to be associated with a high asthma hazard index
[45]. Experiments performed by Petrick et al. indicate that SOAs (in this case ultrafine particles) are
formed from heterogeneous reactions of surfacesorbed nicotine with ozone, rather than through a
homogeneous reaction entirely in the gas phase.
This heterogeneous reaction is the major source of
SOA from ozonolysis of secondhand tobacco
smoke. In addition, their study shows that the
peak formation of SOA is at low humidity
levels [46].
Indoor Air Quality and Health
Sick Building Syndrome
Sick building syndrome has been the subject of a
lot of research the recent years, as there seems to
be an increase in cases of SBS. There is no agreement on the exact definition of SBS, as it is associated with a wide range of symptoms and
sources. Symptoms typically occur when people
spend long periods of time in an unhealthy indoor
environment, such as in an airtight office building
or school [47]. SBS is mainly linked to poor IAQ
and the associated problem of poor ventilation.
Other contributing factors include noise, stress, a
monotonous work environment, temperature,
humidity, and biological sources including mold
and fungi. Noise in buildings has been associated
with eye pain, nausea, and skin dryness. A lack of
proper lighting can cause dizziness and malaise
[48]. Furthermore, the risk of SBS is larger for
smokers and for people who suffer from asthma or
allergy [47].
Despite these many contributing factors, IAQ
is the major contributor to SBS, and high levels of
pollutants including NO x , PM, CO 2 , and VOCs
have been shown to increase the risk of SBS
[1, 49, 50]. This is supported by the fact that an
increase in ventilation rate leads to fewer cases of
symptoms related to SBS, such as fatigue, headache, and throat irritation. Another important
aspect of SBS is the negative effect it has on
productivity. This is especially relevant for working spaces, as SBS can result in loss of work [47,
50]. A study found that the most optimal temperature for work productivity is 21–22
C [51].
Improving IAQ to reduce SBS can help companies due to increased productivity. For example,
the benefits of implementing a particle filter
greatly outweigh the installation and running
costs [52]. This should encourage companies to
implement similar solutions.
Asthma and Allergy
There has been a substantial increase in respiratory illnesses and asthma over the last generation,
especially in industrialized countries. Some
researchers link this trend to the indoor environment, where numerous pollutants can be found.
Variables that negatively affect the human respiratory system include carbon monoxide, tobacco
smoke, allergens, mold, dampness, humidity, and
particulate matter. Prevention of carbon monoxide
pollution can be affected by the correct installation and venting of gas appliances, while tobacco
smoke can be eliminated by nonsmoking indoors.
Allergens from house dust mites and cats have
proven to exacerbate asthma in individuals
already sensitized to the given allergen
[53]. Thus, an allergy patient will be at higher
risk of developing asthma when exposed to the
allergen. House dust mites are found in carpets,
bedding, and mattresses, where the allergens are
released by, e.g., vacuuming (without a high efficiency filter), general cleaning, and other indoor
activities. The amount of house dust mite allergens can be minimized by hot washing of bedding
(>55
C) [54], use of feather-filled pillows [55],
and by encasing bedding and mattresses in impermeable material [56], as well as having noncarpeted flooring in the home [57]. However,
these measures have not shown clinical improvement in patients already suffering from asthma
[58]. The majority of pet allergens originate
from cats (in UK homes, there are 11.1 million
cats and 8.9 million dogs [59]), as cat allergens are
respirable (<5 mm), whereas 80% of dog allergens
are nonrespirable due to their large size (>5 mm)
[60]. Data shows that asthmatic individuals sensitive to cat allergens will experience worsening of
their asthma when exposed to cats [53]. There is
insufficient evidence to determine if exposure to
cat allergens will cause asthma development in
healthy subjects [53]. Another pollutant that has
146
Indoor Air Quality: Status and Standards
[45]. Experiments performed by Petrick et al. indicate that SOAs (in this case ultrafine particles) are
formed from heterogeneous reactions of surfacesorbed nicotine with ozone, rather than through a
homogeneous reaction entirely in the gas phase.
This heterogeneous reaction is the major source of
SOA from ozonolysis of secondhand tobacco
smoke. In addition, their study shows that the
peak formation of SOA is at low humidity
levels [46].
Indoor Air Quality and Health
Sick Building Syndrome
Sick building syndrome has been the subject of a
lot of research the recent years, as there seems to
be an increase in cases of SBS. There is no agreement on the exact definition of SBS, as it is associated with a wide range of symptoms and
sources. Symptoms typically occur when people
spend long periods of time in an unhealthy indoor
environment, such as in an airtight office building
or school [47]. SBS is mainly linked to poor IAQ
and the associated problem of poor ventilation.
Other contributing factors include noise, stress, a
monotonous work environment, temperature,
humidity, and biological sources including mold
and fungi. Noise in buildings has been associated
with eye pain, nausea, and skin dryness. A lack of
proper lighting can cause dizziness and malaise
[48]. Furthermore, the risk of SBS is larger for
smokers and for people who suffer from asthma or
allergy [47].
Despite these many contributing factors, IAQ
is the major contributor to SBS, and high levels of
pollutants including NO x , PM, CO 2 , and VOCs
have been shown to increase the risk of SBS
[1, 49, 50]. This is supported by the fact that an
increase in ventilation rate leads to fewer cases of
symptoms related to SBS, such as fatigue, headache, and throat irritation. Another important
aspect of SBS is the negative effect it has on
productivity. This is especially relevant for working spaces, as SBS can result in loss of work [47,
50]. A study found that the most optimal temperature for work productivity is 21–22
C [51].
Improving IAQ to reduce SBS can help companies due to increased productivity. For example,
the benefits of implementing a particle filter
greatly outweigh the installation and running
costs [52]. This should encourage companies to
implement similar solutions.
Asthma and Allergy
There has been a substantial increase in respiratory illnesses and asthma over the last generation,
especially in industrialized countries. Some
researchers link this trend to the indoor environment, where numerous pollutants can be found.
Variables that negatively affect the human respiratory system include carbon monoxide, tobacco
smoke, allergens, mold, dampness, humidity, and
particulate matter. Prevention of carbon monoxide
pollution can be affected by the correct installation and venting of gas appliances, while tobacco
smoke can be eliminated by nonsmoking indoors.
Allergens from house dust mites and cats have
proven to exacerbate asthma in individuals
already sensitized to the given allergen
[53]. Thus, an allergy patient will be at higher
risk of developing asthma when exposed to the
allergen. House dust mites are found in carpets,
bedding, and mattresses, where the allergens are
released by, e.g., vacuuming (without a high efficiency filter), general cleaning, and other indoor
activities. The amount of house dust mite allergens can be minimized by hot washing of bedding
(>55
C) [54], use of feather-filled pillows [55],
and by encasing bedding and mattresses in impermeable material [56], as well as having noncarpeted flooring in the home [57]. However,
these measures have not shown clinical improvement in patients already suffering from asthma
[58]. The majority of pet allergens originate
from cats (in UK homes, there are 11.1 million
cats and 8.9 million dogs [59]), as cat allergens are
respirable (<5 mm), whereas 80% of dog allergens
are nonrespirable due to their large size (>5 mm)
[60]. Data shows that asthmatic individuals sensitive to cat allergens will experience worsening of
their asthma when exposed to cats [53]. There is
insufficient evidence to determine if exposure to
cat allergens will cause asthma development in
healthy subjects [53]. Another pollutant that has
146
Indoor Air Quality: Status and Standards