Passengers on Southwest Airlines flights will soon be required to keep their portable chargers in plain sight while using them due to concerns about the growing number of lithium-ion battery fires in a new policy that other airlines may adopt.

This year, there have been at least 22 incidents involving lithium batteries in air travel, according to data from the Federal Aviation Administration.

Southwest Airlines is implementing a new safety policy, effective May 28, requiring passengers to keep portable phone chargers and power banks visible during flights when you're charging a device. The airline will prohibit the use of these devices while they're stored in carry-on bags or overhead bins,