Civil Engineering Reference
In-Depth Information
2 Main Indoor Air Pollutants, Toxicity and Sources
In order to protect human health from the adverse effects caused by pollutants
commonly present in indoor air WHO has developed its WHO guidelines for IAQ.
These guidelines do not include workplaces, where specific sources can be present.
Therefore, occupational exposure is not assessed. The first series of the guidelines
for IAQ: dampness and mould (WHO
2009
) is focused on avoiding microbial and
biological indoor pollution. The second series is focused on selected pollutants
(WHO
2010
) which have indoor sources and pose a risk for the health of the
building occupants: CO, NO
2
, PM, polycyclic aromatic hydrocarbons (PAHs,
especially benzo-[a]-pyrene), radon, and some VOCs (benzene, formaldehyde,
naphthalene, trichloroethylene, and tetrachloroethylene).
Apart from the indoor pollutants included on the second guideline, WHO
working group stated that current evidence was uncertain or not sufficient for
guidelines on the following pollutants: acetaldehyde, asbestos, biocides, pesti-
cides, flame retardants, glycol ethers, hexane, nitric oxide (NO), ozone, phthalates,
styrene, toluene and xylenes. Asbestos is included in this chapter for two reasons:
it was widely used in construction, now requiring building refurbishments, and the
International Agency for Research on Cancer (IARC) classified asbestos as a
carcinogen for humans.
Indoor pollutants covered in this chapter are shown in Table
2
, together with
their WHO guideline values and a summary of their effects on human health.
Guideline and reference values are established depending on toxicological,
epidemiological, and statistical criteria, considering short-term and long-term
effects on human health. Quantitative guideline values for dampness and mould
are not provided by WHO because the response to dampness, microbial exposure,
and health effects cannot be precisely quantified.
Other indoor pollutants have been considered by researchers and regulatory
programs. For example, environmental tobacco smoke (ETS) is considered one of
the major contributors to indoor air pollution, but it has been eliminated from most
indoor spaces, so it is not included in WHO guidelines for IAQ. Most scientific
literature considers ETS as a pollutant itself, but it is a mixture of multiple
components such as CO, nitrogen oxides, sulphur oxides, VOCs, PAHs, ammonia,
and PM (Rando et al.
1997
). Out of these, more than 20 substances are known to
be carcinogens (Hecht
1999
).
Some indoor pollutants, namely CO, PM, SO
2
,NO
2
,O
3
, and VOCs are both
indoor and outdoor pollutants. Nevertheless, due to infiltration, accumulation, and
indoor sources their indoor concentration could be higher than outdoors. Other
pollutants, such as radon, asbestos, and some biologic pollutants can be considered
exclusively indoor pollutants. Moulds and bacteria may emit microbial volatile
organic compounds are (MVOCs) when growing on building materials and, hence,
they are considered indoor pollutants and their indoor concentration is usually
higher indoors (Sahlberg et al.
2013
). Consequently, some MVOCs may be used as
markers
of
dampness
and
mould
such
as
3-methylfuran,
emitted
by
fungi
