Tesla’s Bioweapon Defense Mode is helping electric car owners in the California wildfires. The air filtering system in the Model S and X have enabled users to breathe cleanly as particles fill the surrounding atmosphere.

The mode is proving invaluable during this particularly bad spate of fires, which this year have spread across 621,743 acres as of November 4, nearly double that of the 316,654 acres from the same period last year. Tesla owners using the defense mode report good results, with one Twitter user called “amit519” using the mode to combat the “terrible” air quality in Northern California and user “Manic_Marge” using the mode “all day so I can breathe fresh air as the #CaliforniaFires ravage this beautiful state.” CEO Elon Musk reached out via Twitter on Saturday asking for advice on how the company could help with “transporting people” using the hospital-grade high-efficiency particulate air filters.

See more: Tesla Bringing Bioweapon Defense Mode to the Model S

Tesla debuted the filter in September 2015 on the Model X, but it received a somewhat curious response. Musk said the filter would enable Tesla to become a leader in “apocalyptic defense scenarios,” a situation many owners have probably never experienced. Musk claimed the feature would filter viruses 800 times better than normal, and while that may be the case bioweapons expert Randall Larsen laughed when Gizmodo asked whether it would protect against a bioweapon — in part because it’s almost impossible to know that such a weapon has been released.

The feature has proven its worth over time, though, thanks to its ability to provide a clean atmosphere inside the car. The company shared data that showed the feature could bring pollution in a Model X down from 1,000 micrograms per cubic meter to undetectable levels, while also reducing the PM2.5 levels in the outside air by 40 percent. User Olof Tenghoff praised the feature as it helped reduce his daughter’s asthma attacks.

While it’s available on the Model S and X, the feature has yet to become available on the Model 3, something fans want to see changed.

Whether the feature makes its way onto future cars like the Model Y remains to be seen.

Photos via Tesla