7
Fuels and Trends
released in the atmosphere interact with other pollutants (like photochemical reactions) and disturb the ecological balance. Faced with the growing air
pollution related problems, a number of countries have established ambient
air quality standards to protect their environment.
The main pollutants of internal combustion engines include particulate
matter, unburned hydro carbons, CO, SO 2 , and NO x . These pollutants have
serious effects on human health. Research is being carried out to produce
alternative fuels, mainly directed toward reducing these harmful pollutant
emissions. At this point, it would be appropriate to discuss the related health
effects of various diesel pollutants (Ramadhas 2005).
The principal source of nitrogen oxides—nitric oxide (NO) and nitrogen
dioxide (NO 2 ) are collectively known as NO x . Nitric oxide (NO) emissions
from engine exhaust is oxidized to nitrogen dioxides (NO 2 ), which can react
with unburned hydrocarbon emissions and other sources allowing the concentration of ozone to increase around dense traffic. The NO and NO 2 concentrations are greatest in urban areas where traffic is heaviest. Exposure
to NO 2 is linked with increased susceptibility to respiratory infection and
viral infections such as influenza, lung irritation, edema of lungs, increased
airway resistance in asthmatics, bronchitis and pneumonia, decreased pulmonary function, and increase in sensitivity to allergens. Nitrogen oxides
combine with water vapor to form nitric acid and are removed from the
atmosphere by direct deposition to the ground, or transferred to cloud or
rainwater, thereby contributing to acid deposition.
Major sources of sulfur dioxide (SO 2 ) emissions are diesel automobiles,
powerhouses, and petroleum industries. The SO 2 can impair lung function
by constricting airways and damaging lung tissue, aggravate asthma and
emphysema, and lead to suffocation and irritation to the throat. The SO 2 in
ambient air is also associated with asthma and chronic bronchitis. Sulfur
dioxide is a corrosive acid gas, which combines with water vapor in the
atmosphere to produce acid rain. It causes acidification of lakes and streams
and can damage trees, crops, historic buildings, and statues.
Concern about the potential health impacts of PM10 has increased very rapidly over recent years. Airborne particulate matter varies widely in its physical
and chemical composition, source, and particle size. The particulates in air of
a very small size ( < 10 µm) are of major current concern as compared to larger
particulates. The smaller particulates are small enough to penetrate deep into
the lungs and so potentially pose significant health risks.
There are two main groups of hydrocarbons of concern: volatile organic
compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Volatile
organic compounds are released in vehicle exhaust gases either as unburned
fuels or as combustion products, and are also emitted by the evaporation of
solvents and motor fuels. The VOCs effects include eye irritation, respiratory
irritation, and cancer. The VOC condense together with SO 2 to create particulates, including smoke, soot, and dust. Benzene content in atmosphere is the
main sources of emissions emitted in vehicle exhaust.
Fuels and Trends
released in the atmosphere interact with other pollutants (like photochemical reactions) and disturb the ecological balance. Faced with the growing air
pollution related problems, a number of countries have established ambient
air quality standards to protect their environment.
The main pollutants of internal combustion engines include particulate
matter, unburned hydro carbons, CO, SO 2 , and NO x . These pollutants have
serious effects on human health. Research is being carried out to produce
alternative fuels, mainly directed toward reducing these harmful pollutant
emissions. At this point, it would be appropriate to discuss the related health
effects of various diesel pollutants (Ramadhas 2005).
The principal source of nitrogen oxides—nitric oxide (NO) and nitrogen
dioxide (NO 2 ) are collectively known as NO x . Nitric oxide (NO) emissions
from engine exhaust is oxidized to nitrogen dioxides (NO 2 ), which can react
with unburned hydrocarbon emissions and other sources allowing the concentration of ozone to increase around dense traffic. The NO and NO 2 concentrations are greatest in urban areas where traffic is heaviest. Exposure
to NO 2 is linked with increased susceptibility to respiratory infection and
viral infections such as influenza, lung irritation, edema of lungs, increased
airway resistance in asthmatics, bronchitis and pneumonia, decreased pulmonary function, and increase in sensitivity to allergens. Nitrogen oxides
combine with water vapor to form nitric acid and are removed from the
atmosphere by direct deposition to the ground, or transferred to cloud or
rainwater, thereby contributing to acid deposition.
Major sources of sulfur dioxide (SO 2 ) emissions are diesel automobiles,
powerhouses, and petroleum industries. The SO 2 can impair lung function
by constricting airways and damaging lung tissue, aggravate asthma and
emphysema, and lead to suffocation and irritation to the throat. The SO 2 in
ambient air is also associated with asthma and chronic bronchitis. Sulfur
dioxide is a corrosive acid gas, which combines with water vapor in the
atmosphere to produce acid rain. It causes acidification of lakes and streams
and can damage trees, crops, historic buildings, and statues.
Concern about the potential health impacts of PM10 has increased very rapidly over recent years. Airborne particulate matter varies widely in its physical
and chemical composition, source, and particle size. The particulates in air of
a very small size ( < 10 µm) are of major current concern as compared to larger
particulates. The smaller particulates are small enough to penetrate deep into
the lungs and so potentially pose significant health risks.
There are two main groups of hydrocarbons of concern: volatile organic
compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Volatile
organic compounds are released in vehicle exhaust gases either as unburned
fuels or as combustion products, and are also emitted by the evaporation of
solvents and motor fuels. The VOCs effects include eye irritation, respiratory
irritation, and cancer. The VOC condense together with SO 2 to create particulates, including smoke, soot, and dust. Benzene content in atmosphere is the
main sources of emissions emitted in vehicle exhaust.