In this study, we used the clean air delivery rate (Q_eq)[m³/h] as an index for the removal rate of gaseous pollutants by atmosphere-type air fresheners in a practical application. Using this index, we formulated a new evaluation method and made a preliminary assessment of the performance of six liquid air fresheners (five "natural" type fresheners and one general-purpose freshener) and of purified water for removing volatile organic compounds (VOCs) and formaldehyde.
The results showed that formaldehyde was efficiently removed by two fresheners; liquid air freshener (1) with the main ingredients being extracts from 35 types of plants and liquid air freshener (2) with the main ingredient being phytoncide. The Q_eq of liquid air freshener (1), and (2) were 0.41 and 0.45 m³/h, respectively, with liquid air freshener (2) showing a slightly higher Q_eq than liquid air freshener (1).
Total volatile organic compound (TVOC) removal was observed for three of the six air fresheners. The VOC Q_eq (TVOC converted values) of all three fell within the range of 0.40-1.11 m³/h. Liquid air freshener (4), which was composed of water and added minerals, had the highest removal rate with a VOC Q_eq slightly higher than that of purified water (0.16 m³/h).
Overall, the liquid air fresheners removed between 6 and 11 out of 17 VOCs. Liquid air freshener (5) with main ingredients being chamaecyparis obtuse and eucalyptus essential oils showed the removal of the greatest number of VOCs.

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Phthalic acid esters (PAE) are typical substances of semi-volatile organic compounds (SVOC) and are widely used as plasticizers. This study performed fundamental examination on gas-particulate phase percentage in indoor air of three PAEs, namely DBP, DEP and DEHP by employing a glass fiber filter and two C₁₈ porous polyflon filters in a room that wallpaper was used. The mean concentrations of PAE were the order of 1 μg/m³. DEP of small molecular weight was almost gas-phase and more than 60% of DEHP of large molecular weight was particle-phase. On the other hand the greater part of DBP of middle molecular weight was gas-phase, however, when the room temperature was low, the percentage of particulate phase tended to increase.
Authors have made a passive sampler for SVOC, which is large in a sampling rate due to a windbreaker and diffusion-membrane-less sampling face. Parallel measurement with both active and passive sampling was applied to obtain the sampling rates of DEP, DBP and DEHP. In addition, the measured sampling rate was compared with theoretical sampling rate, which was calculated with a sampler dimension and diffusion coefficients. The sampling rates of gas-phase DEP and DBP were almost consistent with the theoretical sampling rates. However, further investigations should be required on the practical application of this passive sampler, because the influence of airflow was significantly found on the sampling rates.

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Recently, a household refrigerator is becoming large enough to store a large quantity of foods and beverages, and airtight for energy-saving and hence reduction of carbon dioxide (CO₂) emissions. However, this type of change in structure may cause air contaminations by gaseous chemicals such as ethylene, odor gases and carbonyl compounds which has been found in air of refrigerators. Such chemicals potentially influence on food freshness and human health. In order to investigate the behavior or fate of such chemicals in the refrigerator, the air leakage and/or change rates should be one of the important parameters. However, no data has been previously reported on the air leakage and air change rate of household refrigerators. Then, the authors practically measured the air leakage and air change rates of a household refrigerator (225 L) using two tracer gas methods; CO₂ decay method and Hexafluorobenzene(HxFB)-Passive Sampler(PS) method, which has been commonly used for the measurement of air change rate of houses. The both methods were firstly tested to measure air change rate of the refrigerator with pulling air at constant rates of 0.2, 0.3 and 0.4 /h. Relative error of the measured values by both methods ranged from 2 to 30% to the set values. The air leakage rate of the closed refrigerator was then obtained by CO₂ decay and HxFB-PS methods, and no significant difference was found between the respective measured values. These results showed the both methods were applicable for the household refrigerator, even though the temperature was low. Then, the air change rate of the refrigerator with openings and closings was measured by the HxFB-PS method. In this case, the CO₂ decay method seemed not suitable due to rapid and intermittent decrease in gas concentration. According to JIS C 9801 method, the doors of cold room and freezer were opened 35 and 8 time per day respectively, during 3 days. The air change rate resulted in 0.36 /h, which were close to double the air leakage rate of the refrigerator.

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We investigated air concentrations of tobacco smoke-related chemicals in 26 office buildings in Tokyo in 2005 and 2006. Measurements were conducted in (a) smoking rooms, (b) non-smoking areas adjoining smoking rooms and (c) non-smoking rooms such as office rooms. Chemical substances analyzed were nicotine, formaldehyde, acetaldehyde, acetone, propionaldehyde, toluene, benzene, carbon monoxide (CO) and particulate matter (PM). The maximum values of nicotine were (a) 267 μg/m³, (b) 16.7 μg/m³ and (c) 1.2 μg/m³, and the detection rates were (a) 100%, (b) 38% and (c) 4%, respectively. Reasons why nicotine was detected in the non-smoking areas are attributed to leakage of tobacco smoke from smoking rooms and a transportation of nicotine adhering to smokers. In smoking rooms, the concentrations of PM and CO were positively correlated to that of nicotine, and hence PM and CO concentrations may be useful indicators for the air quality. In contrast, because of their poor correlation in non-smoking areas adjoining the smoking rooms, it may be difficult to estimate a nicotine level by PM and CO concentrations.

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