To explain influences of airborne microorganisms in a university rooms, we studied the seasonal changes of concentration (cfu/m3 and cells/m3), I/O ratio (In/Out ratio), identification of Gram-positive cocci and sources of airborne fungi and bacteria. The concentrations of airborne bacteria and fungi, in the three rooms, that is a conference room, a practice room, and a laboratory, and outdoor of a university, were measured by the impaction method and the filtration method once a month during two and a half years. Viable fungi concentration (cfu/m3) in the rooms exceeded the standard value of Architectural Institute of Japan (AIJES-A0002-2013, Office: 50 cfu/m3≧) from summer to autumn every year, suggesting that the fungi were inflowing from outside air through the air conditioning system. A high value of viable fungi concentration was observed in Jul. 2012, but such high concentration was not recognized after that and no generation sources were recognized in this room. On the other hand, viable bacteria concentrations were almost satisfied AIJES-A0002-2013 (Office: 500 cfu/m3≧) during the same period. But, in the laboratory and the conference room that were frequently used, I/O ratios of viable bacteria often exceeded over 1, suggesting that the source of fresh bacteria was in the room. Moreover, most of I/O ratios of bacteria obtained from total cell concentration (cells/m3) were not greater than 1. Therefore, measurement of airborne bacteria by the impaction method was considered to be suitable for understanding relatively recent influences. Based on Gram staining, composition of bacteria detected in the room was simple compared to outdoor, and there were many Gram-positive cocci, such as Staphylococcus spp including S. epidermidis and S. hominis, and genus Micrococcus by api test, from the frequently used rooms. Accordingly, it was strongly suggested that sources of those bacteria were occupants.
In recent years, individual fragrance spray equipment has become very popular. We can spray of aroma preferred by the operator within a certain range. It is useful if we can use the most effective fragrance for individuals to improve work performance or reduce stress. We made a hypothesis preference of fragrance has large effect on performance and reduction of stress. Therefore, it was set a preference of fragrance as a parameter, and the experiment of applying a workload to subjects was conducted. Three essential oils were used: "grapefruits" was preferred by the all subjects, "anise seeds" was hated by the all subjects and "blue gum" was preferred by half of the subjects. Measurement of salivary amylase and heart rate, and evaluation of current moods was conducted. The number of correct answers was almost not effected by preference of fragrances. Indexes of salivary amylase were not also effected by preference of fragrances. In indexes of parasympathetic activity, "grapefruits" were high score although there was no significant difference. In evaluations of mood, "grapefruits" were higher than "anise seeds" about all evaluation items. Consequently, preference of fragrance effected on moods of subjects, though the preference didn't effect significantly on work performance and stress. In addition, we compared between the measurement values by the "like blue gum" group and the "dislike blue gum" group. Therefore, the "like blue gum" group were higher score of workloads than the "dislike blue gum" group, and they also had more positive results in the indexes of stress, parasympathetic activity and sympathetic activity though there are no significant difference. From these investigation, it was revealed the possibility of the preference effect of fragrances, and it's essential to investigate by using more subjects.
We measured an indoor nitrogen dioxide (NO2) concentration in the winter of Sendai by using a sensor element that employed a diazo coupling reaction in a porous glass. The questionnaire survey and measurement results of 95 houses were gathered, and the obtained results were that the average NO2 concentration was 91.6 ppb indicating high indoor air concentration, and the percentage of the data that exceed environmental standard value of NO2 (60 ppb) was 53.7%. Especially, the higher NO2 concentration than the environmental standard and the large percentage of the data that exceed environmental standard has been measured at both the house with an oil stove for heating (150.9 ppb and 81.8%) and the house with an oil fan heater for heating (139.0 ppb and 80.0%). On the other hand, the lower NO2 concentration (59.5 ppb) than environmental standard has been measured at the houses with 24-hour ventilation system. Considering these results, ventilation was an important factor to reduce an indoor NO2 concentration, and the indoor NO2, which was mainly emitted from the combustion-type heater, was extremely high in the case of insufficient ventilation. In Sendai area, it was found that people did not pay attention to ventilation in the winter, because the outside temperature was very low and the ventilation would sometimes lead a decrease in indoor temperature. Therefore, people tend to live in the indoor condition containing the higher NO2 concentration than that in other area of Japan.
The process of monitoring of volatile organic compounds present in indoor air at a newly constructed building was undertaken in 2015. We detected 2-butanone oxime at a maximum concentration of 3,570 g/m3. The emission source of 2-butanone oxime was silicone sealant used in the construction of the building. The adsorption of 2-butanone oxime with thermal desorption using a Tenax TA sampler was suitably accurate to trap 2-butanone oxime under both low- and high- humidity conditions. It was confirmed that 2-butanone oxime was stable under high humidity (relative humidity: 80%), and the Tenax TA sampler, with a flow rate of 0.1 L/min, was able to stably measure data for 2 h. The emission source of both 2-butanone oxime and 2-butanone was a silicone sealant used in the building. This was determined by placing a glass plate coverd with the silicone sealant in a Tedlar® Bag for 2 weeks, and analyzed by Gas chromatograph/Mass spectrometer (GC/MS). Air in a Tedlar® Bag was sampling every other day throughout the 2-week period. A maximum concentration of 2-butanone oxime was observed after approximately 1 week, and it gradually decreased thereafter. The concentration of 2-butanone in the bag gradually increased throughout the sampling period; however, its production rate was low in comparison to the decline rate of 2-butanone oxime.
April 03, 2017 There had been a system trouble from April 1, 2017, 13:24 to April 2, 2017, 16:07(JST) (April 1, 2017, 04:24 to April 2, 2017, 07:07(UTC)) .The service has been back to normal.We apologize for any inconvenience this may cause you.
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