A peer-reviewed study from the University of Texas finds that ionizers increase air pollution, creating formaldehyde, ozone, and particulate. This data contrasts sharply with claims from air purifier companies that market ionizers as magical machines. One company in China claims that their machine’s negative ions “remove PM2.5 particulate pollution and …
How can we make a homemade DIY air purifier? Air purifiers can be extremely expensive. But they don’t need to be. After researching how different air filters work, I concluded that a HEPA filter is all that’s needed to make an effective air purifier. Given that most air purifiers sell …
Tests of masks marketed as N95 from 21 manufacturers show that half of Chinese N95 masks fail quality tests–with some masks filtering no better than a cotton cloth. These tests come at a time that many countries around the world are scrambling for masks and other PPE. Factories Spring Up …
With mask shortages during the coronavirus outbreak, some doctors are sanitizing masks with alcohol so they can re-use them. But this raises questions about whether alcohol actually works and whether it degrades the masks. Does Alcohol Kill Viruses? The research on alcohol is clear. Alcohol kills viruses. Technically, viruses aren’t …
One month ago, we published one of the first rundowns of data on the best materials for making homemade masks. Fast forward and the CDC is now recommending face masks for everybody, spurring a worldwide movement to make homemade masks. The first summary (viewed over 4 million times!) was a …
Should air purifiers have the filter on the front or the back–is it better to push or pull air? The Smart Air lab in Beijing ran tests of the same fan with the HEPA filter on either side, and the results contradict most people’s intuition. When I made my first …
Lots of companies will sell you formaldehyde detectors, but a simple test you can do at home will reveal they are fakes. Formaldehyde detectors routinely react to lots of common gases that are not formaldehyde, making the numbers basically impossible to interpret. Given that unfortunate fact, here’s what you can …
Most air purifier companies hide the fact that outdoor air pollution drastically affects air purifier performance – even when used indoors. When outdoor air pollution is bad, purifiers achieve a smaller percentage reduction. It becomes harder to reach safe levels indoors. Here’s what you can do to ensure you are …
Ever since I started my DIY filter experiments, I’ve been wondering whether I could create a super DIY by using a stronger fan. In the past three months, my collaborator Anna has helped me test a half dozen different fans. She now has a home full of fans: …
How do I know if a DIY purifier works? I think you can break this down into two questions： Is the air coming out of the DIY purifier clean? The test results are as clear as can be. The DIY purifier shoots out very clean air. But is that enough to actually …
