How does Tesla’s Bioweapon Defense Mode work?

March 21st, 2020 by

From Romance Mode and Sentry Mode to Mars Mode, Teslas have no shortage of extra useful/silly features. One that falls on the “useful” end of that 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 nearly guaranteed to stop all incoming larger particles like dust, smoke, and fumes.

HEPA Filter

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.

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

“When selected, outside air is filtered through the medical-grade HEPA filter in addition to secondary air filtration systems,” says the Tesla owner’s manual. “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 the 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 even 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 inside 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.

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

Tesla Bioweapon Defense Mode

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

They 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. Their data is plotted in the chart below.

In just two minutes, the air inside the car was safely within the EPA’s “Good” rating, the highest on their Air Quality Index, and this was an exaggerated test with pollution well beyond the bounds anything anyone is likely to experience in real life.

Biohazard Line Graph

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

So how do I get it?

The HEPA air filter was originally sold as part of the Premium Upgrades Package in Model X and new front fascia (April 2016 or newer) Model S. 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 it’s missing, 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.