large populations are exposed to diesel exhaust in everyday life , whether through their occupation or through the ambient air .
especially near highways and high traffic areas , people are exposed to traffic - related air pollutants , including diesel exhaust particles ( dep ) .
dep , produced by the combustion of diesel fuel in a compression ignition engine , is a complex mixture of gases and particulates .
the composition of the exhaust depends on a number of factors including the type of engine ( heavy or light duty ) , the type of fuel and oil , speed and load of operation , and emission control systems .
gaseous compounds present in diesel exhaust can include oxygen , carbon dioxide , nitrogen , carbon monoxide , water vapor , nitrogen oxides ( especially no ) , sulfur compounds ( especially sulfur oxides ) , volatile organic compounds ( vocs ) , low molecular weight hydrocarbons and their derivatives .
dep can contain elemental carbon , organic compounds including polyaromatic hydrocarbons ( pahs ) , metals , and other trace compounds .
approximately 92% of the particulate emitted by diesel engines is respirable ( particulate matter [ pm ] < 10 m ) , with the majority having diameters less than 1.0 micron .
dep was classified as a definite human carcinogen ( group 1 ) by the international agency for research on cancer ( iarc ) at 2012 based on recently sufficient epidemiological evidence for lung cancer .
however , we have learned from other carcinogens , such as radon , that initial studies showing a risk in heavily exposed occupational groups were followed by positive findings for the general population .
the one consistent observation that links the pulmonary and cardiovascular effects of inhaled pm is oxidative stress .
ultrafine particles ( ufps ) have emerged as a potentially important environmental health concern as they are produced in large numbers by vehicle emissions and may contribute to previously reported associations between traffic pollution and acute cardiovascular morbidity .
particular emphasis is placed on the vascular and atherosclerotic effects of urban air pollution and diesel exhaust emissions as rich sources of environmental ufps .
patients with chronic airway diseases , such as asthma and chronic obstructive pulmonary disease ( copd ) , may be more vulnerable to the deleterious effects of dep . diesel exhaust may initiate allergic reactions or increase immunological response to other allergens .
increases in hospital admission , higher incidence of respiratory symptoms , and decreases in lung function are associated with exposures to airborne particulate , including dep .
increased mortality rates are also reported , particularly in the elderly and those with cardiopulmonary conditions . in prospective mortality study , each 10 g / m elevation in fine particulate air pollution was associated with approximately a 4% , 6% , and 8% increased risk of all - cause , cardiopulmonary , and lung cancer mortality , respectively .
the three major sources of diesel exhaust are mobile sources ; stationary area sources ; and stationary point sources .
non - road sources can double the exposure to diesel exhaust in metropolitan area such as seoul .
new technology diesel engines , operating on ultra - low sulfur diesel fuel and oxidation catalysts and wall - flow particulate filters , have fundamentally different exhaust characteristics than traditional diesel engines .
euro 5 and euro 6 standards changed common european union rules on the construction of motor vehicles , and reduced the emission of atmospheric pollutants ( both particulates and nox ) from light duty vehicles .
the main effect of euro 5 is to decrease the emission of pm from diesel cars from 25 mg / km to 5 mg / km .
euro 6 limits will mainly decrease the emissions of nitrogen oxide from diesel cars further , from 180 mg / km to 80 mg / km .
recent regulations regarding fuel composition and emission standards in south korea should result in lower diesel exhaust emissions across south korea .
although the change to ultralow sulphur fuels will decrease sulphur emissions , significant decreases in dep and other diesel exhaust constituents will not be evident immediately , as older technology engines will remain in use until replacement is required .
data from pm10 emission in south korea estimated that over 53% of pm10 emitted from the transportation sector was attributable to diesel engines .
although regulation of engine performance and fuel formulation has decreased exhaust emissions , the increased numbers of vehicles and increased use of sports utility vehicles are continued issues of concern .
it is estimated that portion of diesel car in 2025 will exceed gasoline car in seoul metropolitan area .
diesel engine exhaust also contributes to the formation of smog , composed primarily of ground level ozone ( formed by the reaction of nitrous oxides and vocs , or vocs , in sunlight ) and pm .
taxi has also unique characteristics such as , slowly driving and sudden stopping . in this circumstances , diesel car with high technology , such satisfaction of euro 5 and euro 6 standards , may emit more exhaust particles , compared to other type engine car such as lpg engine . at testing by korea automotive technology institute ( katech ) ,
have 0.605 g / km nox emissions , compared to 0.012 nox emissions in lpg . total running distance by taxi is 5,174,962,493 km / yr in seoul .
if lpg taxis in seoul are all converted into diesel cars , nox emissions are estimated 50 times from 62 ton / yr to 3,131 ton / yr by emission factors investigated by katech .
pm can also be formed in the atmosphere from the reaction of various gases ; sox , nox , and nh3 .
increasing environmental concerns over the past two decades have resulted in remarkable development in diesel engine technology . due to strong interplay between standards and technology ,
new technology enables more stringent standards . for diesel engines , this required changes in the fuel such as marked decreases in sulfur content , changes in engine design to burn diesel fuel more efficiently and reductions in emissions through exhaust control technology
however , while the amount of particulates and chemicals are reduced with these changes , it is not yet clear how the quantitative and qualitative changes may translate into altered health effects ; further research to give an answer to this question is needed .
in addition , existing fuels and vehicles without these modifications will take many years to be replaced , in south korea , where regulatory measures are currently also less stringent .
especially data on the occurrence and health impact of diesel exhaust are very limited . according to organization for economic cooperation and development ( oecd ) health data , avoidable asthma hospital admission rates in population age 15 and over , at 2009 , are 101.5/ 100,000 persons , while oecd averages are 51.8/100,000 persons .
avoidable copd hospital admission rates in population age 15 and over , at 2009 , are 222/100,000 persons , while oecd averages are 198/100,000 persons .
the incidence rate for all cancers combined in south korea showed an annual increase of 3.3% from 1999 to 2009 .
korean people have high chronic disease incidences of cancer and chronic respiratory diseases , such as asthma and copd .
increases of diesel car will threaten the health of people , especially vulnerable group , in spite of recent high technology advancement . to protect people against dep ,
progressive strategies are needed , including disallowance of diesel taxi , more strict regulation of diesel engine emission , obligatory diesel particulate filter attachment in outworn diesel car , and close monitoring about health effects of dep .
 diesel exhaust particles ( dep ) contain elemental carbon , organic compounds including polyaromatic hydrocarbons ( pahs ) , metals , and other trace compounds . 
 diesel exhaust is complex mixture of thousands of chemicals . over forty air contaminants 
 are recognized as toxicants , such as carcinogens . 
 most diesel exhaust particles have aerodynamic diameters falling within a range of 0.1 to 0.25 m . 
 dep was classified as a definite human carcinogen ( group 1 ) by the international agency for research on cancer at 2012 based on recently sufficient epidemiological evidence for lung cancer . 
 significant decreases in dep and other diesel exhaust constituents will not be evident immediately , and outworn diesel car having longer mileage still threatens health of people in spite of recent remarkable development in diesel engine technology . 
 policy change in south korea , such as introduction of diesel taxi , may raise health risk of air pollution in metropolitan area with these limitations of diesel engine . to protect people against dep in south korea , 
 progressive strategies are needed , including disallowance of diesel taxi , more strict regulation of diesel engine emission , obligatory diesel particulate filter attachment in outworn diesel car , and close monitoring about health effects of dep . 
What Are Diesel Exhaust Particles?
Carcinogenicity and Other Health Effects
Environmental Exposures
Exposure Reduction in the Public Health