Tests
Why Formaldehyde Detectors Are Not as Effective at Formaldehyde(HCHO) Testing as You Think
Lots of companies will sell you formaldehyde sensors, 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 impossible to interpret. Given that unfortunate fact, here’s what you can do …
HEPA Filter Fan Placement: Should Air Purifiers Have the HEPA Filter on the Front or Back?
Should air purifiers have the HEPA 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 …
Half of Chinese N95 Masks Fail Quality Checks
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 …
Sanitizing Masks With Alcohol Degrades Performance
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 …
The Ultimate Guide to Homemade Face Masks for Coronavirus
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 …
ALL Purifiers Perform Worse When Air Pollution is Bad: (And How to Fix It)
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 …
DIY Cannon: Better, Faster, Stronger
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: …
DIY Purifier Tests
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 …
