Geoscience Reference
In-Depth Information
SBS may alternatively be caused by exposure to
many pollutants in low doses simultaneously. This con-
dition is referred to as
multiple chemical sensitivity
(MCS)
. People who are exposed over a long period
of time to low levels of many chemicals due to poor
ventilation in an office building can have reactions that
people without MCS usually tolerate. Statistically, one-
third of people working in a sealed building may be sen-
sitive to one or more common chemicals. Triggers for
MCS include tobacco smoke, perfume, traffic exhaust,
nail polish remover, newspaper ink, hair spray, paint
thinner, paint, insecticide, artificial colors and sweet-
eners, carpeting, adhesive tape, flame retardant, felt-tip
pens, and chlorine (MedicineNet, n.d.).
residences. In addition, indoor and some outdoor smok-
ing regulations have been enacted in more than 100
countries (WHO, 2009a). In this section, indoor regu-
lation of air pollution is briefly discussed, with a focus
on U.S. regulations as an example.
In the United States, NAAQS control outdoor air pol-
lutants only. No regulations control air pollution con-
centrations in indoor residences. In 1994, California
wasthe first state to ban smoking in indoor workplaces.
However, as of 2011, smoking was still legal in Califor-
nia Indian casinos, resulting in high concentrations of
pollution particles in these venues (Jiang et al., 2011).
Aside from smoking regulations, regulatory stan-
dards for individual pollutant concentrations in indoor
workplaces are set by the
Occupational Safety and
Health Administration (OSHA)
,which obtains rec-
ommendations for standards from another govern-
ment agency, the
National Institute for Occupational
Safety and Health (NIOSH)
, and an independent pro-
fessional society, the
American Conference of Gov-
ernmental Industrial Hygienists (ACGIH)
.OSHA
and NIOSH were created by the Occupational Safety
and Health Act in 1970. OSHA, an agency within the
U.S. Department of Labor, is responsible for setting
and enforcing workplace standards, whereas NIOSH,
an agency within the U.S. Department of Health and
Human Services, is responsible for researching work-
place health issues. ACGIH's primary mission is to pro-
mulgate workplace safety standards. Workplace regu-
lations apply to public buildings and schools, which are
also considered workplaces.
NIOSH recommends
permissible exposure limits
(PELs),
short-term exposure limits
(STELs), and
ceil-
ing concentrations
.APEListhe maximum allow-
able concentration of a pollutant in an indoor work-
place over an 8-hour period during a day. A STEL is
the maximum allowable concentration of a pollutant
overa15-minute period. A ceiling concentration is a
concentration that may never be exceeded. ACGIH sets
8-hour
time-weighted average threshold limit val-
ues
(TWA-TLVs), which are similar to PELs. For most
pollutants, PELs and TWA-TLVs are the same. When
differences occur, they are small.
Indoor standards exist for more than 150 compounds.
Table 9.4 compares indoor standards with outdoor
standards for four compounds. For ozone and carbon
monoxide, the 8-hour PEL/TWA-TLV standards are
less stringent than are the outdoor standards. The rea-
son is that outdoor standards are designed to protect
the entire population, particularly infants and people
afflicted with disease or illness. Indoor standards are
designed to protect workers, who are assumed to be
9.3. Personal Clouds
Concentrations of aerosol particles and gases measured
in the vicinity of an individual who is indoors are often
greater than are concentrations measured from a station-
ary indoor monitor away from the individual. The rel-
atively high concentration of pollution measured near
an individual is called a
personal cloud
(e.g., Rodes
et al., 1991; McBride et al., 1999; Wallace, 2000). A
personal cloud may arise when a person's movement
stirs up gases and particles on clothes and nearby sur-
faces, increasing pollutant concentrations. People also
release thermal-IR radiation, which rises and thus stirs
and lifts pollutants.
Personal cloud concentrations of PM
2.5
and PM
10
were found in one study to be 1.4 and 1.6 times, respec-
tively, those of background indoor concentrations when
the person was doing normal activity, such as walking
or sitting (Ferro et al., 2004). Personal cloud concen-
trations increased to six and seventeen times, respec-
tively, those of background values when activities such
as dusting, folding clothes and blankets, and making
a bed were performed. Dusting resulted in peak PM
5
concentrations of 300
gm
−
3
for 3 minutes, whereas
two people walking resulted in peak concentrations of
130
gm
−
3
for 3 minutes. For comparison, concen-
trations with no one in the house were 11
gm
−
3
.
In sum, personal cloud concentrations are higher than
background concentrations, which are determined by
stationary monitors. Thus, personal clouds cause addi-
tional health impacts not considered when stationary
monitors are used to measure pollutant concentrations.
9.4. Regulation of Indoor Air Pollution
Worldwide, many countries regulate indoor air pollu-
tant concentrations in workplaces, public buildings, and
schools; however, few enforceable regulations exist in
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