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lung fibrosis - (ATSDR
2013b
). The latency period since the exposure and the
manifestation of the asbestos-related disease is between 20 and 50 years (Bolton
et al.
2002
). Shorter latency periods may be considered when exposure occurs
during home maintenance and renovation involving asbestos-containing products,
since there is evidence that it increases the incidence of malignant mesothelioma
(Olsen et al.
2011
).
Iceland was the first country to ban most forms of asbestos in 1983 and, since
then, efforts have been made to ban asbestos-containing products elsewhere
(Haynes
2010
). Commercialisation and use of asbestos products were banned in the
European Union in
1999
(Directive 99/77/EEC) and, the extraction, manufacture,
and processing of asbestos-containing products were banned in
2003
(Directive
2003/18/EC). Manufacture, importation, processing, and distribution of most
asbestos-containing products were banned in United States in 1989, but the regu-
lation was overturn in 1991. Nowadays, asbestos-containing products are not totally
banned in USA (US EPA
2013b
). After the World Trade Centre disaster in 2001
and the resulting exposure to asbestos, especially among cleanup workers and
volunteers, the regulatory policies on asbestos in the United States were recon-
sidered (Lange
2001
). A limit value of 0.1 fibres/cm
3
for the protection of workers
was established in Europe (Directive
2009
/148/EC), which is the same limit in
force in USA. Indoor concentrations of asbestos in different microenvironments are
usually below that limit, even when refurbishment is performed (see Fig.
1
).
2.2 Carbon Monoxide
Carbon monoxide (CO) is a colourless, odourless and tasteless toxic gas. The
toxicity of CO is mainly related with its reactivity with haemoglobin to form
carboxihaemoglobin (COHb), which decreases the oxygen-carrying capacity of the
blood. Exposure to dangerous levels of CO occurs mainly indoors, where CO
lethal levels lead each year to a number of deaths worldwide (Raub et al.
2000
).
The main indoor CO source is the incomplete combustion of carbon-containing
fuels used for cooking and heating purposes. Poorly adjusted and maintained or
unvented boilers, stoves, and heaters can be a significant source of CO indoors, as
well as tobacco smoke. High indoor CO levels may also be found due to the
contribution of vehicle-exhaust outdoor air masses coming from parking areas or
garages (US EPA
2013c
). CO is also emitted in low quantities by the endogenous
metabolism of the building occupants (Wu and Wang
2005
). In the absence
of indoor sources, indoor concentrations of CO can be lower than outdoors.
Dangerous levels of CO may be reached indoors when malfunctioning or unvented
combustion devices are used (Jones
1999
).
Natural background concentrations of CO in remote areas were reported to be
between 0.06 and 0.14 mg/m
3
, while in traffic-affected areas and poorly ventilated
indoor spaces CO may range between 20 and 60 mg/m
3
(Georgoulis et al.
2002
).
A recent review reported that typical concentrations of CO in public buildings
