Indoor Air Pollution - Air Pollution and Global Warming: History, Science, and Solutions - page 207

Chapter 9

Indoor Air Pollution

People spend most of their time indoors, so the compo-
sition and quality of indoor air has a significant impact
on human health. Because people's time is often divided
between home and work, it is important to examine air
quality in both residences and workplaces. Sources of
indoor air pollution include outdoor air that infiltrates
indoors and indoor emissions. Outdoor air contains the
constituents of smog, but some of these constituents dis-
sipate quickly indoors because of the lack of UV radi-
ation to regenerate them indoors. Major indoor sources
of pollution include stoves, heaters, carpets, fireplaces,
tobacco smoke, motor vehicle exhaust from garages,
building materials, and insulation. In developing coun-
tries, major sources of indoor air pollution include the
products of solid biofuel and coal combustion for home
heating and cooking. Such pollution is responsible for
significant premature mortality worldwide. Whereas
indoor air pollution is often regulated in workplaces,
it is not regulated in residences. In this chapter, charac-
teristics, sources, and regulation of indoor air pollution
are discussed.

about 79 percent of their time indoors, and those in
rural areas spent about 65 percent of their time indoors
(Smith, 1993). Because people breathe indoor air more
than outdoor air, an examination of indoor air is war-
ranted. Nearly 1.6 million people worldwide die each
year prematurely from indoor air pollution (not includ-
ing smoking), making it one of the leading causes of
death worldwide (World Health Organization (WHO),
2005). Most of these deaths are due to indoor burning
of solid biofuels and coal for home heating and cooking
with inefficient cook stoves and heaters.
Table 9.1 identifies major pollutants in indoor air and
their primary sources. Many of the pollutant gases in
indoor air are also found in outdoor air. Outdoor pol-
lutants enter indoor air by infiltration, natural ventila-
tion, and forced ventilation. Infiltration is natural air
exchange through cracks and leaks, such as through
door and window frames, chimneys, exhaust vents,
ducts, plumbing passages, and electrical outlets. Natu-
ral ventilation is air exchange resulting from the open-
ing or closing of windows or doors to enhance the cir-
culation of air. Forced ventilation is the air exchange
resulting from the use of whole house fans or blowers
(Masters, 1998). Next, the pollutants in Table 9.1 are
discussed briefly.

9.1. Pollutants in Indoor Air
and Their Sources
Throughout the world, people spend most of their time
indoors. One study found that, in the United States,
about 89 percent of time was spent indoors, 6 percent
wasspent in vehicles, and 5 percent was spent out-
doors (Robinson et al., 1991). A study of less devel-
oped countries showed that people in urban areas spent

9.1.1. Carbon Dioxide
Carbon dioxide [CO 2 (g)], which is present in back-
ground air, is also produced indoors from breathing and
the burning of wood, coal, oil, and gas. It does not pose