As summer approaches in Japan, experts are raising an alarm that the use of air conditioners may lead to heightened risks of contracting the coronavirus and developing COVID-19. 

The novel coronavirus is generally not transmitted through the air, but is passed through droplets from coughs or sneezes, or by touching virus-contaminated objects.

However, speaking with many people in closed places at a short distance can lead to infection risks, even without coughs or sneezes.

According to Masayuki Ishida, a doctor specializing in infectious diseases at Chikamori Hospital in the western Japan city of Kochi, large droplets usually fall to the ground quickly but smaller ones stay in the air for a longer period of time.

The use of air conditioners can lead to tiny droplets with the coronavirus hitching a ride on the wind to travel through the air, raising the risks of infection even for people staying far away from infected individuals.

Ventilation is important to prevent such risks, considering the fact that most air conditioners recirculate air within a space, which means that they don’t draw fresh air in from outdoors.

"It is desirable to have a change of air for five to ten minutes every hour," Ishida said.

"Two windows facing each other should be opened to create a flow of air, but if there is only one window, an air circulator or fan should be placed on the opposite side to create a wind blowing toward the window."

As for air purifiers, only high-performance models are considered effective in eliminating viruses.

"It is unclear whether the use of ordinary air purifiers is fully effective as a countermeasure against the new coronavirus," said an official of the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan.

Air conditioning equipment maker Daikin Industries Ltd. is introducing detailed ventilation methods on its webpage and accepting telephone consultations. 

JIJI Press