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health. A review by Pope (2000) concluded that short-
term (acute) increases of 10
gm 3 PM 10 were associ-
ated with a 0.5 to 1.5 percent increase in daily mortality,
higher hospitalization and health care visits for respi-
ratory and cardiovascular disease, and enhanced out-
breaks of asthma and coughing. Increased death rates
usually occurred within 1 to 5 days following an air
pollution episode. Long-term exposures to 5
gm 3
of particles smaller than 2.5
mindiameter (PM 2.5 )
above background levels resulted in a variety of car-
diopulmonary problems, including increased mortality,
increased disease, and decreased lung function in adults
and children (Pope and Dockery, 1999). Pope et al.
(2002) found a mean increased risk of mortality due
to long-term exposure to PM 2.5 of 4 percent per 10
g
m 3 ,or0.004 per
gm 3 .
Small particles (PM 2.5 )result in more respiratory
illness and premature death than do larger aerosol par-
ticles ( Ozkatnak and Thurston, 1987; U.S. EPA, 1996).
One six-city, 16-year study concluded that people liv-
ing in areas where aerosol particle concentrations were
lower than even the U.S. federal PM 10 standard had a
lifespan 2 years shorter than people living in cleaner
air (Dockery et al., 1993). Air pollution was correlated
with death from lung cancer and cardiopulmonary dis-
ease. Fine particles, including sulfates, were correlated
with mortality. A more recent study found that each 10
Figure 5.18. Lungs of a nonsmoking teenager living in
Los Angeles who died accidentally in the 1970s.
South Coast Air Quality Management District,
www.aqmd.gov.
gm 3 of PM 2.5 reduces life expectancy by 5 to 10
months (Pope et al., 2009).
Areview of health studies concluded that ambient
PM 2.5 increases premature mortality, hospital admis-
sions, and emergency room visits for cardiovascular
and respiratory disease and development of chronic
respiratory disease (U.S. EPA, 2009b). Although some
individual chemicals in PM 2.5 are likely to be respon-
sible for most of the health damage, isolating health
effects of such chemicals has been difficult to date.
Some studies, however, discovered a link between
short-term exposure of black carbon, for example, and
cardiovascular effects (e.g., U.S. EPA, 2009b; Mordu-
khovich et al., 2009).
Figure 5.18 illustrates the health damage to the lungs
of a teenage nonsmoker resulting from severe air pollu-
tion, primarily particulate matter, in Los Angeles in the
1970s. Air pollution levels at the time were equivalent
to smoking two packs of cigarettes per day. Although air
pollution levels in the United States and much of Europe
have improved significantly since then, pollution levels
in most developing countries of the world are similar to
those found in Los Angeles in the 1970s (Chapter 8).
Living in some places, such as Linfen, China, in 2010,
was equivalent to smoking three packs of cigarettes
per day.
5.7. Quantifying the Health Effects
of Particles or Gases
Health effect rates ( y )(e.g., deaths/yr, cancers/yr, hos-
pitalizations/yr) due to a particle or gas pollutant can be
quantified with
y
=
y 0 P (1
exp [
− ×
max ( x
x th ,
0)])
(5.13)
where x is the average concentration or mixing ratio
of the pollutant, x th is the threshold concentration or
mixing ratio below which no health effect occurs,
is the fractional increase in risk of the health effect
per unit x , y 0 is the baseline health effect rate per unit
population, and P is the population. For example, in the
United States, the all-cause death rate is approximately
y 0 =
833 per 100,000 population per year. For ozone, the
threshold mixing ratio above which short-term health
effects occur is x th
=
35 ppbv, and for PM 2.5 ,itis
g/m 3 .Acompilation of studies suggests that the
0
 
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