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JACA (Japan Air Cleaning Association)

The Abstracts of the paper carried by the Journal of JACA

vol.58-2(2020/7/31)

Ventilation and air conditioning design of facilities for the elderly

In elderly facilities, it is difficult to make sufficient capital investment to maintain a good indoor environment, and there are some problems in operation.
This paper summarizes a survey on the indoor environment of elderly facilities and classifies the design methods and cautions for air conditioning and ventilation.
In addition, the report describes the key points to be considered in the design and operation of ventilation plans to prevent infection, which will become increasingly important in the future.

Indoor environment and health effects

Since 1970, indoor air quality standards has been determined by Building Hygiene Act in Japan. Due to this act, Sick Building Syndrome has not occurred for a long time in Japan, but similar syndrome has come up to appear in private houses in 1990s. Methods to measure concentrations of indoor air pollutants are described in detail. Importance of ventilation is emphasized to keep high indoor air quality.

Behavior of airborne microorganisms and health effects

The new coronavirus infection is an emerging infection that has been first detected on November 22, 2019 in Wuhan, People’s Republic of China. The virus has been named SARS-CoV-2 by International Committee on Taxonomy of Viruses. Infection with this virus has spread worldwide.
In Japan, on April 7, 2020, the government has positioned the seven prefectures of Tokyo, Saitama, Chiba, Kanagawa, Osaka, Hyogo and Fukuoka Prefecture as special caution prefectures. Furthermore, on April 16, the state of emergency has been announced to all prefectures nationwide. After that, the national emergency declaration has been lifted on May 25, but the new coronavirus infection are running on. It is feared that the second and third waves of this new virus epidemic will come in the near future.
This paper introduces the establishment of infectious diseases, infection routes, viruses, droplets and droplet nuclei, environmental standards for indoor microorganisms, and infection prevention. Currently, the preventive measures we can do are not to be intimate, to be careful of sealing, to avoid crowding, to be a habit of washing hands, and to be a habit of wearing a mask.
There is still little scientific knowledge about the new coronavirus. In the future, the development of vaccines and therapeutic agents against this virus will be important issues.

Ventilation effectiveness of displacement ventilation and impinging jet ventilation

The effectiveness of a ventilation system strongly depends on its air distribution strategy. This article first gives a brief explanation of a general way to evaluate ventilaton effectiveness, which can be classified into two concepts, i.e., indices based on the age of air, and that based on contaminant concentration. Then, a full-scale laboratory experiment in a climate chamber is introduced, where displacement ventilation (DV) and impinging jet ventilation (IJV) system is installed. The ventilation effectiveness of these two efficient systems is finally to be shown and compared with each other.