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Ozone: What is Ozone? |
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What is Ozone?
Ozone is a molecule
composed of three atoms of oxygen. Two atoms of
oxygen form the basic oxygen molecule--the oxygen
we breathe that is essential to life. The third
oxygen atom can detach from the ozone molecule,
and re-attach to molecules of other substances,
thereby altering their chemical composition. It
is this ability to react with other substances
that forms the basis of manufacturers’ claims
How is Ozone Harmful?
The same chemical
properties that allow high concentrations of ozone
to react with organic material outside the body
give it the ability to react with similar organic
material that makes up the body, and potentially
cause harmful health consequences. When
inhaled, ozone can damage the lungs (see - "Ozone
and Your Health" - www.epa.gov/airnow/brochure.html).
Relatively low amounts can cause chest pain, coughing,
shortness of breath, and, throat irritation. Ozone
may also worsen chronic respiratory diseases such
as asthma and compromise the ability of the body
to fight respiratory infections.
People vary widely in their susceptibility to
ozone. Healthy people, as well as those with respiratory
difficulty, can experience breathing problems
when exposed to ozone. Exercise during exposure
to ozone causes a greater amount of ozone to be
inhaled, and increases the risk of harmful respiratory
effects. Recovery from the harmful effects can
occur following short-term exposure to low levels
of ozone, but health effects may become more damaging
and recovery less certain at higher levels or
from longer exposures (US EPA, 1996a,
Is There Such a Thing as "Good Ozone"
and "Bad Ozone"?
The phrase "good
up high - bad nearby" has been used by
the U.S. Environmental Protection Agency (EPA)
to make the distinction between ozone in the upper
and lower atmosphere. Ozone in the upper atmosphere--referred
to as "stratospheric ozone"--helps filter
out damaging ultraviolet radiation from the sun.
Though ozone in the stratosphere is protective,
ozone in the atmosphere - which is the air we
breathe - can be harmful to the respiratory system.
Harmful levels of ozone can be produced by the
interaction of sunlight with certain chemicals
emitted to the environment (e.g., automobile emissions
and chemical emissions of industrial plants).
These harmful concentrations of ozone in the atmosphere
are often accompanied by high concentrations of
other pollutants, including nitrogen dioxide,
fine particles, and hydrocarbons. Whether
pure or mixed with other chemicals, ozone can
be harmful to health.
| Ozone
Heath Effects and Standards |
| Health Effects |
Risk Factors |
Health Standards* |
Potential
risk of experiencing:
Decreases in lung function
Aggravation of asthma
Throat irritation and cough
Chest pain and shortness of breath
Inflammation of lung tissue
Higher susceptibility to respiratory
infection |
Factors
expected to increase risk and severity
of health effects are:
Increase in ozone air concentration
Greater duration of exposure for some
health effects
Activities that raise the breathing
rate (e.g., exercise)
Certain pre-existing lung diseases
(e.g., asthma) |
The
Food and Drug Administration (FDA)
requires ozone output of indoor medical
devices to be no more than 0.05 ppm.
The Occupational Safety and Health
Administration (OSHA) requires that
workers not be exposed to an average
concentration of more than 0.10 ppm
for 8 hours.
The National Institute of Occupational
Safety and Health (NIOSH) recommends
an upper limit of 0.10 ppm, not to
be exceeded at any time.
EPA’s National Ambient Air Quality
Standard for ozone is a maximum 8
hour average outdoor concentration
of 0.08 ppm (see - the Clean Air Act
- www.epa.gov/air/caa/title1.html#ib) |
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Click
here for more information on the Good and Bad
of Ozone |
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