Delta has added 460 people to its no-fly list since April for refusing wear masks

© Delta Air Lines Delta adds hundreds to its no-fly list for not wearing masks onboard. Delta Air Lines

• Delta has added a total of 460 people to its no-fly list since April for refusing to wear masks onboard. 
• Delta announced the mask-wearing requirement in April.
• Delta is one of two major US airlines that will block middle seats on planes for the rest of 2020
• Visit Business Insider's homepage for more stories.

Delta has banned a total of 460 people to its no-fly list for refusing to wear masks. 

Delta CEO Ed Bastian said in an email to employees that the company requires customers and employees to wear masks to reduce the transmission of the new coronavirus. Company spokesperson Morgan Durrant said Delta announced the mask-wearing requirement in April.

Bastian said in September the company banned 350 passengers that month, 240 in late-August, and 100 in July 22 for refusing to follow mask protocols. 

Video: Flight Attendants Association president makes case for requiring passengers to wear masks (FOX News)

Read more: An airline pilot reveals the meanings of 24 code words passengers don't understand

Mask enforcement is one of several Delta COVID-19 safety policies. Other protocols include blocking off seats in terminals and airplanes for social distancing, using electrostatic sprayers before flights, and handing customers sanitizing wipes.

Delta is one of two major US airlines that will block middle seats on planes for the rest of 2020. Alaskan Airlines announced Thursday it extended its policy to block middle seats through January 6, 2021. 

Epidemiologists have told told Business Insider's Tom Pallini sitting too close together on airplanes increases the risk of contracting COVID-19 from a nearby passenger. 

As coronavirus cases in the US continue to climb, many companies have struggled to get customers to comply with mask protocols. Employees from several major US brands reported harassment and violence directed at them when they asked shoppers to wear a mask. Retailers like Foot Locker and Dollar Tree stopped enforcing mandatory mask wearing to protect workers.