Environmental Engineering Reference
In-Depth Information
When colorless and odorless radon
gas from such deposits seeps upward
through the soil and is released outdoors,
it disperses quickly in the atmosphere
and decays to harmless levels. However,
in buildings above such deposits, radon
gas can enter through cracks in founda-
tions and walls, openings around sump
pumps and drains, and hollow concrete
blocks (Figure 15-13). Once inside, it can
build up to high levels, especially in unven-
tilated lower levels of homes and buildings.
Radon-222 gas quickly decays into solid
particles of other radioactive elements, such
as polonium-210, that if inhaled expose lung
tissue to a large amount of ionizing radiation
from alpha particles. This exposure can dam-
age lung tissue and lead to lung cancer over
the course of a 70-year lifetime. Such exposure
makes radon the second-leading cause of lung
cancer (after smoking) in the United States.
Your chances of getting lung cancer from radon
depend mostly on how much radon is in your
home, how much time you spend in your home,
and whether you are a smoker or have ever
smoked.
According to the EPA, nearly 1 in every 15
homes in the United States has a potentially dan-
gerous level of indoor radon. Ideally, radon lev-
els should be monitored continuously in the
main living areas (not basements or crawlspaces)
for 2 months to a year. Only 6% of U.S. households had
followed the EPA's recommendation to conduct radon
tests (most lasting only 2-7 days and costing $20-100
per home).
For information about radon testing, visit the EPA
website at
http://www.epa.gov/iaq/radon
. According
to the EPA, radon control could add $350-500 to the
cost of a new home, and correcting a radon problem in
an existing house could run $800-2,500. Remedies
include sealing cracks in the foundation and walls, in-
creasing ventilation by cracking a window or installing
vents, and using a fan to create cross ventilation.
Outlet vents for furnaces and dryers
Open
window
Cracks in wall
Openings
around
pipes
Slab joints
Wood stove
Cracks in floor
Clothes
dryer
Sump
pump
Furnace
Slab
Radon-222 gas
Uranium-238
Soil
Figure 15-13
Science:
sources and paths of entry for radon-222 gas.
Have
you monitored the indoor air where you live for radon-222?
(Data from U.S.
Environmental Protection Agency)
pollution. Hairs in your nose filter out large particles.
Sticky mucus in the lining of your upper respiratory
tract captures smaller (but not the smallest) particles
and dissolves some gaseous pollutants. Sneezing and
coughing expel contaminated air and mucus when pol-
lutants irritate your respiratory system.
In addition, hundreds of thousands of tiny mucus-
coated hairlike structures called
cilia
line your upper
respiratory tract. They continually wave back and
forth and transport mucus and the pollutants they trap
to your throat (where they are swallowed or expelled).
Prolonged or acute exposure to air pollutants, in-
cluding tobacco smoke, can overload or break down
these natural defenses. This can cause or contribute
to various respiratory diseases. An example is
asthma
—
typically an allergic reaction causing sudden episodes
of muscle spasms in the bronchial walls—results in
acute shortness of breath. More than 17 million Ameri-
cans have asthma, about 5 million of them children
younger than age 5.
Years of smoking and breathing air pollutants can
lead to
lung cancer
and
chronic bronchitis,
which in-
volves persistent inflammation and damage to the
cells lining the bronchi and bronchioles. The results are
mucus buildup, painful coughing, and shortness of
15-6 HARMFUL EFFECTS
OF AIR POLLUTION
Science: How Does Your Respiratory System
Help Protect You from Air Pollution?
Your respiratory system has several ways to help
protect you from air pollution, but some air pollutants
can overcome these defenses.
Your respiratory system (Figure 15-14, p. 360) has a
number of mechanisms that help protect you from air
