Here’s What Tesla’s HEPA Filter and “Bioweapon Defense Mode” Actually Do

Tesla made a big deal about the fact that its cars have an enormous HEPA filter and an impressive-sounding Bioweapon Defense Mode. But what do these things actually do?

High-Efficiency Particulate Air (HEPA) filters work by forcing air through a very fine mesh filter. “This type of air filter can theoretically remove at least 99.97 per cent of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm),” according to the U.S. Environmental Protection Agency. For comparison, an N95 mask only removes, “at least 95 per cent of airborne particles,” according to the U.S. Centers for Disease Control and Prevention (CDC).

Introduced in the Model X, Tesla’s “Bioweapon Defense Mode,” — which, yes, is actually called that — is a button drivers can push. Once activated, the HEPA filter rapidly cleans the air inside a vehicle, as Tesla demonstrated in this test.


“In less than two minutes, the HEPA filtration system had scrubbed the air in Model X, bringing pollution levels from an extremely dangerous 1,000 µg/m3 to levels so low as to be undetectable (below the noise floor) by our instruments,” the company claimed.

Thankfully, nobody has actually had to put Bioweapon Defense Mode to the test in the real world (to our knowledge, at least). However, during last year’s devastating California wild fires, Tesla drivers took to social media to report that these unique features did help them breathe easier in their cars even as black smoke filled the air. In increasingly uncertain times, Tesla is always two steps ahead.