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Fuels are part of our lives. They
are used to power cars, trucks, buses, trains, garden equipment,
boats and snowmobiles, as well as pumps, compressors and generators.
We depend on fuels to move freight and perform farm, construction
and other labor. Unfortunately, their widespread use means we are
exposed to fuels and their emissions on a daily basis.
The California Environmental Protection
Agency's Office of Environmental Health Hazard Assessment (OEHHA)
assesses health risks from toxic substances, including those found
in fuels. The American Lung Association of California (ALAC) and
its 15 local associations work to prevent lung disease and promote
lung health. Since 1904, the American Lung Association has been
fighting lung disease through education, community service, advocacy
and research.
This fact sheet by OEHHA and the
American Lung Association of California (ALAC) provides health information
on our two most commonly used motor vehicle fuels, gasoline and
diesel fuel.
What harmful substances are found
in gasoline and diesel fuel?
Gasoline and diesel fuels contain
toxic substances that can enter the environment and cause adverse
health effects in people. Some of these substances, such as benzene,
toluene and xylenes, are found in crude oil and occur naturally
in fuels and their vapors. Other substances, such as 1,3-butadiene
and formaldehyde, are formed in engines during combustion and are
only present in exhaust.
Other harmful pollutants found in engine exhaust include particulate
matter (known more commonly as soot), nitrogen oxides, carbon monoxide,
sulfur dioxide and various hydrocarbons. Ozone, the major component
of urban smog, is formed when nitrogen oxides react in sunlight
with hydrocarbons.
Diesel exhaust is a particular health
concern. There are
1.25 million diesel-fueled engines and vehicles operating in California.
These diesel vehicles account for only 2 percent of on-road motor
vehicles in the state, but they produce 30 percent of the nitrogen
oxides and 60 percent of the particulate matter directly emitted
from California motor vehicles. Diesel exhaust also contains over
40 different substances identified by the California Air Resources
Board (ARB) as toxic air contaminants that may pose a threat to
human health. The particulate matter in diesel exhaust has been
identified as a toxic air contaminant by ARB, and it has been linked
to lung cancer.
How do fuels enter the environment?
The harmful substances in fuels can
enter the environment in a number of ways throughout the entire
cycle of fuel production, manufacturing, transportation, storage,
distribution and usage. Most commonly, they come out the tailpipes
of vehicles as exhaust or unburned fuel. Fuel vapors escape directly
from automobile engines and gas tanks, especially on hot days. They
can also escape into the air during refueling, or when liquid fuel
evaporates from a spill. Fuels can enter lakes and reservoirs through
accidental spills or from motorized boats and personal watercraft.
Fuels spilled on the ground or leaking from fuel storage tanks can
contaminate groundwater. Substances in airborne engine exhaust settle
directly onto water, soil and vegetation, or they can be washed
down onto these surfaces when it rains. Even groundwater can be
contaminated in these ways. Also, fuel components are released into
the environment during oil drilling, refining and transportation.
How are people exposed to fuels?
Just breathing the air exposes people
to fuel components, especially in urban areas. People are exposed
to gasoline and diesel exhaust when they drive or ride in a vehicle,
jog or bike along roads or park in a public garage. Motorists are
further exposed to gasoline vapors when they fill up their vehicle's
fuel tank. People who work in or live near freeways, refineries,
chemical plants, loading and storage facilities or other places
that handle crude oil and petroleum products may be exposed to higher
levels of fuel components than the general public and face higher
health risks.
What health effects are associated
with exposure to fuels?
Breathing gasoline and diesel vapors
can irritate the nose and throat and cause headaches, dizziness,
nausea, vomiting and confusion. Of course, most people are not exposed
to high enough levels of fuels to become ill in this manner. However,
we are all exposed to lower levels of fuel components throughout
our lives. This lifelong exposure can increase the risk of adverse
health effects.
Both liquid gasoline and motor vehicle
exhaust contain chemicals that can cause cancer. Benzene, a fundamental
component of gasoline and diesel fuel as well as vehicle exhaust,
causes cancer in humans. Gasoline exhaust also contains cancer-causing
1,3-butadiene, formaldehyde and acetaldehyde. Diesel exhaust contains
several dozen toxic substances and scientific studies have shown
that workers exposed to diesel exhaust are more likely to develop
lung cancer. Long-term exposure to particles in diesel exhaust poses
the highest cancer risk of any toxic air contaminant evaluated by
OEHHA. ARB estimates that about 70 percent of the cancer risk that
the average Californian faces from breathing toxic air pollutants
stems from diesel exhaust particles. The microscopic particles making
up diesel exhaust particulate matter are less than one-fifth the
thickness of a human hair. They are small enough to penetrate deep
into the lungs, where they can contribute to respiratory disease.
Gasoline and diesel exhausts contain
nitrogen oxides, carbon monoxide and sulfur dioxide. Nitrogen oxides
can damage lung tissue, lower the body's resistance to respiratory
infection and worsen chronic lung diseases such as asthma. As mentioned
earlier, nitrogen oxides react in the atmosphere with hydrocarbons
to form ozone, the major component of urban smog. Ozone is a strong
irritant to the eyes and respiratory tract. It can make respiratory
problems worse for people who already have asthma and other respiratory
diseases. Children, senior citizens and people with chronic lung
disease, such as Chronic Obstructive Pulmonary Disease (COPD), are
especially sensitive to ozone. Ozone also hurts the lungs of healthy
people who exercise outdoors when ozone levels are high.
Carbon monoxide is a colorless, odorless
gas that limits the blood's ability to transport oxygen to body
tissues. Its presence in the body places a strain on people who
already have cardiac or respiratory diseases, as well as pregnant
women and the elderly.
MTBE
Another concern about gasoline is
methyl tertiary butyl ether, or MTBE, which originally was used
in gasoline in small amounts to reduce engine knocking. Beginning
in the mid-1990s, more MTBE was added to make gasoline burn cleaner
and produce less air pollution. MTBE is present in gasoline vapors
and in the exhaust.
Regulatory agencies for years have
required the monitoring of drinking-water wells for benzene and
other gasoline components that can enter groundwater from leaking
underground tanks. As its use became more widespread in the 1990s,
MTBE also began to show up in California drinking water wells that
were near leaking underground tanks. Bacteria do not break MTBE
down as readily as they do benzene, so MTBE will stay in the water
longer. MTBE is also more difficult and expensive to remove than
benzene. Even at very low concentrations, MTBE has an unpleasant
taste and odor that renders drinking water unusable.
Although not as toxic as benzene,
MTBE has been shown to cause cancer in certain laboratory animals
and may cause cancer in humans. Because of concerns about MTBE in
California's drinking water supplies and its general impact on public
health and the environment, Governor Gray Davis ordered the removal
of MTBE from California's gasoline by the end of 2002.
Concerns about MTBE also prompted
legislation that requires the study of potential health impacts
prior to the adoption of any new state gasoline regulations that
are intended to improve air quality. OEHHA is developing methods
to study the risks that could occur throughout the entire "life
cycle" of a fuel, from its production, storage, transportation,
dispensing and use, through its recycling and disposal.
What has been done to reduce the
public's risk from exposure to fuels?
Over the past two decades, many significant
improvements have made both fuels and engines cleaner and far less
polluting. Highly toxic lead was removed from gasoline. ARB has
established stricter emission standards for gasoline- and diesel-fueled
cars, trucks and buses. During the 1990s, ARB required the reformulation
of gasoline and diesel fuel to reduce smog-forming and toxic emissions.
Health assessments developed by OEHHA have guided ARB in its decisions.
Thanks to these changes, pollution levels in many areas of California
have decreased substantially in recent years. New vehicle emission
standards, which will be phased in during the next several years,
are intended to further reduce unhealthy levels of air pollution.
However, dramatically rising vehicle usage in California presents
a continual challenge to regulatory control efforts and threatens
to erode the air quality gains that have been made.
Recent emission standards have reached
beyond "traditional" motor vehicles to include motorcycles;
outboard boat engines; lawn and garden equipment; and farm, construction
and utility equipment. These new requirements will help to reduce
harmful emissions from these formerly unregulated engines, which
can produce many times the pollution of a late-model automobile.
To protect water supplies from leaking
underground fuel storage tanks, federal and state regulations require
that old, single-walled tanks be replaced with new, double-lined
tanks with leak detectors. The State Water Resources Control Board
and nine regional water quality control boards oversee these regulations.
In addition, ARB standards for new outboard engines and personal
watercraft intended to reduce emissions will reduce fuel releases
into water. There are even requirements for new portable gas cans
that will help reduce accidental spills.
What more must be done to protect
public health?
Despite all of the progress made
so far, more than 90 percent of Californians still breathe unhealthy
air. The reason is mostly due to motor vehicles. The number of vehicles
on the road and the miles they travel continue to grow. Even as
older vehicles are replaced with newer, less polluting ones, our
progress towards clean air is being eroded by growth in vehicle
travel.
California is continuing to take
the lead in developing cleaner fuels and setting stricter emission
standards for gasoline and diesel-fueled vehicles and other engines.
These programs will help to reduce people's exposure to fuel toxics
and smog.
State law requires measures to reduce
the public's risk from exposure to toxic air contaminants, including
diesel exhaust. ARB has approved a plan to reduce particle emissions
from diesel engines by 85 percent by 2020 through measures such
as low-sulfur diesel fuel, equipping diesel engines with particulate
traps and the use of alternative fuels.
Alternative fuels include electricity,
natural gas, fuel cells, ethanol, methanol and propane. All of them
have the potential to produce less air pollution than gasoline or
diesel fuel. Toxic and smog-forming emissions from electricity,
natural gas and other alternative fuel vehicles can be dramatically
lower than emissions from conventional vehicles. As a result of
ARB regulations, major vehicle manufacturers will be producing increasing
numbers of vehicles that run on alternative fuels.
What can I do to help?
Anything you do to reduce the amount
of fuel you use will help protect the environment. Bicycle or walk
instead of driving. Try riding public transit, carpooling or vanpooling
instead of driving alone. Take advantage of any "telework"
(work at home) programs your employer may have. If you drive, keep
your vehicle well tuned. A properly maintained vehicle contributes
less to air pollution and saves you money on gas. Run all your errands
at once because a warm engine pollutes less. When refueling your
vehicle, don't top off at the gas pump. If the dispensing nozzle
is equipped with a hold-open latch, use it and move upwind of the
fumes. Close your vehicle's windows to protect any passengers.
When shopping for your next car,
look for the most efficient, lowest polluting model or even a zero-polluting
electric car. ARB's Web site has a "Clean Car Buyers Guide"
with information on low-polluting vehicles. If you must drive on
days with unhealthy air, drive your newest car. Newer cars generally
pollute less than older models.
When using motorized watercraft, prevent leaks and spills of fuel
and oil by properly maintaining the engines, lines and hoses. Don't
let the tank overflow and use an oil-only absorbent to clean up
any drips. When buying a new outboard engine or personal watercraft,
look for engine labels certifying that the equipment meets California's
low-emission standards.
Use electric lawn and garden equipment
when possible. Reduce, re-use and recycle as much as possible. It
takes fuel to produce and ship new goods.
For more information on how you can
reduce air pollution, contact the American Lung Association at the
phone numbers or Web site address listed below.
For further information
Office of Environmental Health Hazard Assessment
1001 I Street, P.O. Box 4010, Sacramento,
CA 95812-4010
(916) 324-7572 www.oehha.ca.gov
Air Resources Board
1001 I Street, Sacramento, CA 95814
(800) 363-7664
www.arb.ca.gov
American Lung Association of California
921 11th Street, Suite 700, Sacramento, CA
95814
(916) 442-4446
For your local office, call (800) LUNG-USA
www.californialung.org
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