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.

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,

Southwest says it will limit battery charging to devices that are easily visible, in case chargers catch fire.