“This is a real button,” said Musk Tuesday while unveiling the new vehicle, according to The Verge. The car’s air filter “gives you hospital level air quality,” Musk said.

Musk said that the button can be used “if there’s ever an apocalyptic scenario of some kind.” By pressing the button, the model’s air filter kicks into its maximum level of filtration. “We’re trying to be a leader in apocalyptic defense scenarios,” Musk said.

Per The Verge:

All you apparently have to do is push the button and the Model X’s air filter — which is about 10 times larger than a normal car’s air filter— should be able to keep you safe. The company claims it’s 300 times better at filtering bacteria, 500 times better at filtering allergens, 700 times better at filtering smog, and 800 times better at filtering viruses

Still, driving into a biohazard zone is probably not recommended.

For more on Tesla’s new Model X, here’s Fortune’s report on the new car.