Yoshika Sekine

Oxidative decomposition of formaldehyde by metal oxides at room temperature

Formaldehyde (HCHO) is still a major indoor air pollutant in Japanese air-tight houses and is the subject of numerous complaints regarding health disorders. Authors have developed a passive-type air-cleaning material and an air cleaner using manganese oxide (77% MnO2) as an active component and successfully reduced indoor HCHO concentrations in newly built multi-family houses. In this study, the reactivity between manganese oxide and HCHO was discussed. We tested the removal efficiencies of several metal oxides for HCHO in a static reaction vessel and found manganese oxide could react with HCHO and release carbon dioxide even at room temperature. The reactivity and mechanisms were discussed for the proposed chemical reactions. A mass balance study proved that a major product through the heterogeneous reaction between manganese oxide and HCHO was carbon dioxide. Harmful by-products (HCOOH and CO) were not found.

Simultaneous removal of formaldehyde and benzene in indoor air with a combination of sorption- and decomposition-type air filters

Urgent measures for indoor air pollution caused by volatile organic compounds are required in urban areas of China. Considering indoor air concentration levels and hazardous properties, formaldehyde and benzene should be given priority for pollution control in China. The authors proposed the use of air-cleaning devices, including stand-alone room air cleaners and in-duct devices. This study aimed to find the best combination of sorption and decomposition filters for the simultaneous removal of formaldehyde and benzene, employing four types of air filter units: an activated charcoal filter (ACF), an ACF impregnated with a trapping agent for acidic gases (ACID), a MnO2 filter (MDF) for oxidative decomposition of formaldehyde at room temperature and a photocatalyst filter (PHOTO) coupled with a parallel beam ultraviolet (UV) irradiation device. The performance of the combined systems under air flow rates of 35–165 m3 h−1 was evaluated in a test chamber (2 m3) with a constant gas generation system. The experimental results and data analysis using a kinetic approach showed the combined system of ACF, PHOTO and MDF significantly reduced both concentrations of formaldehyde and benzene in air without any unpleasant odours caused by the UV-induced photocatalytic reaction. The system was then evaluated in a full-size laboratory (22 m3). This test proved the practical performance of the system even at full scale, and also suggested that the filters should be arranged in the order of PHOTO/ACF/MDF from upstream to downstream. The proposed system has the potential of being used for improving indoor air quality of houses and buildings in China.

Measurement of concentrations of thioglycolic acid, dithiodiglycolic acid and ammonia in indoor air of a beauty salon.

Measurement of Concentrations of Thioglycolic Acid, Dithiodiglycolic Acid and Ammonia in Indoor Air of a Beauty Salon: Daisuke OIKAWA, et al. Kankyo Research Co., Ltd.—

Colorimetric monitoring of formaldehyde in indoor environment using built-in camera on mobile phone

ABSTRACT A simple monitoring system of indoor air pollution is proposed by integrating a novel colorimetric detector of formaldehyde (HCHO) and a function of a built-in camera on mobile phone. The colorimetric detector employs a solid phase colorimetric reagent made from 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, ZnO, KIO4 and agar, and changes colour from white to purple by exposure to HCHO gas. The degree of colour changes expressed in Red, Green and Blue model model responded to the HCHO concentration levels both in air and from building materials. Limit of quantitation of the detector with 24 h-exposure resulted in 0.011 mg/m3 of air concentration which meets a requirement of methodology to detect indoor air quality guideline level of HCHO set by World Health Organization. The detector is also applicable to classify HCHO-emitting materials at least into Type 1, whose emission flux is greater than 120 μg/m2/h, and others. Then, variation of the acquired photo images was investigated by using various mobile phones and changing conditions of photography. As a result, the calibration of the measured colour intensity with a colour standard reduced the variation of the results and gave a significant output when the auto-focused images were taken under the condition of common indoor environment.

Simultaneous and multi-point measurement of ammonia emanating from human skin surface for the estimation of whole body dermal emission rate

Ammonia is one of the members of odor gases and a possible source of odor in indoor environment. However, little has been known on the actual emission rate of ammonia from the human skin surface. Then, this study aimed to estimate the whole-body dermal emission rate of ammonia by simultaneous and multi-point measurement of emission fluxes of ammonia employing a passive flux sampler - ion chromatography system. Firstly, the emission fluxes of ammonia were non-invasively measured for ten volunteers at 13 sampling positions set in 13 anatomical regions classified by Kurazumi et al. The measured emission fluxes were then converted to partial emission rates using the surface body areas estimated by weights and heights of volunteers and partial rates of 13 body regions. Subsequent summation of the partial emission rates provided the whole body dermal emission rate of ammonia. The results ranged from 2.9 to 12mgh-1 with an average of 5.9±3.2mgh-1 per person for the ten healthy young volunteers. The values were much greater than those from human breath, and thus the dermal emission of ammonia was found more significant odor source than the breath exhalation in indoor environment.

Measurement of 2-nonenal and diacetyl emanating from human skin surface employing passive flux sampler-GCMS system

It is commonly said elderly persons have a characteristic body odor, and, at present, two chemical compounds have been found to vary with age in male Japanese: 2-nonenal and diacetyl. To investigate dermal emission flux of the ageing odor related compounds, we have developed a non-invasive sampling device based on a concept of passive flux sampler (PFS). The sampler was placed on the skin surface to create a headspace, and the gases emanating from skin moved toward a disk-type adsorbent. The trapped gases were then extracted with dichloromethane and determined by GCMS. The PFS was practically applied to healthy volunteers covering a wide range of age. Since emission fluxes of both compounds remarkably varied with sampling position, the nape of the neck was fixed as regular sampling position where there are dense networks of both sebaceous and eccrine glands which are potential sources of both compounds. The emission flux of 2-nonenal increased with age for both male and female volunteers, whilst the flux of diacetyl showed highest in 30s and decreased over 40s. Although diacetyl has been known as a middle-aged male odor, this study showed the odor caused by diacetyl was not specific to male.

Detection of tobacco smoke emanating from human skin surface of smokers employing passive flux sampler – GCMS system

Cigarette smoking is a significant risk factor for higher incidences of numerous adverse health consequences. Related health disorders are also found in non-smokers exposed to secondhand smoke (SHS). To investigate the influence of cigarette smoking and exposure to SHS on the composition of human skin gas, a trace biogas emanating from human skin, dermal emissions of volatile compounds were semi-quantitatively measured for volunteers who smoke a cigarette and those exposed to SHS. This was performed using a passive flux sampler (PFS) coupled with gas chromatography mass spectrometry (GCMS). Numerous chemicals were detected, including acetaldehyde, toluene, 3-methyl furan (3-MF), 2,5-dimethyl furan (2,5-DMF), 3-ethenyl pyridine (3-EP), and nicotine, in the samples collected from the smokers after a smoking event, and a remarkable increase in the amount of chemicals collected was observed just after smoking. These chemicals were also found in the samples collected from volunteers exposed to SHS. Assessment of current smoking status is important for managing the negative effects of active and passive smoking, and for the development of public health policy. The tobacco specific chemicals such as 3-MF, 2,5-DMF, 3-EP, and nicotine, emanating from human skin surfaces, represent a potential non-invasive biomarker for monitoring current smoking status of active and passive smokers after establishing a more quantitative procedure.

Photocatalytic degradation of atmospheric fine particulate matter (PM2.5) collected on TiO2 supporting quartz fibre filter

ABSTRACT Carbonaceous constituents in fine particulate matter (PM2.5) are often associated with adverse health effects in humans. Although air filtration technology is widely used for preventing exposure to PM2.5, the trapped PM2.5 still has hazardous property if not treated subsequently. Thus, this study aimed to realise detoxification of PM2.5 with a photocatalytic decomposition of carbonaceous compounds in PM2.5 samples collected on a quartz fibre filter coated with titanium dioxide (TiO2). The mass of PM2.5 gradually decreased with time during the UV irradiation with a significant release of carbon dioxide (CO2) as a product. The analysis of organic carbon (OC) and elemental carbon (EC) using a thermal/optical carbon analyser following the IMPROVE protocol showed that carbonaceous constituents such as OC1, OC2, OC3, OC4, and EC1 fractions were successfully decomposed by UV-irradiated TiO2, whereas EC2 and EC4 fractions were inert to the photocatalysis. However, a majority of the carbon content, approximately 92% of the total carbon, was reduced by the proposed method. This shows that the photon-induced TiO2 potentially reduces the hazardous effects of PM2.5. GRAPHICAL ABSTRACT

Disasters and Their Impacts on Air Quality in the Human Living Environment

Although clean air is one of the most important necessities for human life and health, the risk of natural disasters causing air pollution that reduces or inhibits “resiliency” of the victims and communities has not been well understood. This chapter examines the secondary disaster of the air pollution events induced by the Great East Japan Earthquake and subsequent tsunami in 2011—such as the release and diffusion of radioactive substances from the severely damaged Fukushima Daiichi nuclear power plant, chemical contamination in indoor air of temporary housing built (so-called Sick House Syndrome), and the scattering of asbestos fibers liberated by the quake and tsunami. Air pollution is something that often cannot be seen until severe impacts are noticed later. The paper then describes the importance of air quality monitoring by scientific means and sharing knowledge for risk recognition and immediate pollution controls based on the identification of source of problems for risk reduction, in the context of resilience.

Effect of Coal Fly Ash Leachate on the Bioluminescence Intensity of Vibrio fischeri

Coal fly ash is a residue of coal-fired thermoelectric power plants (TPPs) and is mostly dumped in ash ponds or landfill sites, even though it potentially contains significant amounts of water-soluble hazardous contaminants. Bioassay using the bioluminescent bacterium *Vibrio fischeri* is known to be applicable for assessing the short-term and sublethal toxicity of complex mixtures without the need for precise chemical characterization. However, this type of bioassay is potentially adversely influenced by the pH-induced protein denaturation of cells. Because coal fly ash leachates often have alkaline or acidic properties, when applying the *V. fischeri*-based bioassay to the samples, we need to know potential effect of the leachates on the bioluminescence of the bacteria. This study accordingly aimed to investigate the feasibility of applying the *V. fischeri* bioassay to coal fly ash leachate as a screening method. Fly ash samples were collected from 12 TPPs located in three East European countries: Bulgaria, Greece, and Serbia. The fly ash samples were prepared in sterilized distilled water by ultrasonic extraction and filtration using 0.45-MGRmPHI membrane filters. The filtrates were then mixed with a solution of the test bacterium. The bioluminescence intensity was measured using a luminometer. The results showed the ostensible influence of pH on bioluminescence intensity pronounced when following the typical protocol using a 5.0-g/L solid:liquid ratio. Accordingly, the pH of water extracts should be adjusted to within a range of 6 to 9 by dilution to observe the inhibition of bioluminescence by coal fly ash leachate as the objective endpoint.