Environmental Engineering Reference
In-Depth Information
with physiochemical processes (Lee et al. 2013 ). With this strong background,
biofilters are beginning to emerge as an accepted alternative to ventilation for the
maintenance of IAQ.
Whilst it is usually assumed that active biofilters will remove higher quantities
of air pollutants than passive systems due to the increased rate of airflow over the
biodegradative surfaces (e.g. Soreanu et al. 2013 ), there appears to be no literature
comparing an active system to an otherwise identical passive arrangement, and
thus there is no empirical evidence to show that actively increasing the airflow to a
system increases biodegradation over simple diffusion. Also, the potential gener-
ation of CO 2 from substrate microorganism respiration, and the emission of
microbial particles are other issues that have been inadequately addressed in the
literature. Clearly, there is a need for greater research on the correlation between
the rate of airflow and all types of air quality for active IAQ bioremediation
systems.
8.8 Health Benefits of Indoor Plants Unrelated
to Air Quality
Indoor plants have also been shown to yield directly measurable benefits to the
health and wellbeing of building occupants. Fjeld et al. ( 1998 , 2000) found that
staff sick leave was reduced by over 60 % when indoor plants were installed. They
also found less sick leave among school children with plants in their classroom,
and that staff with plants in offices showed significantly fewer health and dis-
comfort problems, including 37 % less coughing, 30 % less fatigue and 23 % in
symptoms such as headaches, sore eyes, nose or throat, 'heavy-headedness' or
lowered concentration. Studies by Lohr et al. ( 1996 ) also showed productivity
gains and reductions in perceptions of pain and discomfort when plants were
present. A Texan survey with over 400 respondents (Dravigne et al. 2008 ) found
that job satisfaction rose significantly on all 10 criteria tested among staff with
indoor plants and that they preferred them to planted window views.
The effect of indoor plants on psychological health may be due to a surrogate
effect akin to exposure to 'nature', with the clinical effect described as 'attention
restoration theory' (e.g. see Bringslimark et al. 2009 ). The magnitude of the
psychological benefits of botanical material may be proportional to the volume of
plant material in an indoor space, presence in the line of sight of an occupant and
duration of exposure. Whist the magnitude of the effects of plants on psychological
health are subject to some controversy (Brigslimark et al. 2009 ), the bulk of the
literature shows a quantifiable effect.
As some of the current biotechnological approaches to botanical air cleaning,
notably green walls, are often associated with a substantial increase in the amount
of plant material in a building (Fig. 8.2 ), the potential exists that these systems
could provide corollary benefits to psychological health and worker productivity
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