How does Tesla’s Bioweapon Defense Mode work?

From Romance Mode and Sentry Mode to Mars Mode, Teslas have no shortage of useful and/or silly extra features. One that falls on the “useful” end of the spectrum is Bioweapon Defense Mode.

Despite its dramatic name, Bioweapon Defense Mode will protect occupants from a variety of more mundane dangers as well. It’s designed to filter out all sorts of hazardous particles in the air, including exhaust fumes, smoke, allergens, airborne pathogens, and anything else potentially dangerous out there.

This lung-protection capability is thanks to a HEPA air filter and some clever HVAC work.

HEPA, short for High Efficiency Particulate Air is a standard for air filters developed by the United States Department of Energy. In order to meet the standard, a filter must be able to stop 99.97% of particles 0.3 micrometers in diameter.

For an idea of just how small that is, human hair can have a diameter of anywhere between 17 and 181 micrometers. A piece of paper might be anywhere between 70 and 180 micrometers thick.

And if the HEPA Air filter stops 99.97% of all particles 0.3 micrometers thick, it’s pretty much guaranteed to stop all of the larger particles breezing by a vehicle like dust, smoke, and fumes.

Tesla’s HEPA Filter as shown on their online shop. | Source: Tesla

The difference between a standard air filter and the HEPA filter is stark. Your lungs will notice a difference when driving through areas with poor air quality, like stop-and-go highway traffic, California wildfires, and smelly animal farms.

You need to activate Bioweapon Defense Mode to use the HEPA filter, which works quickly to expel all pollutants from the car and keep them out.

According to the Tesla owner’s manual:

When selected, outside air is filtered through the medical-grade HEPA filter in addition to secondary air filtration systems. Both the HEPA air filter and secondary filtration system also contain activated carbon to remove a broad spectrum of odors and gasses. When you engage Bioweapon Defense Mode, the fan operates at the highest speed. In addition, positive pressure inside the cabin minimizes the amount of outside air that can leak into the vehicle.

In a practical sense, it gets a little louder inside the car while Bioweapon Defense Mode is running. Keeping the fan at max speed ensures quick circulation to remove pollutants and helps to maintain the positive-pressure environment—an element taken from hospitals to help prevent the spread of pollutants and pathogens into rooms with vulnerable patients.

Basically, the car is pressurized relative to the outside world like an airplane is at altitude. The difference is that the Tesla is very lightly pressurized, not enough for the passengers to notice—just enough to make it so the environment inside the car wants to push air out instead of sucking air in.

Air is only allowed inside through the filtration system, ensuring passengers are protected from pollutants, pathogens, and anything else in the air outside the vehicle.

The system is really effective, too. Tesla itself ran a test to prove its capability and show off the system before release.

The test setup to prove Bioweapon Defense Mode. | Source: Tesla

It put a Model X in an inflatable bubble filled with pollution well beyond the Environmental Protection Agency’s measurement of “Hazardous” and turned on Bioweapon Defense Mode. Data from the test is plotted in the chart below.

Tracking pollution inside and outside Model X during test. | Source: Tesla

In just two minutes, the air inside the car went from beyond hazardous to safely within the EPA’s “Good” rating—and this was an exaggerated test with pollution well beyond the bounds of anything anyone is likely to experience in real life.

So how do I get it?

The HEPA air filter was originally sold as part of Tesla’s Premium Upgrades Package in the Model X and the new front fascia Model S produced in April 2016 and after. The package was made standard for both vehicles in July 2018.

To confirm that your Tesla has bioweapon defense mode just look at your HVAC control screen. If this biohazard symbol is present, you’ve got it. If the HEPA filter is missing from the vehicle you own, you can actually purchase a retrofit from Tesla’s website. Model X and Model S with new front fascia can receive the upgrade for $500, which includes shipping and installation at a Tesla service center.

And if you’re in the market for a Model S or Model X, take a look at our current inventory and don’t hesitate to reach out to one of our EV specialists with any questions via phone, email, or chat. We make it easy to find your EV, buy it online, and get it delivered.