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News Navigator: What kind of ventilation measures can be taken to avoid virus transmission?

An owner of a sports gym in Nagano Prefecture is seen talking to a customer while maintaining a distance and opening a window to ventilate the room on May 7, 2020. (Mainichi/Masahito Minagawa)

The Mainichi Shimbun answers some common questions readers may have concerning ventilation as a preventative measure against the novel coronavirus.

Question: We're spending more time at home as we are refraining from going outdoors as a countermeasure against coronavirus infections. I heard that it's important to ventilate the room frequently in order to prevent infections within the family home.

Answer: That's right. It is said that the general route of infection for the new coronavirus is droplet transmission or transmission via contact with infected people, and that airborne transmission is not a threat. However, ventilating a place thoroughly can help to decrease infection risks.

Q: How can we ventilate a room thoroughly?

A: It's good to open numerous windows and doors so that air coming from outside can circulate through the room, according to the Architectural Institute of Japan and other sources. For those living in a housing complex or other places with just one window per room, it can be effective to open the front door in addition to the balcony window, after taking security measures like leaving the door chain locked.

Q: Lately, there have been houses with "24-hour ventilation systems," right?

A: All houses that were built from July 2003 onward are required to be equipped with this system under the Building Standards Act. It functions so that external air is drawn in and internal air of the room is expelled outside by continuously running a ventilation fan. However, the ventilation system will not prove to be sufficiently effective if the air inlet and exhaust port are blocked by furniture and other objects.

Q: Can a room be ventilated with air conditioning?

A: Regular air conditioners do not have a ventilating function. Please make sure to open windows regularly or avoid turning off the ventilation system, even when the air conditioner is on.

Q: There are places, such as high-rise office buildings, where windows cannot be opened, what should one do under those circumstances?

A: The Building Standards Act specifies the amount of ventilation necessary per person in a room, so each room is usually designed so that they will be thoroughly ventilated. However, a room will become poorly ventilated if a crowd of people exceeding the anticipated number gathers inside. Please be careful to avoid infringing on the 'three Cs' of confined spaces, crowded places and close contact with others.

(Japanese original by Tomoki Okuyama, Science & Environment News Department)

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