EVALUATION ON INDOOR ENVIRONMENT AND ALTERNATIVE VENTILATION METHODS IN A SCHOOL CLASSROOM IN A COLD REGION UNDER COVID-19 PANDEMIC

COVID-19 caused a global pandemic. The possibility of aerosol transmission has been pointed out as a possible route of infection, and there are reports that conventional infection control measures are insufficient to counteract aerosol transmission. Therefore, this report presents the results of an actual survey at a high school, including measurement of CO2 concentration and a questionnaire survey, and the results of an experiment to evaluate the attenuation of particle concentration by an air cleaner based on this survey.

Dispersion characteristics of oral microbial communities in a built environment

Advances in next‐generation sequencing (NGS) technologies since 2005 have revolutionized biological science. One particular application of NGS technologies is to elucidate microbiomes in built environments. We are currently conducting a series of studies on the elucidation and control of mass infection mechanisms based on dynamic measurement of environment microbiomes. The objective of this study is to clarify the dispersion characteristics of oral bacteria in the built environment. Bacterial communities from occupants’ hands and oral cavities, doorknobs, desk and keyboard surfaces, and air in laboratories were investigated in seven Japanese universities. The median relative abundances of Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, and Fusobacteria were 41%, 31%, 12%, 7%, and 3%, respectively. Moreover, the main genera detected were Streptococcus (27.6%), Haemophilus (7.0%), Staphylococcus (5.6%), Neisseria (5.6%), Corynebacterium (4.7%), Rothia (3.2%), Prevotella (3.0%), Fusobacterium (2.6%), Veillonella (1.7%), Leptotrichia (1.7%), Enhydrobacter (1.7%), Lactobacillus (1.3%), Acinetobacter (1.3%), and Actinomyces (1.1%). The oral bacteria Actinomyces, Corynebacterium, Fusobacterium, Haemophilus, Leptotrichia, Neisseria, Prevotella, Rothia, and Streptococcus were observed in indoor air and on surfaces as well as in oral cavities. Furthermore, Prevotella melaninogenica and Rothia mucilaginosa were observed in all samples, including those from hands and oral cavities, doorknobs, desk and PC keyboard surfaces, and air in laboratories, in all seven universities.

Measures against COVID-19 concerning Summer Indoor Environment in Japan

Information on air-conditioning and ventilation has been continuously disseminated in response to the Japanese Government's announcement of the need for appropriate ventilation measures against the new coronavirus disease (COVID-19), and the issuing of an emergency presidential discourse by the presidents of Engineering Societies. In this paper, we add to the information the latest knowledge on the behavior of SARS-CoV-2 in air, describe its diffusion characteristics in the built environment, and summarize the effects of temperature and humidity on the virus. Then we recommend varying approaches of air-conditioning control for facility type.