Civil Engineering Reference
In-Depth Information
In the study performed by de Blas et al. (
2012
) in an urban building, benzene
was found to have both indoor and outdoor origin. Some benzene peaks were
related to outdoor traffic and industrial emissions, others were related to indoor
activities, but some peaks occurred during weekends, when there was no activity in
the building, emitted by building materials or products used in the refurbishment
of the building. A recent review also reported that a high benzene indoor
concentration may be found were in public buildings located nearby traffic sources
or when strong indoor benzene sources are present, such as building materials
(Kolarik et al.
2012
).
2.7.2 Formaldehyde
Formaldehyde, CH
2
O, is the simplest and the most widespread aldehyde found in
the environment. At room temperature, formaldehyde is a colourless gas with a
characteristic pungent and irritating odour. Inhalation is the main exposure path,
causing irritation of the respiratory tract and eyes. Dermal exposure can also result
in skin irritation (Jones
1999
). Formaldehyde is classified as carcinogenic to
humans by the IARC, since it causes nasopharyngeal cancer in humans. New
epidemiological findings concluded that occupational exposure to formaldehyde
causes leukaemia, but there is limited evidence for sinonasal cancer.
The main use of formaldehyde is the fabrication of urea-formaldehyde, a
component of resins added to foam insulation materials and to adhesives used to
manufacture particleboards, furniture or plywood. The emission rate of formal-
dehyde from those materials has been reported to increase with temperature, wood
moisture content, humidity and the age of the material (Theodore and Theodore
2009
). Also, many consumer products, ornaments and appliances contain form-
aldehyde: antiseptics, cleaning agents, carpets and permanent press fabrics, ciga-
rettes, cosmetics, fertilisers, wiring and appliances, paints and varnishes and
preserved foods (ATSDR
2013b
).
Apart from building materials and household products, other additional sources
may contribute to indoor formaldehyde such as outdoor air, indoor chemical
reactions, candles, cooking, gas heaters and so on (Salthammer et al.
2010
). Main
sources of formaldehyde in ambient air are combustion processes, such as
emissions from motor vehicles, power plants and incinerators (ATSDR
2013b
).
Destaillats et al. (
2006
) reported that in the presence of ozone, formaldehyde is the
major oxidation product of cleaners, degreasers, and fresheners, emitting a variety
of VOCs such as terpenoids, alcohols and esters. Small amounts of formaldehyde
may be naturally emitted by plants, animals and humans (ATSDR
2013b
).
Figure
7
shows indoor and outdoor formaldehyde concentration values from
selected studies. Indoor concentrations of formaldehyde are generally higher than
outdoor ones. Concentrations at residences are higher with respect to buildings
used as workplaces (Jurvelin et al.
2001
; Geiss et al.
2011
), due to the many
sources at homes, and/or a better ventilation in workplaces. From the data in
