might help" category, but this is a lot of money if it's snake oil.
posted by FencingGal to Health & Fitness (8 answers total) 1 user marked this as a favorite
Response by poster: One more thing, please only answer if you can provide real reasons rather than just saying "snake oil."
posted by FencingGal at 9:24 AM on November 19, 2018

Best answer: I don't see how this would even be supposed to work, if I'm honest. The airflow through the claimed zone of effect is vastly more than this could cope with. Any stray breeze which reaches you directly, rather than helpfully choosing to direct itself through the filter first, will be unfiltered. They claim that "the A302 uses state of the art electrostatic purification technology to emit a constant stream of healthy negative ions; This ionic purification forces airborne pollutants out of your personal space creating a 3 foot radius of clean air in all directions", but that's not how electrostatic air purifiers work (they attract dust, they don't repel it).

Edit: Sorry, hit post by accident. Will continue below.
posted by howfar at 9:37 AM on November 19, 2018 [2 favorites]

Best answer: I am in California, and they've been warning against negative-ion or ozone-generating air purifiers because they can create fine particles that further damage lungs. This Time article seems to explain it: You Asked: Should I Use an Air Purifier? So that would be my concern in using one.
posted by lazuli at 9:37 AM on November 19, 2018 [2 favorites]

Best answer: There's also the fundamental point that, if they had an actual medical technology here, they'd have done the research to prove it. There would be studies to support their claims, and they'd be pointing to them, not putting disclaimers up about no medical benefit.

It's not going to hurt you, but neither is tying an onion to your belt, which has as much evidence to support it and costs nearly $70 less.
posted by howfar at 9:41 AM on November 19, 2018

Best answer: Whether it's helpful or not might depend more on what your personal routines are like than anything inherent to the air purifier? Using one at conferences or in hotel settings might help reduce the swirling mass of pathogens that happens when lots of people are traveling and congregating in one room, or might help filter out lingering pathogens in a hotel room, but if you're moving about, or in an airplane seat surrounded by the plane's recirculated air, I'm not sure if a filter could be as effective.

The product you're linking to appears to be an air ioniser rather than an air filter. There is a difference, and research about the effectiveness about ionisers is mixed. Often air purifiers combine HEPA filtration with an ioniser; it's not clear to me that such a small device, working only with an ioniser, would be able to effectively create the 'three-foot bubble' promised in the promotional copy. At best, this probably just replicates the functionality of the overhead air nozzle in a plane seat; there's likely less flow even than that.

Simple practices that you probably already use, like changing out of clothes right away after travel and not touching shared surfaces, would be much more effective.
posted by halation at 9:43 AM on November 19, 2018 [1 favorite]

Best answer: A few of the negative reviews on the Amazon page say that airlines would not allow the purifiers to be used on board, so if you're looking for something to use on a plane, that's another consideration.
posted by lazuli at 10:07 AM on November 19, 2018

Best answer: Certain types of ionic purifiers *can* remove aerosolized micro-organisms (like from coughs and sneezes) from the air. However I see two drawbacks from this device: (1) The battery life looks to be very short and my understanding is that as battery charge decreases, the effectiveness will also decrease, and (2) many of these devices generate small amounts of ozone. That is not a big deal in large, well-ventilated areas but a personal ionic device will not work well in a large, well-ventilated area as the device will be constantly combating fresh air. In a confined space such as an airplane with still air, this device may actually work pretty well, but the generated ozone can build up and cause a problem for people with asthma or other respiratory issues.
posted by muddgirl at 10:40 AM on November 19, 2018 [1 favorite]

This link is from 2011, but it's from a legit source (University of Michigan Health System’s Michigan Sinus Center) and it describes how to build a much cheaper air filter that's just as good as the expensive ones. (Short version: Tape a HEPA filter to a box fan.) If you want to go all-in on the DIY route, and get even better filtering, you can do this.

There appear to be plenty of recent studies on air filtration and infection, but I'm not qualified to summarize them.
posted by clawsoon at 4:31 PM on November 19, 2018 [1 favorite]

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