The South Korean government put forth guidelines on when and how to wear protective masks and use air conditioning to prevent further spread of COVID-19 during the summer season.

The measures come as more than two million students ranging from kindergarten to high school returned to schools on Wednesday.

According to the central disaster and safety countermeasures headquarters, students should wear masks indoors, but they can take them off outdoors while keeping a two-meter distance from each other.

Those experiencing headaches or difficulty breathing can temporarily take off the masks while standing away from others.

Authorities also advised multi-purpose facilities to ventilate every two hours when operating air conditioning to prevent potential spread of the virus through droplet transmission. If ventilation is not an option, all visitors should wear masks.