In the development of room deodorant, it is important to identify the components of room odor. Thus, in this study, we collected the odors in the living rooms of five households ((1)-(5)) of different dwelling styles, family structures, and lifestyles, and examined their main components. We measured 18 odorous substances considered to exist in common households.
As a result of our analysis, the following odor components were detected in all households: Trimethylamine, Methyl sulfide, Acetic acid, n-Valeric acid, Caproic acid, Acetaldehyde^*, Hexanal, Heptanal, n-Octanal, Nonanal, and 2-Nonenal. On performing odor index conversion of the concentration of the detected substances and calculating the contribution ratio, aldehydes amounted to 64.9 - 85.5 % and acetic acid amounted to 5.8 - 18.9 % in all households, regardless of the living environment.
The results suggest that, in the development of room deodorants, approximately 80 - 90 % of the room odor can be neutralized by deodorizing aldehydes and acetic acid.
^* We did not collect aldehydes from Household (1).

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A survey was conducted with two free standing houses to study the diurnal variation of airborne fungi in rooms of common houses. One of the two houses was located in Kodaira City in Tokyo and the other in Ageo City in Saitama Prefecture. Examination was carried out twice, each lasting two days, in July 2012. An air sampler, Dichloran 18% glycerol agar, was used to collect airborne fungi in rooms every two hours to a total of 13 times and collected fungi were cultured. Concentrations (cfu/m³) of airborne fungi were calculated from numbers of colonies, from which fungi were isolated and identified.
Results of this study showed that concentrations of airborne fungi tended to increase in both houses in the morning from 4 a.m. to 8 a.m. This tendency was remarkable in fungi of genus Aspergillus, which is believed to pose problems as an allergen. Among isolated fungi of genus Aspergillus, many species belonged to Aspergillus section Restricti. Results of this survey indicate that allergenic fungi inhaled by residents in their sleep are a possible cause of asthmatic seizures occurring from midnight to early morning.

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Recently, air pollution by Particulate Matter 2.5 (PM_2.5) has been inviting great social concerns due to its potential adverse effects on human health. Since PM_2.5 is a complex media defined by particle size, corresponding particulate matter exists even in indoor environment. This paper overviewed toxicological and epidemiological studies on the aspect of human health effects of PM_2.5 and summarized the present understandings. Sequence of events related to setting exposure limits on PM_2.5 was also mentioned for the cases of USA, WHO and Japan.

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