Better Decisions Through Data.
Cheap air filters when you can’t afford to make a fashion statement?
Air pollution is serious enough to create elevated cancer, trigger allergies and asthma is of concern in nearly every major city in the world. However, according to NASA, the worst PM2.5 pollution is in Chinese and Indian cities, places where it may be difficult for the average citizen to afford a traditional, consumer-grade air purifier. As most people don’t want to wear a mask all day long and look like a medieval plague doctor, the hunt is on for other cheap technologies, such as dirt cheap air filters and purifiers.
[UPDATE:Â Thomas Talhelm of Smart Air Filters emailed us some comments/corrections on the article. We’ve included these in the comments below.]One Chinese/American startup, based in Beijing and the US [Update: they are mainly in Beijing], may have a solution. Smart Air Filters has come up with inexpensive kits consisting of little more than a fan, some duct tape [Update: it’s a velcro strap], and a HEPA filter. (The low end on these already cheap air filters apparently only has duct tape and maybe the HEPA filter.) The kits are aimed primarily at China and other developing markets. It does look like they’ll ship to the US, and the cost listed on their website is around USD$30-50 depending on the exact kit.
They provide “proof” on their blog page that the kits “work.” They’re even using a Dylos to “prove” that their inexpensive duct-tape solution works and cleans the air. (And some of the counts when he moves back into the room show pretty dirty air in the room, so I’m curious as to where it was filmed.)
A problem with their analysis
There’s a problem with their website and video demo. What they call “PM2.5” is actually intended to be the PM10 channel, and what they call “PM0.5” is intended to measure PM2.5 levels. (Readers with our app can do the conversion into US EPA AQI equivalents and see just how bad their air is!)
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Thomas Talhelm of Smart Air Filters emailed us some comments/corrections on the article.
He writes:
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Just saw your article. Thanks for the shout out! Would you mind if I suggest a few edits?
1. I’d just say based in Beijing. I’m currently at the University of Virginia, but the action’s really in Beijing.
2. Was the use of the word “duct tape” metaphorical? We don’t use duct tape. We have straps custom made for the machines. (“Custom” makes it sound fancier than they are. They’re velcro straps, and the “custom” is that the manufacturer makes them to the specific length and color we request.)
3. The room in the video was in the hallway of my apartment in Beijing. I was not running a filter prior to filming the video, so those counts can be considered “normal” for indoors in Beijing.
4. I think “error” is a strong word for the labeling of the different channels. I think there’s a case to be made for our labeling system. PM means “particulate matter” and “.5” is microns, and the Dylos surely is measuring .5 micron particulate pollution. Now, your suggestion for labels may be better (and I’m seriously considering switching to it!), but I think it’s a bit far to call ours an “error.” Besides, all of the Y-axes in our graphs are clearly labelled as X size and above, so readers have the more exact definition in every graph.
5. Finally, good point on the slow speed and the UL listing. I don’t see the DIY as the end game. We’re working with a manufacturer to get a commercial product with regulatory safety approval. Also, our more powerful cannon model does rival the Blue Air and Philips in speed and overall effectiveness, and it still costs far less (although it’s noisier than I’d like). I’d be happy to share that data with you.
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Hi Thomas,
1. Sorry for mistaking the velcro straps in the picture for the duct tape, we didn’t look closely. Thanks for the correction! (Incidentally, we _have_ tested an air filter using duct tape. Not HEPA but MERV13 in front of a forced air intake that didn’t accept an air filter — think most US code probably requires them to accept air filters. But if yours doesn’t, or doesn’t accept the filter you want, this is one solution. You can’t really use a HEPA for forced air unless it is designed that way, otherwise you risk burning out your fan motor. MERV13 is designed for forced air systems, but, of course, isn’t as good as getting rid of the smaller PM2.5 particles.
2. Sorry, there’s no way you can claim the left Dylos channel is PM0.5. You’ve mislabeled stuff in your article, so you might want to fix it. (You know that truth in advertising kind of thing.)
PM0.5 generally means particles smaller than 0.5 microns, which the Dylos does NOT measure. The left channel measures 0.5-2.5 microns, hence many particles smaller than 2.5 microns. So it would be more accurate to call this PM2.5 (rather than PM0.5 as you call it.)
The right Dylos channel (which you are calling PM2.5) measures 2.5-10 micron sized particles. Therefore, to accurately estimate PM10, you’d need to combine the two channels together to get a 0.5-10 micron reading. But, as a first pass, you could relabel what you call PM2.5 to PM10.
To really get it accurate you’d want to run it through something like our app to get the US EPA AQI equivalents for both PM2.5 and PM10. This would take care of combining the two channels together to get you PM10, and adjust for the weather and humidity. We’d be happy to help you do this.
[…] Talhelm of Smart Air Filters, Inc. (see our article) wrote a comment on our Facebook […]
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[…] of PM2.5 air quality pollution. Things like inexpensive dust particulate sensors for your home, ultra-cheap DIY air purifiers made from duct tape. We’ve run a fashion section with inexpensive masks that are handy to keep stockpiled not […]
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