Carbon
Monoxide | Hydrocarbons
Nitrogen Oxides | Particulate
Matter
Hydrocarbons
are a precursor to ground-level ozone,
a serious air pollutant
in cities across the United States. A key component of smog,
ground-level ozone is formed by reactions involving hydrocarbons
and nitrogen oxides in
the presence of sunlight. Hydrocarbon emissions
result from incomplete fuel combustion
and from fuel evaporation.
Today's cars are equipped with emission controls designed to reduce
both exhaust and evaporative hydrocarbon emissions.
1999 National Emissions
by Source:
Hydrocarbons
Ground-level ozone causes health problems such as difficulty breathing,
lung damage, and reduced cardiovascular functioning. A number of
hydrocarbons are also considered toxic,
meaning they can cause cancer or other health problems.
Learn more about the role hydrocarbons play in creating ozone,
the health and environmental effects
of ozone, and about hydrocarbon
levels where you live.
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