Environmental Engineering Reference
In-Depth Information
The greatest risks many people face today are
rarely dramatic enough to make the daily news. In
terms of the number of premature deaths per year (Fig-
ure 14-12) and reduced life span (Figure 14-13, p. 342),
the greatest risk by far is poverty.
Its high death toll is a
result of malnutrition, increased susceptibility to nor-
mally nonfatal infectious diseases, and often-fatal infec-
tious diseases from lack of access to a safe water supply.
A sharp reduction in or elimination of poverty would do
far more to improve longevity and human health than any
other measure.
It would also greatly improve human
rights, provide more people with income to stimulate
economic development, and reduce environmental
degradation and the threat of terrorism. Sharply re-
ducing poverty is a win-win situation for people,
economies, and the environment.
After the health risks associated with poverty and
gender, the greatest risks of premature death mostly re-
sult from voluntary choices people make about their
lifestyles (Figures 14-12 and 14-13). The best ways to re-
duce one's risk of premature death and serious health
risks are to avoid smoking and exposure to smoke, lose
excess weight, reduce consumption of foods contain-
ing cholesterol and saturated fats, eat a variety of fruits
and vegetables, exercise regularly, not drink alcohol or
drink no more than two drinks in a single day, avoid
excess sunlight (which ages skin and causes skin can-
cer), and practice safe sex (including abstinence).
Science: Estimating Risks
from Technologies
Estimating risks from using certain technologies is
difficult because of the unpredictability of human
behavior, chance, and sabotage.
The more complex a technological system and the more
people needed to design and run it, the more difficult it
is to estimate the risks. The overall
reliability
or the
probability (expressed as a percentage) that a person or
device will perform without failure or error is the prod-
uct of two factors:
Technology
Human
System reliability (%)
reliability
reliability
With careful design, quality control, maintenance,
and monitoring, a highly complex system such as a nu-
clear power plant or space shuttle can achieve a high
degree of technological reliability. But human reliabil-
ity usually is much lower than technological reliability
and almost impossible to predict: To err is human.
Suppose the technological reliability of a nuclear
power plant is 95% (0.95) and human reliability is 75%
(0.75). Then the overall system reliability is 71% (0.95
0.75
71%). Even if we could make the technology
100% reliable (1.0), the overall system reliability would
still be only 75% (1.0
75%). The crucial
dependence of even the most carefully designed sys-
tems on unpredictable human reliability helps explain
0.75
100
Cause of death
Annual deaths
Poverty/malnutrition/
disease cycle
11 million
(75)
5 million
(34)
Tobacco
3.2 million
(22)
Pneumonia and flu
3 million
(21)
Air pollution
3 million
(21)
HIV/AIDS
3 million
(21)
Malaria
1.9 million
(13)
Diarrhea
1.7 million
(12)
Tuberculosis
1.2 million
(8)
Automobile accidents
Work-related
injury and disease
1.1 million
(8)
1 million
(7)
Hepatitis B
800,000
(5)
Measles
Figure 14-12
Global outlook:
number of deaths per year in the world from various causes. Numbers in
parentheses give these deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing
every day of the year
with no survivors. Because of sensational media coverage, most people have a distorted
view of the largest annual causes of death.
Critical thinking: which three of these items are most likely to
shorten your life span?
