Distribution of Airborne Bacteria in Railway Stations in Tokyo, Japan

Abstract

Distribution of Airborne Bacteria in Railway Stations in Tokyo, Japan: Tamami KAWASAKI, et al. Biotechnology Laboratory, Railway Technical Research Institute— Objectives We performed the current study to (1) understand the distribution of culturable airborne bacteria over a one‐year monitoring period, (2) confirm places in stations where airborne bacteria are highly detected, (3) understand the factors that affect concentrations of airborne bacteria and (4) compare the distributions of airborne bacteria and fungi in railway stations in Japan. Methods Measurements of airborne bacteria were taken at stations A and B located in Tokyo. Station A had under‐ and above‐ground concourses and platforms, whereas station B had spaces only above‐ground. Airborne bacteria at each measurement position were collected with an air sampler on plate count agar media. After cultivation of the sampled media, the number of bacteria colonies was counted on each media. Results (1) Airborne bacteria were highly detected in the above‐ground concourse in station A. Almost all the indoor‐to‐outdoor (I/O) ratios of concentrations of airborne bacteria in the above‐ground concourse in station A were higher than one throughout the year and were especially high in summer. (2) The factor that affects the concentrations of airborne bacteria seems to be the number of railway customers, not humidity. (3) The characteristics of the distributions of airborne bacteria and fungi were different, even though they were sampled in the same stations on the same days. Conclusions In the case of controlling indoor air quality of stations in the future, the locations in railway stations that would require control of indoor air quality differ between airborne bacteria or fungi, respectively.

The microbiological condition of public air in the city during autumn and winter

“…People also bring their overclothes, which may contribute to the increased amount and diversity of microorganisms in this part of the cinema. A similar observation was provided by Kawasaki et al (2013). They detected a high number of airborne bacteria in a railway station and it was especially high in summer.…”

“…They detected a high number of airborne bacteria in a railway station and it was especially high in summer. They concluded that the number of railway customers, not humidity, was the main factor affecting the concentrations of bacteria [29]. The next exanimed building of public interest was a pharmacy.…”

Indoor-Air Microbiome in an Urban Subway Network: Diversity and Dynamics

“…Whether this observation can be applied and generalized to bacteria in aerosols and to those of different indoor environments is unknown. Nonetheless, one should use caution in such generalizations and comparisons, as environmental effects such as temperature and humidity on microbial community assemblages are likely to be influenced by sample locations, method of sampling, and the microbial members and communities in question (17,59,60). When outlier samples based on their high taxonomic diversity were removed, the effects of temperature and humidity on MTR ␣-diversity no longer were significant.…”

“…Unfortunately, the microbiological contents of the aerosol in this unique built environment are relatively unknown. The majority of current microbiological assessments of subway networks had been limited to conventional culture methods (8)(9)(10)(11)(12)(13)(14)(15)(16)(17) or limited culture-independent methods (18,19), which are likely to underestimate the true spectrum of microorganisms present. Culture-based studies are also inherently restrictive in the comparison of microbial communities between samples, as the organisms cultivated for analysis are dependent on the selective growth conditions chosen.…”

“…As a result, these studies are limited to insensitive comparisons of microbial concentrations between samples, with crude analysis on the composition of microbial communities. While these cultivation-based studies demonstrated the roles ridership (10,11,17), time (18)(19)(20), and station location and design (8,12,13,15) play in microbial concentrations and diversity in subway air, it is not known whether this difference is representative of the entire phylogenetic spectrum present given the methodologies employed. According to the only sequencing-based subway microbiome study conducted to date (21), subway air is made up predominantly of a small number of microbial phyla and families, and its community composition resembles that of outdoor air.…”