Nitrogen dioxide (NO₂) in indoor air is generated from heating appliances, gas ranges, and cigarette smoke. These substances are proven causative substances for respiratory diseases; and as preventive measures in Japan, atmospheric environmental standard and school environmental hygiene standard have been set.
In Japan, Saltzman method or chemiluminescence method is adopted as a standard measurement method for NO₂ in the air. Among these methods, the Saltzman method is inconvenient to handle with a wet method using absorbing solution for trapping NO₂. On the other hand, the chemilumines-cence method has a large and expensive apparatus. In this study, in order to improve these point, the following measurement method was developed. This method is an NO₂ measurement method by HPLC using a 1-hydrazinophthalazine (1-HP) reagent, a mixed scavenger of triethanolamine (TEA) and sodium hydroxide as a scavenger. In this method, an active sampler filled with a scavenger in a glass tube was prepared and basic investigation such as collection efficiency, extraction method, repeatability, comparison between theoretical value and analytical value etc. was carried out. As a result, the collection efficiency for NO₂ was 99% and above for one of the collection tubes, the repeatability was 4.1% or less in terms of the relative standard deviation, and the lower limit of determination (0.3 L/min x 30 min) was less than 0.01 ppm. Moreover, a significant correlation was found between the proposed method and Saltzman method, which is a standard test method for NO₂. From the above viewpoint, the practicality of this method became clear.

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Railway operators are performing various evaluations and taking various countermeasures concerning odors at restrooms in stations, as one of public restrooms, with many opinions by railway customers. Up to now, we have been explored odor sources with detection tubes easy to handle by using ammonia which is a representative odor component of restrooms as an indicator of the odor. But, in many cases, ammonia was not detected even at restrooms that fed unpleasant odor because the detectable concentration of the detection tubes was higher than detection threshold concentration (0.1ppm). Therefore, it sometimes did not lead to the detection of odor sources. So, a method for detecting ammonia with lower concentration has been needed in order to make it possible to search for ammonia odor sources on site.
To cope with such a situation, we made a prototype of a portable system for detecting ammonia using a sensor device for gaseous ammonia with higher detection sensitivity developed in the past. And we carried out demonstration tests with this prototype at three restrooms in stations with different odor strength. As a result, we confirmed that using this system, we could detect ammonia having lower concentration and that we could presume the location of the source of the ammonia odor in about 5 minutes.

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Naphthalene (NP), primarily used as a moth-repellent in residences, is indicated to be possibly carcinogenic to humans. Therefore, it is concerned about health effects of the residents by long-term exposure to NP. Generally, airborne NP is analyzed after active sampling with a suction pump. In the present study, a simultaneous analytical method was described for determination of airborne NP with p-dichlorobenzene (DCB), one of the moth-repellents widely being used in residences, by gas chromatography/mass spectrometry (GC/MS) after passive sampling, which was a convenient method that required no suction pump.
NP and DCB in indoor air were collected for 24 hours by using a commercial passive sampler packed with 200 mg of activated charcoal. The target compounds collected were extracted from the activated charcoal with 1 ml of toluene after addition of their surrogates as internal standards, and were quantified by GC/MS.
The calibration curves for determination of NP and DCB were linear at the concentrations of up to ca. 400 and 600 μg/m³, respectively, as airborne concentrations (quantification limits: NP, 0.09 μg/m³; DCB, 0.04 μg/m³). The coefficients of variation of the quantitative values for the compounds on replicate assays of the whole preparation were less than 7%, which indicate good reproducibility. These compounds in used sampler were stable for up to two months at 4°C in the dark.
The present analytical method was simple and precise for determination of airborne NP, and could simultaneously quantify DCB.

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From this issue, the title was “Recent topics related to microorganisms in the indoor environment,” and sequential explanations were provided by six members of the microbe subcommittee. The problem of microbes in the indoor environment is a serious public problem every year. Many problems must be overcome, such as “allergies from indoor environment pollution caused by mold,” “infectious diseases and allergies in workplaces and public facilities,” and “allergies and infectious diseases in temporary housing provided during natural disasters such as earthquakes, typhoons, volcanic eruptions, which have become frequent in recent years.” These explanations, describe the housing and workplace environment, with regard to the following: Contamination and actual status of microbes, infection route, health effects and countermeasures Introduction: Describes the changes in housing morphology and diseases. Three routes of infection by microbes in the indoor environment are particularly important: 1) droplet infection (droplet infection), 2) airborne infection (air borne infection), and 3) fomite infection (food/contact) infection (vehicle-borne infection). Airborne infection should be regarded as a problem in the modern airtight indoor environments of houses and public facilities that must be considered for the increase and countermeasures of allergic diseases. Indeed, nasal and paranasal sinus diseases in kindergarten to high school students are highly prevalent, particularly among elementary and junior high school students. In addition, the number of elderly people 65 years of age or older with asthma has increased in recent years. Continuous inhalation of airborne fungi is a concern.

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