Indoor Air Control by Microplasma

Abstract

Sick-Building Syndrome (SBS) has become an environmental issue worldwide in recent decades (P. Burge, 2004). Much research on this syndrome has been carried out. Generally, it is known that since buildings became more airtight for improvement of air-conditioning and heating, the effect of Volatile Organic Compounds (VOCs) diffusions from building materials has increased, causing many symptoms of SBS. Control of these indoor air pollutants is necessary to maintain Indoor Air Quality (IAQ). Recently, Indoor Air Quality (IAQ) is recognized as an important factor of home and building construction (P. Wolkoff, G. D.Nielsen, 2001). Formaldehyde (HCHO) is one of the most common indoor VOCs. This substance is emitted from resins, plastics and often building materials, such as plywood, chipboard, and paneling, and is one of the main causes of SBS (H. Yoshino, 2004). Indoor air contaminants which worsen IAQ are characterized by the presence of not only VOCs, but also of fungus and bacteria, various malodorous substances and Environmental Tobacco Smoke (ETS) etc. VOCs such as formaldehyde (HCHO) are well known as a cause of sick building syndrome (A. Seki et al., 2007). Indoor air concentration of HCHO is regulated at 0.08 ppm by Ministry of Health, Labor and Welfare (MHLW) in Japan. Decompositions of VOCs by nonthermal plasma technique have been researched recently (A. Koutsospyros et al., 2004; D. Li et al., 2002; K. N. Faungnawakji et al., 2004; K. Urashima and J. S. Chang, 2000; T. Oda et al., 2004; Y.-H. Song et al., 2002). In addition, infective diseases such as new influenza strains caused by pathogenic organisms have been spread worldwide. Recently this causes serious problems in schools and a lack of vaccines in many countries. In this context, home appliance manufactures have developed air purifiers for the market in Japan, but not in the market worldwide (Sharp, Panasonic, Daikin). Research on air purification; both odor treatment and bacteria, viruses treatment based on the nonthermal plasma technique has also been intensively studied in universities as well as by home appliance manufacturers (A. Sakudo and H. Shintani, 2010; F. J. Trompeter et al., 2002; H. Ghomi et al., 2005; K. Kitano et al., 2006; M. Laroussi et al., 2004; M. Nagatsu et al., 2003; T. C. Montie et al., 2000, N. Hayashi et al., 2006; N. S. Panikov et al., 2002, T. Ito et al., 1992.) These nonthermal plasma techniques were carried out with rather “high voltage” region (5-15 kV, sometimes more than 20 kV)( A. Mizuno et al., 1995). It is expected that they can be alternatives to other simple plasma techniques to purify indoor air. In this chapter, a technique for indoor air control by microplasma will be introduced (K. Shimizu et al., 2008, 2009, and 2010 a, b, and c).