Delta Airlines has added more than 400 people to its “no-fly” list during the pandemic for refusing to comply with the airline’s mask policy, according to a company memo obtained by CNN.

“As of this week, we’ve added 460 people to our no-fly list for refusing to comply with our mask requirement,” Delta’s CEO, Ed Bastian, reportedly wrote in the message to employees.

This is an increase of nearly 200 people in the last few months. In July, Delta said they had banned around 240 passengers since the pandemic began.

Major airlines require masks or facial coverings on all flights and many ask for them to be worn at the gate and during checkin at the airport.

In June, airlines agreed to ban customers from future flights for refusing to wear masks, however CNN reports the airlines are not sharing information about the passengers they have banned.