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Air Pollution and Health Risk
How Do We Learn About Risks?
The warnings about risks from hazardous
substances are everywhere. Every day, the news media report information on
hazardous substances. Many products now tout warning labels or claims about
being "all natural" and "chemical free." How do we know
when a risk is serious? How do researchers estimate risk, and how does the
government use this information to develop regulations that limit our exposure
to hazardous substances? The following information should help you to answer
these questions.
Which Risks Are of Greatest Concern?
How Do Researchers Estimate
Risk?
| Health
Risk = Hazard x Exposure |
| Health
risk is the probability, or chance, that exposure to a hazardous substance
will make you sick.
|
Animal
experiments or human studies provide information about how hazardous a
substance is. Scientists use the results of such studies to estimate the
likelihood of illness at different levels of exposure. |
Information
on exposure comes from two places: (1) monitors placed on factory
smokestacks or at special places in your community, or (2) from
mathematical models that estimate exposure based on amounts of chemicals
released. |
Why Is Information Used for
Health Risk Decision Making Uncertain?
Uncertainty About Hazard
Many hazards are identified by testing animals. We do not know for certain
whether the hazard estimated using animal studies is the same for humans.
Information is uncertain because of:
- Lack of complete scientific
understanding of how a hazardous substance makes you sick and how it moves
through the air, water, or ground;
- too few human or animal studies of
the health effects of individual chemicals and mixtures of chemicals;
- the variable nature of weather
patterns affecting exposure;
- the inability to know everything
Uncertainty About
Exposure
We do not know for certain that monitors or mathematical models always
produce accurate estimates of exposure. It is nearly impossible to account for
the different exposures a person may encounter daily.
What Are Important Factors
in Risk Decision Making?
Balancing Scientific
Results with Public and Economic Concerns
Ideally, regulators would like to eliminate all pollution and its risks, but
this is usually not a realistic expectation. Regulators must address the most
important risks and decrease them to the level at which they believe the risks
are smaller than the benefits of the activity causing the pollution.
This is similar to what millions do each
day when they balance the risks of an automobile accident with the convenience
and necessity of driving. Just as a driver will buckle up and drive
defensively to be safer, agencies take regulatory action to eliminate as much
risk as is possible without losing the benefit.
Public Risk Perceptions
Scientific results may show that certain hazardous substances pose a low
health risk to people, but the public may still be concerned about these
hazardous substances because of different attributes of the risk. Other
attributes may affect people's perceptions of a risk:
- How serious and dreaded is the
illness?
- How certain is scientific knowledge?
- What is the catastrophic potential?
- Who bears the risk?
- Is the risk voluntary?
- Who receives the benefits of the
"risky" activity?
Putting Risks in Perspective
What Do the Numbers
Mean?
To provide an idea of the size of risks from environmental hazards as risk
analysts will describe them to you, the continuum above presents risk
statistics for some familiar events. Risk analysts describe risks numerically
in scientific notation, for example 1 x 10[-5], which means that there is one
chance in 100,000 of an event occurring. It is important to note that these
risk statistics are population averages, while risk analysts usually estimate
risk to the maximum exposed individual.
Actions to Reduce Risk
By becoming better informed you can reduce the risks that you determine to be
unacceptable. This may mean changing your lifestyle or providing input to
government, industry, and consumer / environmental interest groups. If you
would like more information the sources listed below are a good place to
start. You may also want to contact your local health department or regional
or state environmental agencies for other information sources.
U.S. Environmental Protection Agency
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