because the basis for setting standards is developed from health-based criteria. There
are six primary air pollutants that affect the design and manufacture of gasoline.
These are:
• Lead
• Carbon monoxide (CO)
• Sulfur dioxide (SO 2 )
• Nitrogen dioxide (NO 2 )
• Particulate matter
• Ozone (O 3 )
Lead. This emission from gasoline engines has been known to be toxic for several
decades. It adversely affects the kidneys, liver, and other organs and leads to
neurological impairment, learning deficits, and behavioral disorders. The reduction
of lead programs conducted in the 1970s and 1980s have made leaded gasoline
(TEL added) unavailable for on-road vehicles since the 1990s.
Carbon monoxide (CO).This is a colorless, odorless, and poisonous gas produced from the incomplete combustion of carbon in fuels. Elevated exposures are
serious for those suffering from cardiovascular disease and lead to visual impairment, loss of manual dexterity, and the ability to perform complex tasks. At high
enough levels, it depresses cardiac activity and respiration and causes convulsions
and ultimately death. Over half the carbon monoxide emissions are from motor
vehicles.
Sulfur dioxide. This is formed during burning of sulfur-containing fuels. Motor
vehicles are a minor source of SO 2 due to the desulfurizing processes used in the
production of motive fuel components. Short-term exposure to high concentrations
leads to reduced lung function, while longer exposures are associated with chronic
respiratory problems. Sulfur dioxide mixed with nitrogen oxide is a major contributor to the formation of acid rain. This in turn causes acidification of lakes, rivers,
and waterways. It damages crops and trees and accelerates the corrosion of building
materials and coatings.
Nitrogen dioxide. Also known as nitrogen peroxide, nitrogen dioxide is a brown
gas formed by high-temperature combustion of fuels. It is one of a family of
nitrogen oxides which are often treated as one species under the term NO x . Nitrogen
dioxide is a severe irritant to the lungs and can cause respiratory infections,
pneumonia, and bronchitis. Nitrogen dioxide coupled with volatile organic compounds (VOC) and ozone are the main components of smog.
Particulate matter. Dust, dirt, smoke, and liquid droplets form the particulate
matter in motor emission and pollutants. Some of the liquid droplets are formed in
the atmosphere by the condensation of sulfates, nitrates, and hydrocarbons. Fine
particles with diameter less than 2.5 μm are emitted by motor vehicles. Gasolinedriven vehicles, however, do not emit significant levels of particulate matter
compared with diesel-driven engines. Particulate matter aggravates existing respiratory and cardiovascular disease, damages lung tissue, and may cause cancer. Fine
particles of 2.5 μm or less are considered more serious since they can penetrate
72
D.S.J. Jones and S.A. Treese
are six primary air pollutants that affect the design and manufacture of gasoline.
These are:
• Lead
• Carbon monoxide (CO)
• Sulfur dioxide (SO 2 )
• Nitrogen dioxide (NO 2 )
• Particulate matter
• Ozone (O 3 )
Lead. This emission from gasoline engines has been known to be toxic for several
decades. It adversely affects the kidneys, liver, and other organs and leads to
neurological impairment, learning deficits, and behavioral disorders. The reduction
of lead programs conducted in the 1970s and 1980s have made leaded gasoline
(TEL added) unavailable for on-road vehicles since the 1990s.
Carbon monoxide (CO).This is a colorless, odorless, and poisonous gas produced from the incomplete combustion of carbon in fuels. Elevated exposures are
serious for those suffering from cardiovascular disease and lead to visual impairment, loss of manual dexterity, and the ability to perform complex tasks. At high
enough levels, it depresses cardiac activity and respiration and causes convulsions
and ultimately death. Over half the carbon monoxide emissions are from motor
vehicles.
Sulfur dioxide. This is formed during burning of sulfur-containing fuels. Motor
vehicles are a minor source of SO 2 due to the desulfurizing processes used in the
production of motive fuel components. Short-term exposure to high concentrations
leads to reduced lung function, while longer exposures are associated with chronic
respiratory problems. Sulfur dioxide mixed with nitrogen oxide is a major contributor to the formation of acid rain. This in turn causes acidification of lakes, rivers,
and waterways. It damages crops and trees and accelerates the corrosion of building
materials and coatings.
Nitrogen dioxide. Also known as nitrogen peroxide, nitrogen dioxide is a brown
gas formed by high-temperature combustion of fuels. It is one of a family of
nitrogen oxides which are often treated as one species under the term NO x . Nitrogen
dioxide is a severe irritant to the lungs and can cause respiratory infections,
pneumonia, and bronchitis. Nitrogen dioxide coupled with volatile organic compounds (VOC) and ozone are the main components of smog.
Particulate matter. Dust, dirt, smoke, and liquid droplets form the particulate
matter in motor emission and pollutants. Some of the liquid droplets are formed in
the atmosphere by the condensation of sulfates, nitrates, and hydrocarbons. Fine
particles with diameter less than 2.5 μm are emitted by motor vehicles. Gasolinedriven vehicles, however, do not emit significant levels of particulate matter
compared with diesel-driven engines. Particulate matter aggravates existing respiratory and cardiovascular disease, damages lung tissue, and may cause cancer. Fine
particles of 2.5 μm or less are considered more serious since they can penetrate
72
D.S.J. Jones and S.A. Treese