Reducing Indoor Air Pollutants Through Biotechnology - Biotechnologies and Biomimetics for Civil Engineering - page 179

influence the extremely low normal airborne concentrations of VOCs in most
indoor environments (e.g. Llewellyn and Dixon 2011 ; Soreanu et al. 2013 ). Simple
potted plant based-biolfiltration systems, nonetheless, clearly have the potential to
be effective in the built environment. In a large study of university offices, Wood
et al. ( 2006 ) demonstrated that the presence of an indoor plant was associated with
significant reductions in ambient total volatile organic compound (TVOC) levels.
Unfortunately, there has been little subsequent research performed under field
conditions to test the efficacy of passive potted plant systems, and possibly as a result
of this, active, and other biofilter type systems have dominated the research in this
field in more recent years.
8.4 Indoor Air Pollutants
8.4.1 Volatile Organic Compounds
Of the different types of indoor air pollutants, VOCs have received the great
majority of research attention. Even at imperceptible levels (\200 ppb), mixtures
of VOCs are thought to cause symptoms of 'sick-building-syndrome' or 'building-
related-illness' (Jaakola et al. 2007 ; Liu et al. 2007 ; Epstein 2008 ).
VOC is a general term encompassing various classes of carbon-containing, low
boiling-point compounds that are gaseous at room temperature. The combination
of VOC sources within buildings result in the occupant typically being exposed to
50-300 different VOCs, at levels usually in the lg/m -3 (or ppbv) range (Bernstein
et al. 2008b ). VOCs have been linked to an array of adverse health responses. Even
at levels well below human perception, VOCs can contribute to symptoms that
resemble those of SBS, and at high levels have the potential to be hematotoxic,
neurotoxic, leukemogenic and, in the case of some compounds, such as benzene,
also carcinogenic (Vaughan et al. 1986 ; Wallace 2001 ; Wolkoff and Nielsen
2001 ). The review of Guieysse et al. ( 2008 ) provides a detailed review of the
health effects of indoor VOCs. Whilst there is some debate as to the magnitude of
the health effects of lg/m -3 concentrations of VOCs on building occupants
(Wolkoff 2013 ), and how those effects vary with different VOC mixtures and
relative concentrations, it is generally accepted that exposure to VOCs indoors has
significant negative health outcomes.
Apart from the occasional report documenting trivial VOC removal capacity by
plant tissues (Kim et al. 2008 , Treesubsuntorn and Thiravetyan 2012 ), or bacteria
on the leaf surface or phyllosphere (Sandhu et al. 2007 ), the quantitative biore-
mediation of VOCs is now generally accepted to primarily occur through root zone
microbial activity (Wood et al. 2002 ; Orwell et al. 2004 ; Kim et al. 2008 ), where the
VOCs are used directly as carbon sources by microorganisms. One of the primary
challenges for the biological removal of VOCs is that alone, their concentrations in
indoor air are probably insufficient to sustain microbial growth (Guieyesse et al.
2008 ). Thus major efforts in the development of biological processes to ameliorate