Health authorities strongly recommended regular indoor ventilation amid signs of a COVID-19 resurgence ahead of the winter season. 

With a guide by the government on ventilation forthcoming next month, health minister Cho Kyoo-hong on Friday emphasized that the risk of infection drops by 38 percent following ten minutes of natural ventilation.

The minister urged high-risk facilities, such as indoor sports centers and coffee shops, to ventilate at least three times a day, for a minimum of ten minutes each time.

The Central Disaster and Safety Countermeasures Headquarters said on Friday that epidemiological investigators from the central and municipal governments were trained in August and earlier this month on ventilation efficiency assessment.

The trained investigators are expected to gauge ventilation efficiency when cases of group respiratory infections are reported.