heavy duty diesel pollu

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Heavy Duty DieselVehicle Pollution

Control: What Drives theRegulators

Michael P. WalshInternational Consultant

1. INTRODUCTIONOver the past decade, diesel technology hasadvanced tremendously. As a result, dieselcars are faster, more efficient, drive better and are quieter than ever before. Notsurprisingly, therefore, diesel sales continueto grow especially in Europe. Last year,approximately two out of five new cars soldin Europe were powered by a diesel engineand all new heavy-duty trucks were dieselfueled. Principal reasons for the success of the diesel are its superior fuel efficiency anddurability.

However, at the same time that market

forces are stimulating increased dieselsales, regulatory officials around the worldare giving greater scrutiny to these dieselvehicles and their fuels. Why? What are theforces that are driving the regulators? Thispaper will attempt to answer this question. Itwill review and summarize the health andenvironmental effects related to dieselvehicle emissions and the governmentresponses to these effects.

2. HEALTH AND

ENVIRONMENTAL CONCERNSABOUT DIESEL PM EMISSIONSEach year, more and more studies continueto point to particulate in general and dieselparticulate specifically as the cause of thousands of premature deaths. In Japan,even the courts have weighed in, awarding

damages to asthma sufferers because of thediesel vehicles emissions in the vicinity of their homes. 1 In addition, ozone (or photochemical smog as it is commonlyknown) remains a widespread problem. For example, as illustrated below, over 100million Americans still live in areas thatexceed one or more air quality standards.By far the largest numbers are subjected tohigh levels of ozone (especially 8 hour average levels above standards) and PM 2.5 .

Similarly in Japan, total suspendedparticulate levels have not improved

significantly in approximately twenty years.

1. Govt to cough up over air pollution,Mainichi Shimbun, February 1, 2000


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In Europe, while noting the significantprogress which has occurred to date and theanticipated additional emissions reductionswhich should result from the tighter standards for cars, trucks and fuels whichhave already been adopted and will bephased in over the next several years, theEuropean Commission has identified the keyremaining challenges to be:

Particulate Matter

Localized NO2 Exceedences

Ozone (compliance with NOx andVOC emissions ceilings), and

Current or emerging problemsassociated with non-regulatedpollutants such as PAH.

While many sources contribute to theseproblems, diesel trucks are increasinglybecoming the major mobile source of bothNOx and PM as light duty vehicles areincreasingly controlled. For example, asillustrated below, while only 17% of thevehicles in Japan are diesel trucks, they

contribute almost half the NOx and morethan 60% of the PM.

A. NEW US PARTICULATE STUDIESAt its annual conference in Atlanta, Georgiain 2000, the Health Effects Institute (HEI)

released the results of two major studiesfocused on fine particle health effects. Thefirst report is a re-analysis of two long-termcommunity health studies: the Harvard SixCities Study (1993), and the AmericanCancer Society Study (1995). The second,called the National Morbidity, Mortality, andAir Pollution Study (NMMAPS), is originalresearch on hospitalization and deathsassociated with air pollution in major U.S.cities.

i. The Particle Epidemiology Reanalysis Project

The Harvard Six City Study and theAmerican Cancer Society study examinedthe long-term effects of exposure toparticulate air pollution on mortality. In theHarvard Six-Cities Study, researchersfollowed the health of more than 8,000people in six small cities that fell along agradient of air pollution concentrations for aperiod of 14 to 16 years. As particleconcentrations increased, there was analmost directly proportional increase in thedeath rate in the residents studied.Residents of the most polluted city in thestudy, Steubenville, Ohio, had a 26 percentincreased risk of premature mortality,compared to the residents of the cleanestcity studied, Portage, Wisconsin. Accordingto study authors, this translates into ashortened life expectancy of one to twoyears for residents of Steubenville comparedto residents of Portage.

The March 1995 American Cancer Societystudy found an association between chronicexposure to fine particle air pollution andpremature death in a study group of over

half a million people in 151 cities. Sulfatepollution was also associated with earlydeath. The study reported strongassociations between sulfates and fineparticles and death by cardiopulmonarycauses.


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Dr. Daniel Krewski of the University of Ottawa and his associates conducted thenewly released reanalysis of these twostudies for the Health Effects Institute. First,they undertook a reanalysis of the originalstudies and a quality audit of the underlyingdata. Then they performed an extensivesensitivity analysis using alternativestatistical methods, and considering the roleof 20 potential confounders such as other pollutants, climate, and socio-economicfactors on study results. The reanalysisvalidated the original studies.

ii. The National Morbidity,Mortality and Air Pollution Study

(NMMAPS)The Health Effects Institute alsocommissioned an original nationwide studyof the short-term effects of air pollution onhuman health in the 90 largest Americancities. NMMAPS found strong evidencelinking daily increases in particulate pollutionto increases in death. The associationbetween particulate matter and mortalitypersisted even when other pollutants wereincluded in the analysis.

In addition, NMMAPS found stable androbust associations between particulatepollution and increased hospital admissionsfor cardiovascular disease, pneumonia, andchronic obstructive pulmonary disease. Asnoted in a subsequent publication, the studyfound consistent evidence that the level of PM 10 is associated with the rate of deathfrom all causes and from cardiovascular andrespiratory illnesses. The estimated increasein the relative rate of death from all causeswas 0.51 percent (95 percent posterior level,

0.07 to 0.93 percent) for each increase inthe PM 10 level of 10 g per cubic meter. 2

2. Fine Particulate Air Pollution andMortality in 20 U.S. Cities, 1987-1994",Samet, Dominici, Curriero, Coursac and

iii. Update of ACS Study Long-term exposure to levels of air pollutioncommon in many US metropolitan areasincreases the risk of death from lung cancer and other heart-lung diseases, according toanother study published in the Journal of theAmerican Medical Association. 3

The analysis is based on data collected bythe American Cancer Society (ACS) as partof the Cancer Prevention Study II (CPS-II),an ongoing prospective mortality study of approximately 1.2 million adults. ACSvolunteers enrolled individual participants inthe fall of 1982. Participants resided in all 50states, the District of Columbia, and PuertoRico, and was restricted to persons whowere aged 30 years or older and who weremembers of households with at least 1individual aged 45 years or older.Participants completed a confidentialquestionnaire, which included questionsabout age, sex, weight, height, smokinghistory, alcohol use, occupationalexposures, diet, education, marital status,and other characteristics.

This study demonstrated associationsbetween ambient fine particulate air pollutionand elevated risks of both cardiopulmonaryand lung cancer mortality. Each 10-g/m 3 elevation in long-term average PM 2.5 ambient concentrations was associatedwith approximately a 4%, 6%, and 8%increased risk of all-cause,

Zegar, The New England Journal of Medicine, December 14, 2000.

3. Lung Cancer, CardiopulmonaryMortality, and Long-term Exposure to

Fine Particulate Air Pollution, C. ArdenPope III, PhD; Richard T. Burnett, PhD;Michael J. Thun, MD; Eugenia E. Calle,PhD; Daniel Krewski, PhD; Kazuhiko Ito,PhD; George D. Thurston, ScD, Journalof the Amercian Medical Association,Vol. 287 No. 9, March 6, 2002


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cardiopulmonary, and lung cancer mortality, respectively, although themagnitude of the effect somewhat dependedon the time frame of pollution monitoring. Inaddition, this analysis addresses many of the important questions concerning theearlier, more limited analysis of the largeCPS-II cohort, including the following issues.

First, does the apparent associationbetween pollution and mortalitypersist with longer follow-up and asthe cohort ages and dies? Thepresent analysis more than doubled thefollow-up time to more than 16 years,resulting in approximately triple the

number of deaths, yet the associationsbetween pollution and mortalitypersisted.

Second, can the associationbetween fine particulate air pollutionand increased cardiopulmonary andlung cancer mortality be due toinadequate control of importantindividual risk factors? After aggressively controlling for smoking, theestimated fine particulate pollution effecton mortality was remarkably robust.

When the analysis was stratified bysmoking status, the estimated pollutioneffect on both cardiopulmonary and lungcancer mortality was strongest for never smokers vs. former or current smokers.This analysis also controlled for education, marital status, BMI, andalcohol consumption. This analysisused improved variables to control for occupational exposures andincorporated diet variables thataccounted for total fat consumption, as

well as for consumption of vegetables,citrus, and high-fiber grains. Themortality associations with fineparticulate air pollution were largelyunaffected by the inclusion of theseindividual risk factors in the models. Thedata on smoking and other individual

risk factors, however, were obtaineddirectly by questionnaire at time of enrollment and do not reflect changesthat may have occurred followingenrollment. The lack of risk factor follow-up data results in somemisclassification of exposure, reducesthe precision of control for risk factors,and constrains the ability to differentiatetime dependency.

Third, are the associations betweenfine particulate air pollution andmortality due to regional or other spatial differences that are notadequately controlled for in theanalysis? In this analysis, significant

spatial autocorrelation was notobserved after controlling for fineparticulate air pollution and the variousindividual risk factors. Furthermore,even after accounting for randomeffects across metropolitan areas andaggressively modeling a spatialstructure that accounts for regionaldifferences, the association betweenfine particulate air pollution andcardiopulmonary and lung cancer mortality persists.

Fourth, is mortality associatedprimarily with fine particulate air pollution or is mortality alsoassociated with other measures of particulate air pollution, such asPM 10 , total suspended particles, or with various gaseous pollutants? Elevated mortality risks were associatedprimarily with measures of fineparticulate and sulfur oxide pollution.Coarse particles and gaseouspollutants, except for sulfur dioxide,

were generally not significantlyassociated with elevated mortality risk.

Fifth, what is the shape of theconcentration-response function? Within the range of pollution observed inthis analysis, the concentration-response function appears to be


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monotonic and nearly linear. However,this does not preclude a leveling off (or even steepening) at much higher levelsof air pollution.

Sixth, how large is the estimatedmortality effect of exposure to fineparticulate air pollution relative toother risk factors? A detaileddescription and interpretation of themany individual risk factors that arecontrolled for in the analysis goes wellbeyond the scope of this report.However, the mortality risk associatedwith cigarette smoking has been welldocumented. The risk imposed byexposure to fine particulate air pollution

is obviously much smaller than the riskof cigarette smoking. Another risk factor that has been well documented is bodymass as measured by BMI. Mortalityrisks associated with fine particulate air pollution at levels found in more pollutedUS metropolitan areas are less thanthose associated with substantialobesity (grade 3 overweight), butcomparable with the estimated effect of being moderately overweight (grade 1to 2).

In conclusion, the findings of this studyprovide the strongest evidence to date thatlong-term exposure to fine particulate air pollution common to many US metropolitanareas is an important risk factor for cardiopulmonary mortality. In addition, thelarge cohort and extended follow-up haveprovided an unprecedented opportunity toevaluate associations between air pollutionand lung cancer mortality. Elevated fineparticulate air pollution exposures were

associated with significant increases in lungcancer mortality. Although potential effectsof other unaccounted for factors cannot beexcluded with certainty, the associationsbetween fine particulate air pollution andlung cancer mortality, as well ascardiopulmonary mortality, are observed

even after controlling for cigarettesmoking, BMI, diet, occupationalexposure, other individual risk factors,and after controlling for regional andother spatial differences .

B. EUROPEAN PM STUDYAnother study published in the British

journal, Lancet, concludes that air pollutionkills more than 40,000 people a year inAustria, France and Switzerland andcontributes to 25,000 new cases of asthmaand half a million asthma attacks 4.

Epidemiology-based exposure responsefunctions for a 10-g/m 3 increase inparticulate matter (PM 10 ) were used toquantify the effects of air pollution. Casesattributable to air pollution were estimatedfor mortality (adults=>30 years), respiratoryand cardiovascular hospital admissions (allages), incidence of chronic bronchitis (adults=>25 years), bronchitis episodes in children(20 years), and asthma attacks in adultsand children. Population exposure (PM 10 )was modeled for each km 2. The traffic-related fraction was estimated based onPM 10 emission inventories.

About half of all mortality caused by air pollution was attributed to motorized traffic,accounting also for: more than 25,000 newcases of chronic bronchitis (adults); morethan 290,000 episodes of bronchitis(children); more than 0.5 million asthmaattacks; and more than 16 million person-days of restricted activities.

The researchers calculated that the healthcosts of pollution from traffic across the

4. Public-health impact of outdoor andtraffic-related air pollution: a Europeanassessment, Lancet 2000; 356: 795 -801


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three countries amounted to about 1.7percent of the gross domestic product.

C. DIESEL TOXICITY

The concern for the carcinogenic healthhazard resulting from diesel exhaustexposures has existed for several years andis increasingly widespread. Several nationaland international agencies have designateddiesel exhaust or diesel particulate matter asa potential or probable humancarcinogen. 5,6 The International Agency for Research on Cancer (IARC) in the late1980s concluded that diesel exhaust is aprobable human carcinogen. 7 Based onIARC findings, the State of Californiaidentified diesel exhaust in 1990 as achemical known to the State to causecancer and after an extensive review in1998 listed diesel exhaust as a toxic air contaminant. 8 The National Institutes for

5. National Institute for Occupational Safetyand Health (1988) Carcinogenic effectsof exposure to diesel exhaust. NIOSHCurrent Intelligence Bulletin 50. DHHS(NIOSH) Publication No. 88-116.Centers for Disease Control, Atlanta,GA.

6. World Health Organization (1996) Dieselfuel and exhaust emissions: Internationalprogram on chemical safety. WorldHealth Organization, Geneva,Switzerland.

7. International Agency for Research onCancer (1989) Diesel and gasolineengine exhausts and some nitroarenes,Vol. 46. Monographs on the evaluationof carcinogenic risks to humans. WorldHeath Organization, InternationalAgency for Research on Cancer, Lyon,

France.8. California EPA (1998) Proposed

Identification of Diesel Exhaust as aToxic Air Contaminant Appendix III PartA: Exposure Assessment. CaliforniaEnvironmental Protection Agency.California Air Resources Board April 22,1998.

Occupational Safety and Health hasclassified diesel exhaust a potentialoccupational carcinogen. The World HealthOrganization recommends that urgentefforts should be made to reduce [dieselengine] emissions, specifically of particulates, by changing exhaust traintechniques, engine design and fuelcomposition. More recently, the USNational Institute For Environmental HealthSciences (NIEHS) added diesel particulateto its list of substances that are reasonablyanticipated to be human carcinogens in its9th National Toxicology Report onCarcinogens.

Based on the available information, EPAconcluded that diesel particulate is aprobable human carcinogen. The mostcompelling information to suggest acarcinogenic hazard is the consistentassociation that has been observed betweenincreased lung cancer and diesel exhaustexposure in certain occupationally exposedworkers working in the presence of dieselengines. Approximately 30 individualepidemiological studies show increased lungcancer risks of 20 to 89 percent within the

study populations depending on the study.In mid October of 2000, the Clean Air Science Advisory Committee approved thisreport subject to minor changes in the text.

D. THE MATES STUDY OF TOXICITYThe toxicity problems associated with dieselparticulate was brought into sharp focus inthe Multiple Air Toxics Exposure Study(MATES-II), a landmark urban toxicsmonitoring and evaluation study conductedfor the South Coast Air Basin (Basin). It

represents one of the most comprehensiveair toxics programs ever conducted in anurban environment and contained severalelements - a comprehensive monitoringprogram, an updated emissions inventory of toxic air contaminants, and a modeling effortto fully characterize Basin risk.


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In the monitoring program, over 30 air pollutants were measured including bothgases and particulates.

The key result of the MATES-II study wasthat the average carcinogenic risk due to air pollution in the Basin is very high, about1,400 per million people. Mobile sources(e.g., cars, trucks, trains, ships, aircraft, etc.)represent the greatest contributor. About70% of all risk is attributed to dieselparticulate emissions; about 20% to other toxics associated with mobile sources(including benzene, butadiene, andformaldehyde); about 10% of all risk isattributed to stationary sources (which

include industries and other certainbusinesses such as dry cleaners andchrome plating operations.)

E. ULTRAFINE PARTICLESAnother aspect of diesel particulate thatcontinues to be a cause for concern is itssize. Approximately 80-95 percent of dieselparticle mass is in the size range from 0.05-1.0 micron with a mean particle diameter of about 0.2 microns. These fine particles havea very large surface area per gram of mass,

which make them excellent carriers for adsorbed inorganic and organic compoundsthat can effectively reach the lowest airwaysof the lung. The number of ultrafine particlesfrom a conventional diesel is roughly 2 to 3orders of magnitude greater than from acomparable gasoline fueled vehicle.However, the data also indicates that if aparticulate trap is used the number of ultrafines comes down even below gasolinefueled vehicles.

Approximately 50-90 percent of the number of particles in diesel exhaust is in the ultrafine size range from 0.005-0.05 microns,

averaging about 0.02 microns. Whileaccounting for the majority of the number of particles, ultra fine diesel particulate matter only accounts for 1-20 percent of the massof diesel particulate matter.

In a recent study in Germany, levels of bothfine and ultrafine particles were associatedwith increased mortality. In the HEI fundedstudy, Erich Wichmann and colleaguescharacterized the sizes of particles in theambient air of Erfurt, Germany, and

determined whether they were related tochanges in daily mortality 9. They reportedthat over a three-year period theconcentrations of both ultrafine (PM< 0.1)and fine particles (PM0.12.5) wereassociated with increased daily mortality.

These findings provided the first evidencethat ultrafine particles were associated withhuman mortality, but did not indicate

9. Wichmann H-E, Spix C, Tuch T, WlkeG, Peters A, Heinrich J, Kreyling WG,Heyder J. 2000. Daily Mortality and Fineand Ultrafine Particles in Erfurt,Germany. Part I: Role of ParticleNumber and Particle Mass. ResearchReport 98. Health Effects Institute,Cambridge MA.


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whether ultrafine particles were more toxicthan larger particles.

In another HEI study, Morton Lippmann andcolleagues compared day-to-dayfluctuations in hospital admissions of older people and deaths in the Detroit-Windsor area with day-to-day fluctuations in levels of different ambient PM size fractions 10 . Theyfound that four of the five size fractions theyevaluated were associated with increasedmorbidity and mortality. These were totalsuspended particles (TSPs; i.e., all particletypes and sizes up to about 40 m inaerodynamic diameter found in ambient air);PM10; PM0.12.5 (i.e., particles between

2.5 m and 10 m in aerodynamicdiameter); and PM2.5. The magnitude of theassociation was similar for all four fractions.The largest particle size fraction (between10 m and about 40 m) was not associatedwith increased morbidity and mortality. Theinvestigators also reported that the particlesfractionated by size were more significantlyassociated with health outcomes than werethe two chemical components of ambientPM, acidity and sulfate, evaluated in thestudy.

Mechanistic studies using animal subjects,and in vitro studies have also shown thatcompounds of transition metals in ultrafineform can generate so-called oxidative stressin the respiratory system 11 . However there isstill more work to be done to demonstratesimilar activity in ambient ultrafine particles.

Ultrafine particles are difficult to measure ona routine basis, but the UK DETR research

10. Lippmann M, Ito K, Ndas A, Burnett RT.2000. Association of Particulate Matter Components with Daily Mortality andMorbidity in Urban Populations.Research Report 95. Health EffectsInstitute, Cambridge MA.

11. K Donaldson et al, J Aerosol Sci1998;29:553-60.

program has been making suchmeasurements for the last few years at threesites (London curbside, London backgroundand rural Oxfordshire). While it is too early toquantify contributions precisely, it is clear that motor vehicles are proportionally amuch larger source of ultrafines than theyare of PM10, and probably PM2.5. 12

Available data indicates that exposure toultrafines is greatest in the first 300 metersfrom a major source, with levels decreasingto ambient upwind concentrations atdistances greater than 300 minutes.

There still remain many uncertainties and

unknowns in the science of ultrafineparticles, not least on the health effects andthe identification of the harmful componentsin the particles mix. However the evidencefor the link between health and ultrafines isbeginning to accumulate. On theprecautionary principle therefore, it would beprudent for regulators to consider how anydecisions taken now on related issues mightaffect ultrafines in the future. To the extentthat particle filters are used to comply withPM mass standards, the concern with ultra

fines will likely diminish since these systemshave been shown to dramatically reduceultra fines as well as total mass. However, tothe extent that new vehicles can comply withstandards without the use of the filteringsystems, as is increasingly likely in Europe,it is likely that pressure will continue to adoptadditional standards to assure that they areintroduced.

The issue of ultra fine particles appears tohave influenced the EU Council of

Environment Ministers when they indicatedfollowing their December 2000 meeting thatthey are interested in lowering sulfur levels,

12. ULTRAFINE PARTICLES-SCIENCESIGNALS AND POLICY MESSAGES,Dr Martin Williams, DETR, UK, July 2000


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seasonal, and yearly differences in ozoneconcentrations and differences from city tocity. Many of the chemical reactions that arepart of the ozone-forming cycle are sensitiveto temperature and sunlight. When ambienttemperatures and sunlight levels remainhigh for several days and the air is relativelystagnant, ozone and its precursors can buildup and produce more ozone than typicallywould occur on a single high temperatureday. 17 Further complicating matters, ozonealso can be transported into an area frompollution sources found hundreds of milesupwind, resulting in elevated ozone levelseven in areas with low VOC or NOxemissions.

Based on a large number of recent studies,several key health effects caused whenpeople are exposed to levels of ozone foundtoday in many areas have been identified. 18, 19

i. Health Effects From Short- Term Exposures to Ozone

A large body of evidence shows that ozonecan cause harmful respiratory effectsincluding chest pain, coughing, andshortness of breath, which affect people withcompromised respiratory systems mostseverely. When inhaled, ozone can causeacute respiratory problems; aggravateasthma; cause significant temporary

17. There is a growing concern that climatemodification resulting from the increasedbuildup of greenhouse gases such ascarbon dioxide may increase the amountof ozone produced from a given amountof NOx and VOCs.

18. U.S. EPA, 1996, Review of NationalAmbient Air Quality Standards for Ozone, Assessment of Scientific andTechnical Information, OAQPS Staff Paper, EPA-452/R-96-007.

19. U.S. EPA, 1996, Air Quality Criteria for Ozone and Related PhotochemicalOxidants, EPA/600/P-93/004aF.

decreases in lung function of 15 to over 20percent in some healthy adults; causeinflammation of lung tissue; may increasehospital admissions and emergency roomvisits; and impair the body's immune systemdefenses, making people more susceptibleto respiratory illnesses. Children andoutdoor workers are likely to be exposed toelevated ambient levels of ozone duringexercise and, therefore, are at greater risk of experiencing adverse health effects.

Short-term exposures (1-3 hours) to highambient ozone concentrations have beenlinked to increased hospital admissions andemergency room visits for respiratory

problems. For example, studies conductedin the northeastern U.S. and Canada showthat ozone air pollution is associated with10-20 percent of all of the summertimerespiratory-related hospital admissions.Repeated exposure to ozone can makepeople more susceptible to respiratoryinfection and lung inflammation and canaggravate preexisting respiratory diseases,such as asthma. Exposure to ozone cancause repeated inflammation of the lung,impairment of lung defense mechanisms,

and irreversible changes in lung structure,which could lead to premature aging of thelungs and/or chronic respiratory illnessessuch as emphysema, chronic bronchitis andchronic asthma.

Children are most at risk from ozoneexposure because they typically are activeoutside, playing and exercising, during thesummer when ozone levels are highest. For example, summer camp studies in theeastern U.S. and southeastern Canada have

reported significant reductions in lungfunction in children who are active outdoors.Further, children are more at risk than adultsfrom ozone exposure because their respiratory systems are still developing.Adults who are outdoors and moderatelyactive during the summer months, such as


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construction workers and other outdoor workers, also are among those most at risk.These individuals, as well as people withrespiratory illnesses such as asthma,especially asthmatic children, canexperience reduced lung function andincreased respiratory symptoms, such aschest pain and cough, when exposed toozone during periods of moderate exertion.

Evidence also exists of a possiblerelationship between daily increases inozone levels and increases in daily mortalitylevels. While the magnitude of thisrelationship is still too uncertain to allow for direct quantification, the full body of

evidence indicates a likely positiverelationship between ozone exposure andpremature mortality.

ii. Health Concerns fromProlonged and Repeated Exposures to Low Levels of Ozone

A large body of scientific literature regardinghealth and welfare effects of ozone hasassociated health effects with certainpatterns of ozone exposures that do notinclude any hourly ozone concentrationabove the 0.12 parts per million (ppm) levelof the 1-hour US NAAQS. The scienceindicates that there are health effectsattributable to prolonged and repeatedexposures to lower ozone concentrations.Studies of 6 to 8 hour exposures showedhealth effects from prolonged and repeatedexposures at moderate levels of exertion toozone concentrations as low as 0.08 ppm.

Studies of acute health effects have showntransient pulmonary function responses,transient respiratory symptoms, effects onexercise performance, increased airwayresponsiveness, increased susceptibility torespiratory infection, increased hospital andemergency room visits, and transientpulmonary respiratory inflammation. Such

acute health effects have been observedfollowing prolonged exposures at moderatelevels of exertion at concentrations of ozonewell below the current standard of 0.12 ppm.The effects are more pronounced atconcentrations above 0.09 ppm, affectingmore subjects or having a greater effect ona given subject in terms of functionalchanges or symptoms.

With regard to chronic health effects, thecollective data have many ambiguities, butprovide suggestive evidence of chroniceffects in humans. There is a biologicallyplausible basis for considering the possibilitythat repeated inflammation associated with

exposure to ozone over a lifetime, as canoccur with prolonged exposure to moderateozone levels below peak levels, may resultin sufficient damage to respiratory tissuethat individuals later in life may experience areduced quality of life, although suchrelationships remain highly uncertain.

iii. Other EffectsIn addition to the effects on human health,ozone is known to adversely affect theenvironment in many ways. These effectsinclude reduced yield for commodity crops,for fruits and vegetables, and commercialforests; ecosystem and vegetation effects insuch areas as National Parks; damage tourban grass, flowers, shrubs, and trees;reduced yield in tree seedlings and non-commercial forests; increased susceptibilityof plants to pests; materials damage; andvisibility.

3. JAPANESE COURT RULINGREGARDING HEALTH DAMAGE

Early in 2000, the Kobe District Courtordered the Japan central government andHanshin Expressway Public Corporation topay 210 million yen in compensation toresidents of Amagasaki, Hyogo Prefecture


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and take responsibility for pollution causedby vehicle exhaust emissions. 20 The courtruled that the onus is on the governmentand the corporation to keep the permissibledaily exposure to suspended particulatematter (SPM) at 0.15 milligrams per cubicmeter or less.

4. GOVERNMENT RESPONSES

As a result of the forces described above adverse health effects, environmentaldamage, potential impacts on globalwarming, legal challenges - governmentregulators have continued to dramaticallytighten exhaust emissions standards. In aneffort to enable manufacturers to achievethese very low pollution levels, fuel qualityimprovements, especially with regard tosulfur content are also being mandated.Restrictions have not been limited to newvehicles and engines, either, as many areasare now aggressively pursuing retrofitprograms for existing vehicles. In somecases, efforts have been directed atrestricting the use of existing diesels or evenbanning them.

A. UNITED STATES

i. Heavy Duty Vehicle And Engine And Diesel Fuel Requirements

EPA has also put in place a strategy tosignificantly reduce emissions from on-highway heavy-duty vehicles. The firstphase of the strategy takes effect startingwith the 2004 model year; the second phasein 2007. Several of the provisions included

in the new program are based on elementsof the Consent Agreement previouslynegotiated between most of the major US

20. /Govt to cough up over air pollution,Mainichi Shimbun, February 1, 2000

diesel engine manufacturers and the USDepartment of Justice. 21

Phase One - On August 1, 2000, US EPA

Administer Browner signed a Final Ruleregarding the 2004 standards for heavy-dutyvehicles and engines. 22 The Final Ruleconcludes that the previously adopted 2004NMHC+NOx standard for heavy-duty dieselengines (HDDEs) is technologically feasible,cost-effective, and appropriate under theClean Air Act, in the context of the currentPM standard. This includes a finding that achange in diesel fuel formulation is notrequired to meet these standards.

In addition, the Rule finalizes a new set of supplemental test procedures to moreclosely represent the range of real worlddriving conditions of heavy-duty dieselengines. These elements are specificallydesigned to provide additional certainty thatthe standards will be met under a widerange of operating conditions. Theseelements apply to all heavy-duty dieselengines, except those in Medium-dutyPassenger Vehicles, which are subject tothe Tier 2 program. (See discussion above)

First, EPA is adding a steady-state testrequirement to the current Federal testprocedures (FTP) for HD diesel engines.Emission results from this test must meetthe numerical standards for the pre-existingFederal test procedure (i.e., the NMHC+NOxstandards noted above, a CO standard of 15.5 g/bhp-hr, and a PM standard of 0.10

21. See Global Trends in Diesel EmissionsControl - A 1999 Update, SAE Paper #1999-01-0107.

22. The majority of the seven HDEmanufacturing companies covered bythe U.S. Department of Justice NOxconsent decree have agreed to produceengines beginning in October 2002 thatwill meet the applicable NOx+NMHCstandard over the expanded certificationtest procedure.


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g/bhp-hr). This steady-state test requirementbecomes effective starting with the 2007model year. Second, EPA also finalized Not-to-Exceed (NTE) test procedures for testingof in-use engines. These NTE proceduresapply under any conditions that couldreasonably be expected to be seen innormal vehicle operation and use, includingan expanded range of ambient conditions.Emission results from this test proceduremust be less than or equal to 1.25 times thepre-existing Federal test procedurestandards. The NTE test and associatedemission limits are effective starting with the2007 model year. Third, EPA finalized aLoad Response Test (LRT) certification data

submittal requirement, effective starting withthe 2004 model year.

Phase Two - On December 21, 2000, EPAadopted a final rule regarding tighter NOxand particulate standards for heavy-dutytrucks and low sulfur diesel fuel. Keyprovisions are summarized below:

Low Sulfur Fuel Requirements - Asproposed, the maximum sulfur level in dieselfuel will be reduced to 15 PPM by July 1,

2006. Within each region of the country (socalled PADDs) refiners and distributors willbe allowed to produce and sell up to 20% of their fuel at the current level (maximum of 500 PPM) to minimize any risk of supplydisruptions; this exemption will expire by theend of 2009, by which time 100% of the fuelmust meet the 15 PPM requirement.

Small refiners, which sell approximately 5%of the diesel fuel across the country, arealso allowed to delay producing the low

sulfur fuel until 2010. However, in order toencourage the small refiners to provide thelow sulfur diesel fuel in 2006, EPA will offer them the option of either delaying the lowsulfur diesel until 2010 or delaying theproduction of low sulfur gasoline (which wasrequired by the Tier 2 package a year ago)

until 2010; EPA expects that many smallrefiners will choose the gasoline option.

Overall, EPA expects that about 90% of all

diesel fuel sold in the country by mid 2006will be low sulfur and that this will risegradually to 100% by 2010.

Heavy Duty Engine Emissions Standards- A particulate standard of 0.01 grams per brake-horsepower hour will go into effect on100% of new heavy-duty diesel engines in2007. The new NOx standard of 0.2 gramsper brake-horsepower-hour will be phased in- 50% of the engines sold by eachmanufacturer must meet the standard in

each of model years 2007, 2008 and 2009and then 100% in 2010.

With respect to PM, this new standardrepresents a 90 percent reduction for mostheavy-duty diesel engines from the currentPM standard and is projected to require theaddition of highly efficient PM traps to dieselengines, including those diesel enginesused in urban buses.

The new NOx standard is projected to

require the addition of a highly efficient NOxemission control system to diesel engines.

In addition to the new FTP standards for HDdiesel engines, EPA also adoptedsupplemental emission standards to helpensure that HD diesel engines achieve theexpected in-use emission reductions over awide range of vehicle operation and a widerange of ambient conditions, not only thetest cycle and conditions represented by thetraditional FTP. The supplemental provisions

for HD diesel engines consist of twoprincipal requirements, the supplementalemission test and associated standards(SET), and the not-to-exceed test andassociated standards (NTE).


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B. CALIFORNIAThe California Air Resources Board (ARB)has released its risk reduction plan thatoutlines strategies to require particulatematter (PM) traps on all new and mostexisting diesel engines in California. Dieselengines that are affected by the proposalinclude heavy-duty trucks and buses,construction equipment, passenger vehiclesand trash haulers, generators, agriculturaland marine engines.

The ARB estimates that about 27,000 tonsof diesel PM are emitted each year intoCalifornias air. The staff proposal calls for ARB to work with local and federal agencies,engine manufacturers, fuel providers andthe public to develop additional emissionstandards to reduce diesel emissions by upto 90 percent from the 1.25 million dieselengines in the state.

The plan calls for 12 control measures to beadopted within one to five years, with fullimplementation by 2010. Some of thestrategies proposed in the plan consist of equipping all new diesel engines with PMtraps, requiring low-sulfur diesel fuel, in-use

emission testing, broader use of alternativefuels and providing funding to offset the costof upgrading to cleaner alternative fuelengines. The plan also recommendsretrofitting existing diesel engines with PMtraps.

C. EUROPEAN UNION

i. HEAVY DUTY VEHICLES AND ENGINES

The European Parliament approved newrules to limit emissions from trucks andbuses, paving the way for a final EuropeanUnion accord in December 1999. Theassembly voted to approve standards

agreed earlier in 1999 by EU environmentministers. 23

The final package requires engines to be

tested on both the steady state and transientcycles except gas engines, which are onlytested on the ETC cycle. The limit values for Enhanced Environmentally Friendly Vehicles(EEV's) are 2.0 g/kWh NOX and 0.02 g/kWhPM on both cycles. These standards shouldserve as the basis for voluntary purchasesof urban vehicles such as buses.

The Heavy-duty directive 1999/96/ECenvisages the adoption of further measuresto take effect from 2005/6. These are:

Provisions relating to thedevelopment of on-board diagnostic(OBD) and on-board measurement(OBM) systems to monitor in-serviceexhaust emissions

Durability requirements and in-service control

Limits for non-regulated pollutantsthat may become important as a

result of the widespread introductionof new alternative fuels.

In addition the Commission was to report by31 December 2002 on the current status of technology needed to meet the mandatoryNOx standard for 2008. The report is almostcompleted and will likely conclude that the2008 standards are feasible.

Many if not most manufacturers areexpected to be able to meet the Euro 4standards without diesel particulate filters(DPFs). While it looks today as if someheavy-duty engines will require traps to

23. See Global Trends in Diesel EmissionsControl - A 1999 Update, SAE Paper #1999-01-0107.


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comply with the 2008 standards,manufacturers are working hard to avoidthem and they may succeed. At the sametime pressure is building within the EU torequire or at a minimum allow member states to incentivize these PM controlsystems. Approximately a year ago, Swedenrequested authority to move in this directionor to have the Directive provision whichprohibits incentives for standards beyondthose adopted by the EU amended. Therequest was denied. However, recentlyFrance and Germany have sent a letter tothe Commission raising several additionalpoints:

In spite of the significant improvement indiesel vehicle emissions, a substantialproblem remains with both PM and NOx.They note that the WHO, the EUCommission, the National ResearchCouncil and the US EPA have allidentified fine particulate as a high priorityproblem because of its roles in causingrespiratory problems, heart disease andpremature mortality.

Air quality measurements show that the

number of particles in the size range of 0.01 to 2.5 m are high and have notdeclined in the past six years. InGermany, it is estimated that in theproximity to traffic, traffic emissionscontribute 45% to 65% of the particle loadof the breathing air.

The portion of new diesel car registrations has more than doubled inrecent years and is now at approximately40% and while this technology has clear

CO2 advantages it will result in PMemissions 60% higher than previouslyestimated in 2020.

NOx reductions are also urgentlyneeded to reduce the ozone burden. Amodern diesel passenger car discharges

about eight to ten times as much NOx asa petrol fueled car.

It now appears that Euro IV for cars andEuro V for trucks can largely be metwithout PM filters; a further tightening of the limit values is needed to require thishighly efficient technology and itsassociated health benefits.

Particle filters are demonstrated to beavailable and effective under practicalconditions as over 270,000 cars and morethan 50,000 commercial vehicles arecurrently so equipped.

The future US limits for commercialvehicles are approximately 90% lower for NOx and 60% lower for PM than Euro Vlimits. Tier 2 limit values for NOx and PMare approximately 80% lower than Euro IVcar limits. Japanese PM limits approachzero.

In this context, France and Germany calledupon the Commission to submit by mid 2004suggestions on the updating of 98/69/EGand 99/96/EG with the goal of further NOxand PM reductions using the possibilities of the particle filter technology. Germany andFrance will support this work with all their efforts.

In light of these developments and in view of further work being carried out at the GRPEregarding test procedures and equipment tomeasure ultrafine particles, which is due tobe completed by mid year, the Commissionis beginning to consider several alternativeapproaches. These include:

Adopting enhanced environmentallyfriendly vehicle limits which could be usedby member states with tax incentives toencourage the early introduction of vehicles with PM filters, or


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Adopting Euro V limits for light dutyvehicles which would include lower NOxlevels and possibly a PM number limit, or

Further tightening the PM or NOx limitsfor heavy commercial vehicles as part of the Euro V technology review, or

All of the above.

ii. NEAR ZERO SULFUR FUELThe Commission was required to bringforward a proposal to define the remainingfuel parameters that have not already beenestablished to take effect from 1 January

2005. In May 2000 the Commissioner for Environment launched a "Call for Evidence"on whether petrol and diesel fuels withsulphur contents less than 50 parts per million (ppm) should be available on aEuropean Union basis. She noted thatdevelopments in the marketplace andparticularly with respect to the evolution of diesel and petrol fueled engines and their emission abatement technologies suggestthat there may be additional benefits for fuelwith a sulphur content that is lower than 50parts per million to be available. There hadbeen much discussion surrounding theappropriate sulphur content of petrol anddiesel fuels and its potential contribution inmeeting environmental emission targets for nitrogen oxides, particulate matter andcarbon dioxide. The Commission decided,therefore, to conduct a consultation exerciseto inform itself as to whether petrol anddiesel with a sulphur content of less than 50parts per million should be available on aCommunity wide basis.

After receiving comments from a broadcross section of stakeholders, theCommission proposed new legislation tophase out sulphur in petrol and diesel by2011. As part of the European Union'songoing strategy to reduce harmful

pollutants and carbon dioxide (CO2) fromcars, the law would require every EUcountry to ensure that sulphur free petroland diesel are available from 2005.

The European Union recently completedpassage of the law, requiring much lower amounts of sulphur in petrol and diesel by2005, with a total phase in of "sulphur free"fuels by 2009. The European Parliamentvoted Jan. 30 to set a deadline of Jan. 1,2009, for an EU-wide changeover to "zerosulfur" gasoline and diesel fuels used in roadtransport, and the Council of Ministersapproved the measure Feb. 7.

Limiting sulfur content to 10 parts per million(ppm) will allow industry to develop newgenerations of "lean burn" (fuel-efficient)engines and improve the efficiency of catalytic exhaust gas converters, accordingto EU Environment Commissioner MargotWallstrm. Zero-sulfur road fuel also willhelp the EU reach its goal of reducingcarbon dioxide emissions from new cars to120 grams per kilogram of fuel on average.

The approval came nearly two months after

the Parliament and Council of Ministersreached agreement on the issue the EU'sConciliation Committee, where legislativedifferences between the two institutions areresolved.

The final text also provides for review by2006 of the purity standards of fuel used by"non-road mobile machinery," such astractors used in farming and forestry, andconstruction equipment such asearthmovers and bulldozers.

Meanwhile, the new legislation will requirethe oil industry to ensure that by 2005 zero-sulfur fuels are available across Europe on a"sufficiently balanced geographical basis" toallow drivers to refuel without having to drivelong distances.


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A further amendment secured by theParliament will require Wallstrm to reviewtechnical issues regarding fuel quality in lightof EU moves to encourage use of biofuels.As part of the 2005 review of fuel qualitystandards, the European Commission hasbeen instructed to look at the case for changing EU rules on fuel volatility tofacilitate sales of environmentally friendlier blends of gasoline and bioethanol. Currently,straight blends of the two fuels riskcontravening EU rules on volatility,particularly in high temperatures.

D. JAPANi. CURRENT REQUIREMENTS

In spite of the significant pollution controlefforts to date in Japan, the NO 2, O 3 andparticulate problems in major cities remainserious. Therefore, the Japanese EPA hasmoved forward with their regulation of dieselvehicles. On December 14 th , 1998, the Air Quality Committee, Central Council for Environmental Pollution Control issued thenew Short Term Targets for diesel vehiclepollution control.

With these short-term targets, NOxemissions will be reduced by 25 to 30percent and particulate matter by 28 to 35percent over a period from the year 2002 to2004. Moreover, with a view to maintainingadequate performance of exhaust emissionscontrols in use, the durability requirementswill be extended and the installation of OBDsystems will become mandatory.

Expected control technologies includeoxidation catalysts, cool EGR, high-pressurefuel injection, intercooling andTurbocharging.

ii. EMERGING DEVELOPMENTS

Serious and growing concerns regardingdiesel vehicle emissions have, however,accelerated the process. In mid 1999, theGovernor of Tokyo launched a campaign toban diesels entirely from the city of Tokyobecause of persistently high levels of NO2and growing concerns over the healtheffects of diesel PM. Then on January 31,2000, the Kobe District Court ordered thegovernment and Hanshin ExpresswayPublic Corporation to pay for the healthdamages to the plaintiffs who were residentsin the roadside area of National HighwayNo. 43 and Hanshin Expressway. 24 In thefinding, the Court acknowledged therelationship between asthma of the plaintiffsand suspended particulate matter (SPM),especially diesel exhaust particulate (DEP).The Court also ruled that the governmentand Hanshin Expressway should keep theSPM concentration level lower than0.15mg/m3 within 50m from the roadside of both roads.

Subsequently, the Tokyo MetropolitanGovernment announced on 18 February thedraft regulations for the mandatoryinstallation of Diesel Particulate Filters (DPF)for all diesel vehicles that run in the Tokyoarea. The government proposed to amendits anti pollution law by the end of 2000 torequire particulate retrofitting of all existingdiesel engines. The new regulation will beeffective on April 1, 2001. There will be a 2-year's preparation time for retrofit, so thefirst group under the regulation is required tobe equipped with diesel particulate filters(DPFs) after April 2003. The requirements

will be phased in on a step-by-step basis but100% of the vehicles are to be equippedwith DPF by April of 2006.

24. Govt to cough up over air pollution,Mainichi Shimbun, February 1, 2000


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Approximately 190,000 diesel passenger cars and 460,000 commercial vehicles areregistered in Tokyo. In addition to those,about 240,000 diesel vehicles come intoTokyo from other areas each day.

The Diesel Advisory Committee developedits recommended retrofit program at ameeting on May 18 th and released it publiclyon June 11 th . In summary, if a 1989 truck or bus wishes to operate in Tokyo in 2003 and2004, it must be equipped with a PM controldevice that reduces emissions by aminimum of 60%. In 2005, all these trucksmust be off the road but diesel buses whichwish to continue to operate must have a

device installed which results in a minimumPM reduction of 70%.

If a 1994 truck or bus wishes to operate in2003 and 2004, it must have a deviceinstalled that would have reduced itscertification level to 0.25 g/Kw-hr. For example, if the particular engine familycertified to a level of .69, it would need toinstall a device that reduced PM by 64%([0.69-0.25]/0.69). To operate beyond 2005it must have a device that reduces PM by at

least 74%.

Japan's Central Environmental Council onMarch 7, 2002 released for public commentnew, more stringent requirements on tailpipeemissions for new motor vehicles to be soldin 2005 and later, including foreign-manufactured vehicles. The interim finalregulation issued for comment applies bothto gasoline- and diesel-powered passenger cars, trucks, and buses and sets differentrequirements for different classes of

vehicles.

The new regulation calls for reducing PMemissions from trucks and buses by up to 85percent and NOx emissions by 50 percentfrom the levels set in the short-term dieselauto emission regulation. Domestic products

and imported vehicles that fail to meet theregulation cannot be registered for use inJapan.

The Japanese New-Long-Term Regulations,decided on March 5, will start from October 2005. The test mode will be also changed;transient mode will replace the steady statemode.

E. OFF ROAD VEHICLES ANDENGINES

Because emissions from on road vehiclesand engines are largely controlled, at leastfor CO, HC, NOx and PM, governmentsaround the world are increasingly noting theimportant remaining role that non-roadengines can play in the air pollution problem.According to one recent estimate, there areover 140 million off road vehicles andengines in the US alone, a potentiallyimmense pollution control market. 25 However, the market has not evolved as fastas it could due to the inability to resolvedifficult regulatory issues to date. This couldchange dramatically in the next year as EPAhas indicated its intention to develop a rulewhich could require the same degree of control for off road heavy duty dieselengines as has been adopted for on road.

Nonroad HDDEs represent a substantial andgrowing share of the emissions inventoriesfor both oxides of nitrogen (NO x) andparticulate matter (PM) thus posing asubstantial threat to public health. In fact,emissions from HDDEs are at least equal to,

25 Nonroad Engine Population Estimates,Report No. NR-006A , December 9, 1997,revised June 15, 1998, Christian E.Lindhjem, Nonroad Emissions ModelingTeam, Assessment and Modeling Division,US EPA, Office of Mobile Sources.


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if not several times greater than, emissionsfrom on road HDDEs in many countries.

Compared to highway vehicles, emissionsfrom nonroad equipment are relatively under controlled. Given the current inequity inemission control requirements and theavailability of known control technologiesand strategies, reducing emissions from thissource sector could represent one of themore cost-effective available control options.

5. CONCLUSIONSDiesel technology has improvedsubstantially in recent years. In somecountries this has resulted in large increasesin light duty diesel sales and heavy dutytrucks worldwide are almost all diesel fueled.However, while the fuel economy anddurability advantages of the diesel are wellunderstood and appreciated, environmentalregulators are increasingly concerned aboutdiesel emissions. They are driven primarilyby health concerns as there have been asteady stream of studies highlighting theneed to further reduce diesel PM and NOxemissions. As a result, the US (includingespecially California), Europe and Japanhave all substantially tightened dieselemissions requirements in recent years.Diesel fuel sulfur levels have also beenreduced.

Growing attention has also been focused onemissions from existing in use vehicles andnumerous cities and countries are activelypursuing diesel PM retrofit strategies.

Finally, the nonroad sector is an increasinglyimportant source of emissions and is onlynow beginning to get the kind of regulatoryattention that it deserves.


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1. INTRODUCTION 1 2. HEALTH AND ENVIRONMENTALCONCERNS ABOUT DIESEL PM EMISSIONS----------------------------------------------------------------1 A. NEW US PARTICULATE STUDIES ------------------------------------------------------------------ 2

i. The Particle EpidemiologyReanalysis Project----------------------------------------------------------------------------------------------- 2 ii. The National Morbidity, Mortalityand Air Pollution Study (NMMAPS) ------------------------------------------------------------------------- 3 iii. Update of ACS Study ---------------------------------------------------------------------------------- 3

B. EUROPEAN PM STUDY--------------------------------------------------------------------------------- 5 C. DIESEL TOXICITY ---------------------------------------------------------------------------------------- 6 D. THE MATES STUDY OFTOXICITY------------------------------------------------------------------------------------------------------------- 6 E. ULTRAFINE PARTICLES-------------------------------------------------------------------------------- 7

F.

GLOBAL WARMING IMPACT OFBLACK CARBON --------------------------------------------------------------------------------------------------- 9 G. HEALTH AND ENVIRONMENTALIMPACTS FROM PHOTOCHEMICALOXIDANTS (OZONE)---------------------------------------------------------------------------------------------- 9

i. Health Effects From Short-TermExposures to Ozone--------------------------------------------------------------------------------------------10 ii. Health Concerns from Prolongedand Repeated Exposures to Low Levelsof Ozone-----------------------------------------------------------------------------------------------------------11

3. JAPANESE COURT RULING REGARDINGHEALTH DAMAGE 11 4. GOVERNMENT RESPONSES----------------------------------------------------------------------------- 12

A. UNITED STATES -----------------------------------------------------------------------------------------12 i. Heavy Duty Vehicle And EngineAnd Diesel Fuel Requirements ------------------------------------------------------------------------------12

B. CALIFORNIA-----------------------------------------------------------------------------------------------14 C. EUROPEAN UNION -------------------------------------------------------------------------------------14

i. HEAVY DUTY VEHICLES ANDENGINES -------------------------------------------------------------------------------------------------------14 ii. NEAR ZERO SULFUR FUEL--------------------------------------------------------------------------16

D. JAPAN -------------------------------------------------------------------------------------------------------17 i. CURRENT REQUIREMENTS -------------------------------------------------------------------------17 ii. EMERGING DEVELOPMENTS-----------------------------------------------------------------------17

E. OFF ROAD VEHICLES ANDENGINES ------------------------------------------------------------------------------------------------------------18

5. CONCLUSIONS 19

heavy duty diesel pollu

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