SAN FRANCISCO, Calif. (KRON) – All BART trains in service are now equipped with newly upgraded filtration systems to fight against the spread of COVID-19.

After a successful pilot, BART leaders say they’ll be ready for more riders this holiday season.

The biggest changes in these BART trains are the type of filters they’re now using. 

All trains are now equipped with stronger filters, recycling the air every 70 seconds from outside.

Bracing for the holiday season, more visitors and the potential to increase the spread of COVID-19, BART has equipped all of its trains with stronger, more dense filters providing more protection against the virus.

“We just upgraded all of our filters from a MERV-8 to a MERV-14 style filter and what that does is basically a MERV-14 style filter allows us to capture much more particulate, the MERV-14 particulate down to as small as 8/10th of a micron. For reference, a human hair is about 70 microns,”

Engineer Charles Franz explains the higher the MERV number, the more effective that filter system is against preventing transmissions. With this new system, he says the air is recycled every 70 seconds from outside.

“Each HVAC has two filters, two HVACS on each car for a total of four filters and what that’s doing is it’s bringing in air from the outside. It’s also bringing in air from the cabin and passing it through a filter, much like a coffee grind in a coffee filter,”

After many months spent on the project, BART hopes to reassure its riders.

“They can rely on a safe ride on BART and they’re breathing fresh air and that we’re taking as many steps as we can to mitigate the coronavirus risk,”

BART says it changes and replaces those filters every two to three months.