Civil Engineering Reference
In-Depth Information
are gases (Wu et al.
2011
) and particulates (Wheeler et al.
2011
). The distribution
of both is governed by the general airflow field in interaction with local sources
and sinks. In addition to that, gravity will cause particulates to settle. This effect is
proportional to the size of the particulate (Cuccia et al.
2013
), with the smallest
particulates acting more or less as gases.
Gases can be both inorganic (Pacheco Torgal
2012
) and organic (Hun et al.
2010
) in nature, while particulates usually have complex chemical compositions
and often contain biological agents such as bacteria and viruses (Chang and Chou
2011
). In both categories, the abundant presence of other pollutants and boundary
conditions such as temperature and humidity levels can affect the stability of the
pollutants (Weschler and Nazaroff
2008
) and trigger secondary pollutant formation
in the air itself (Corsi et al.
2007
; Huang et al.
2011
).
1.1 Effects
The mostly adverse effects of airborne pollutants have been the topic of numerous
studies over the last decades. They can be divided into three main categories:
effects on health, effects on productivity and effects on comfort. With respect to
health effects, there is a large grey zone as to what effects should be included or
not. In the overview of the reported effects below, all effects that relate to short-
term direct effects, such as headache, dry or burning sensation, usually grouped
under the term 'sick building syndrome', are listed as comfort effects.
1.1.1 Health Effects
WHO has prioritized a number of inadequate housing conditions based on their
associated burden of disease, expressed in disability-adjusted life years (DALYs)
(Braubach and Jacobs
2011
), including airborne agents such as dampness, radon,
second-hand smoke, carbon monoxide and formaldehyde. Ventilation rates are
negatively correlated with the prevalence of inflammation, respiratory infections,
asthma symptoms, short-term sick leave and allergic manifestations (Sundell et al.
2011
; Wargocki et al.
2002b
). In these studies, ventilation rate is used as a proxy
for overall pollutant concentration. For a discussion on epidemiological research
focused on the health effects of exposure to specific pollutants, ''
A Multiple-Case
1.1.2 Productivity Effects
A series of independent studies has shown a positive relation between student's
academic performance, across different lesson subjects, and the ventilation rate in
the class room, both on intervention studies (Bakó-Biró et al.
2012
; Wargocki and
