Korean Air announced Tuesday it will enforce stricter rules for passengers to wear masks on board planes as part of safety efforts to prevent COVID-19.

Starting Sept. 8, the national flag carrier will not allow passengers to board if they refuse to wear a mask, in an effort to stop the spread of the virus, with the exception of toddlers younger than 24 months and those with health conditions.

The move is part of the airline’s Care First program, which consists of prevention and disinfection measures to respond to the pandemic from checking in at the airport to getting on board.

If a passenger continues to refuse to wear a mask after boarding the plane and resorts to violence or verbal abuse, a warning will be issued before police are involved. Unruly passengers can also be refused from booking flights with Korean Air in the future based on their behavior.

Since wearing masks became mandatory in late May, however, the airline added that no passenger has been denied boarding.

By Yim Hyun-su (hyunsu@heraldcorp.com)