Testimony of

Daniel S. Greenbaum, President

Health Effects Institute

on:

The Health Effects of Air Emissions

from the Transportation Sector

Before the:

Committee on Environment and Public Works

United States Senate

August 1, 2001

Chairman Jeffords, and members of the Committee, thank you for the opportunity to testify before you today on the health effects of air emissions from the transportation sector. I come before you as the President of the Health Effects Institute, a non-profit, independent research institute funded jointly and equally by the US EPA and the worldwide motor vehicle industry to provide high-quality, impartial science on the health effects of emission from transportation and other sources in the environment. For over two decades, we have conducted targeted research on the full range of emissions and health effects, and I am pleased to summarize our understanding for you today. For the record, I have also submitted a more detailed paper that describes these effects and trends.

Since the early 1970s, as vehicle travel has grown dramatically, there have been concerns about air pollution from transport and its impacts on human health. There has been substantial progress to reduce the emissions from individual vehicles, and more recently improvements in the quality of fuel, resulting in reductions of some emissions by greater than 90%. At the same time, traffic volume has grown substantially, offsetting much of the improvement achieved. Also, scientific knowledge has increased, identifying health effects from emissions from motor vehicles at lower levels of exposure. Thus there continues today to be significant attention to understanding the health effects of, and reducing the emissions from, vehicles and fuels.

Emissions

The combustion of gasoline and diesel fuel in vehicle engines produces a number of emissions of potentially harmful substances. These emissions are not solely the result of the combustion process, nor do they come only from the tailpipe of the vehicle. Rather, such emissions result from a combination of the engine design and the fuel characteristics. Evaporative emissions - from refueling, spills on to heated engine parts, etc. - can equal emissions from the tailpipe.

The emissions from motor vehicles come in two primary forms: major gaseous and particulate air pollutants which can be found in relatively high amounts in the atmosphere, and air toxics which usually are found in lower amounts in the atmosphere but can have important health impacts. The gaseous and particulate pollutants to which motor vehicles contribute include carbon monoxide, ozone (through its atmospheric precursors volatile organic compounds (VOCs) and nitrogen oxides (NOx)), fine particulate matter PM₁₀ and PM _2.5 (particles smaller than 10 and 2.5 microns in aerodynamic diameter respectively), and nitrogen dioxide. The air toxics emitted from motor vehicles include aldehydes (acetaldehyde, formaldehyde, and others), benzene, 1,3-butadiene, and a large number of substances known as polycyclic organic matter (including polycyclic aromatic hydrocarbons, or PAHs).

All of the emissions from motor vehicles also come from other sources such as industrial processes, electric power generation, and home heating. As a result, the contribution of motor vehicles to ambient levels varies depending on the pollutant. In most cases, motor vehicles contribute between 25% and 40% of the ambient levels, although in a few cases (e.g. carbon monoxide, ultrafine particles (PM0.1), and 1,3-butadiene) motor vehicle contributions are noticeably higher.

To date, most of the attention to reducing emissions from transport has focussed on onroad cars and heavy-duty vehicles. Increasingly, we have understood that nonroad sources, including construction equipment, locomotives, airplanes and ships are also significant contributors to ambient air pollution, for some pollutants emitting amounts equal to or exceeding those from onroad sources.

Exposure

While in general motor vehicles contribute a significant portion, although not the majority, of most air pollutants, there are certain circumstances in which motor vehicles can contribute a substantially higher amount to personal exposure. In particular, in urban centers, along roadsides, and especially in urban street canyons in crowded business districts, mobile source contributions can contribute 2 to 10 times as much as in general background situations.⁽¹⁾ This can have important implications for the potential acute health effects from exposure to these pollutants and, if individuals spend a significant portion of their lives living in these environments, may result in greater contributions of vehicles to chronic health effects as well. This may be especially true for elderly, low-income, and other urban populations that could be sensitive to the effects of air pollution.

Effects

Research over the past several decades has found a variety of effects from the different pollutants, including effects on the lungs, heart, and nervous system, and the promotion of several different types of cancer. Overall, the effects of these pollutants on public health tend to be relatively small in comparison with other risk factors such as cigarette smoking, but because of the large number of people exposed the effects as a whole are of sufficient magnitude to be of public concern.

Despite some uncertainties, there is much known about the effects of each of these pollutants:

Carbon Monoxide is a gas emitted directly from vehicles. High levels of exposure are known to be lethal; low levels found in ambient settings are not likely to have effects in healthy individuals but may cause increased incidence of cardiac effects.

Ozone is known to reduce the lung function of some individuals and epidemiological studies have found evidence of increased asthma attacks and hospitalization related to increased ambient levels. A recent study conducted by the Centers for Disease Control in Atlanta before, during, and after the Olympics found both a distinct reduction in ozone levels resulting from the Olympics traffic reduction measures, and a coinciding reduction in childhood asthma hospitalization.

Particulate Matter in the form of PM10 and PM 2.5 is emitted directly from motor vehicles and other sources, and also formed in the atmosphere from atmospheric reactions with gaseous emissions (e.g. nitrogen oxides become nitrates). Although PM has been of concern for many decades, new studies published in the 1990s found associations of PM with increased mortality and morbidity at ambient levels.

In the past several years, several new epidemiologic studies have begun to strengthen the understanding of the relation between exposure to PM and mortality and morbidity. Recently, HEI's National Morbidity, Mortality, and Air Pollution Study, of the 90 largest cities in the United States, has found a generally consistent effect of PM and mortality, when common methods are applied, and after the effects of other pollutants are considered. HEI's Reanalysis of the Harvard Six Cities and American Cancer Society Studies has also reported on extensive additional analysis of these two studies that have been the basis of most U.S. and European efforts to estimate the population health effects of PM, and have generally confirmed the results. HEI is currently investigating continuing questions about the nature and extent of PM health effects.

Components and Characteristics of the PM Mixture have been identified as potentially being most responsible for mortality and other risks. Diesel exhaust particulate matter has been cited as a probable human carcinogen by several national and international agencies. Hypotheses have also been put forward suggesting that ultrafine particles (less than 0.1 microns), particles containing metals (e.g. iron), and other types of particles may be the most toxic components of the mixture. To date these studies have not identified one component or characteristic that is significantly more toxic than others.

Air Toxics have a variety of characteristics and effects. Most of those emitted from motor vehicles are animal carcinogens. Benzene is a known human carcinogen. Butadiene, for which vehicles are the dominant ambient source, was recently designated as a probable human carcinogen by the International Agency for Research on Cancer and a known human carcinogen by the U.S. National Institutes of Health. Several aldehydes (including formaldehyde and acetaldehyde) have also been designated as probable human carcinogens.

Trends and the Future

Given the health effects of vehicle emissions, action has been taken, and continues to be taken to reduce emissions from both gasoline and diesel vehicles. The U.S. EPA took action in 1999 to further improve fuel formulation and reduce emissions of light duty vehicles (Tier 2), and in 2001 to promulgate stringent new fuel and emissions standards for heavy-duty vehicles. In addition, recent German government analyses determine that these requirements for a substantial reduction in diesel particulate matter emissions are expected to substantially reduce cancer risk from diesel.

However, continued growth in travel is expected to offset a portion of these reductions. As a result, continued attention to reducing emissions is likely in the future. This will come in three ways:

S continued tightening of fuel and emission standards for petrol and diesel vehicles ;

S introduction of new technologies: natural gas vehicles, electric and electric hybrid vehicles, and fuel cell vehicles are all in development or beginning to appear on the market. While these have certain air quality advantages, they may also raise new health questions (e.g. the use of methanol to power fuel cells), and will need to be introduced with appropriate care.

S policies to discourage growth in personal auto use - this is potentially the most important future direction, and at the same time the most challenging. Future land use and transportation policy can significantly affect travel behavior, but the ability to implement effective measures may be limited as the general public is increasingly used to and reliant upon the flexibility of the private automobile.

In conclusion, the emissions of a variety of pollutants from vehicles account for, in general, approximately 25% to 40% of the ambient levels of air pollution (and in some cases more, depending on the pollutant and location). These pollutants have been found to have a measurable effect on the public health. As a result, the long-term trend has been toward reducing emissions from motor vehicles, and that trend is likely to continue in the future. However, continued growth in vehicle travel is likely to offset at least a portion of the expected reductions, suggesting continued efforts to reduce the emissions and other impacts on public health.

Health Effects Institute

July 25, 2001

Transport and Human Health

Daniel S. Greenbaum

Health Effects Institute

Cambridge, Massachusetts USA

+1 617 886 9330

dgreenbaum@healtheffects.org

Concerns about ambient air pollution and public health first rose to broad public attention in the 1950's, following significant air pollution episodes in London, England, Donora, Pennsylvania, and elsewhere that were linked to noticeable increases in hospitalization and premature mortality. These incidents, which involved air pollution largely from industrial sources and home heating, presaged public policy action for the past four decades to reduce air pollution and improve public health. Increasingly during that time, as vehicle travel has grown dramatically, attention has focussed on air pollution from transport and its impacts on human health.

Beginning in the 1970s in the United States and in the 1980s in Europe, there has been substantial progress to reduce the emissions from individual vehicles, and more recently improvements in the quality of fuel, resulting in reductions of some emissions by greater than 90%. At the same time, traffic volume has grown substantially, offsetting much of the improvement achieved. Also, scientific knowledge has increased, identifying health effects from emissions from motor vehicles at lower levels of exposure. Thus there has been, and there continues today to be, significant public attention to reducing the emissions from vehicles and fuels, and their attendant affects on human health.

Since 1980, the Health Effects Institute has been producing extensive research on the health effects of air pollution from motor vehicles and other sources.⁽²⁾ We have learned much during that time about the emissions from vehicles, personal exposure to those emissions, and the resulting effects. This paper attempts to review briefly what we know about emissions, exposure, and effects, and to discuss current and likely future trends.

Emissions

The combustion of gasoline and diesel fuel in vehicle engines produces a number of emissions of potentially harmful substances. Increasingly we have understood that these emissions are not solely the result of the combustion process, nor do they come only from the tailpipe of the vehicle. Rather, it has become clear that such emissions result from a combination of the engine design and the fuel characteristics. Evaporative emissions - from refueling, spills on to heated engine parts, etc. - can equal emissions from the tailpipe.

The emissions from motor vehicles come in two primary forms: major gaseous and particulate air pollutants which can be found in relatively high amounts in the atmosphere, and air toxics which usually are found in lower amounts in the atmosphere but can have important health impacts. The gaseous and particulate pollutants to which motor vehicles contribute include carbon monoxide, ozone (through its atmospheric precursors volatile organic compounds (VOCs) and nitrogen oxides (NOx)), fine particulate matter PM₁₀ and PM _2.5 (particles smaller than 10 and 2.5 microns in aerodynamic diameter respectively), and nitrogen dioxide. The air toxics emitted from motor vehicles include aldehydes (acetaldehyde, formaldehyde, and others), benzene, 1,3-butadiene, and a large number of substances known as polycyclic organic matter (including polycyclic aromatic hydrocarbons, or PAHs).

All of the emissions from motor vehicles also come from other sources such as industrial processes, electric power generation, and home heating. As a result, the contribution of motor vehicles to ambient levels varies depending on the pollutant (see Table 1). In most cases, motor vehicles contribute between 25% and 40% of the ambient levels, although in a few cases (e.g. carbon monoxide, ultrafine particles (PM0.1), and 1,3-butadiene) motor vehicle contributions are noticeably higher.

Table 1. Contributions of Motor Vehicle Emissions to Ambient Levels of Major Air Pollutants

Exposure

While in general motor vehicles contribute a significant portion, although not the majority, of most air pollutants, there are certain circumstances in which motor vehicles can contribute a substantially higher amount to personal exposure. In particular, in urban centers, along roadsides, and especially in urban street canyons in crowded business districts, mobile source contributions can contribute 2 to 10 times as much as in general background situations.⁽³⁾ For example, while urban background levels of PM10 in England have been measured at 22 - 25 /m³, and at street side levels have been measured at 24 - 38 /m³ .(DETR 1999) This can have important implications for the potential acute health effects from exposure to these pollutants and, if individuals spend a significant portion of their lives living in these environments, may result in greater contributions of vehicles to chronic health effects as well. This may be especially true for elderly, low-income, and other urban populations that could be sensitive to the effects of air pollution.

Effects

Research over the past several decades has found a variety of effects from the different pollutants, including effects on the respiratory, neurological, and cardiac systems, and the promotion of several different types of cancer. One of the challenges of understanding these effects is that they are usually experienced as part of a complex mixture of pollutants, and it is often difficult to disentangle the specific effects of one pollutant from the effects of other pollutants that follow similar spatial and atmospheric patterns.(HEI 2000) At the same time, it is apparent that not all members of the population are equally sensitive to such effects, and that some subgroups (e.g. the elderly, asthmatics, children, people with heart disease) may at more risk from exposure to air pollution.

Overall, the effects of these pollutants on public health tend to be relatively small in comparison with other risk factors such as cigarette smoking, but because of the large number of people exposed the effects as a whole are of sufficient magnitude to be of public concern.

Despite some uncertainties, there is much known about the effects of each of these pollutants:

Carbon Monoxide is a gas emitted directly from vehicles. When inhaled it replaces oxygen in the bloodstream, forming carboxyhemoglobin and interfering with the normal transport of oxygen to the heart and brain. High levels of exposure are known to be lethal; low levels found in ambient settings are not likely to have effects in healthy individuals but can advance the time of angina (chest pain) in people with coronary artery disease and may cause increased incidence of cardiac effects. Some recent epidemiologic studies have found relationships between increased CO levels and increases in mortality and morbidity (EPA 2000).

Ozone is a gas formed in the atmosphere from combinations of nitrogen oxides and volatile organic compounds (both emitted from vehicles) in certain meteorologic conditions normally found in the summer time. It is known to reduce the lung function of some individuals, (see Figure 1) and epidemiologic studies have found evidence of increased asthma attacks and hospitalization related to increased ambient levels. It may also increase the lung's reaction to allergens and other pollutants. Although recent studies have found associations of daily increases in ozone with increased mortality, there is not comprehensive evidence that long-term exposure causes chronic health effects, and some evidence suggests that the lung may develop a form of tolerance after repeated

short-term exposures (EPAQS 1997, HEI, 1996).

Particulate Matter in the form of PM10 and PM 2.5 is inhalable material which is emitted directly from motor vehicles and other sources, and also formed in the atmosphere from atmospheric reactions with gaseous emissions (e.g. nitrogen oxides become nitrates). Although PM has been of concern for many decades, new short term and long-term epidemiologic studies published in the U.S. and Europe in the 1990s found associations of PM with increased mortality and morbidity at ambient levels below then-established national air quality limit values. It is these studies that have been the basis for recent action in both the European Union and the United States to establish more stringent standards for PM.

In the past several years, several new epidemiologic studies have begun to strengthen the understanding of the relation between exposure to PM and mortality and morbidity. Recently, HEI's National Morbidity, Mortality, and Air Pollution Study (HEI, 2000a) of the 90 largest cities in the United States, and preliminary results from the APHEA-II⁽⁴⁾ study of over 30 European cities, have found a generally consistent effect of PM and mortality, when common methods are applied, and after the effects of other pollutants are considered. The Reanalysis of the Harvard Six Cities and American Cancer Society Studies (HEI 2000b) has also reported on extensive additional analysis of these two studies that have been the basis of most U.S. and European efforts to estimate the population health effects of PM, and have generally confirmed the results, although the reanalysis did in several important ways extend and challenge our understanding. At the same time, although there has been progress in research to better understand the biological mechanism that might be causing these effects at relatively low exposure levels, there is not today an agreed-upon plausible biological mechanism for the effects.

Components and Characteristics of the PM Mixture have been identified as potentially being most responsible for mortality and other risks. Diesel exhaust particulate matter has been cited as a probable human carcinogen by several national and international agencies (including the International Agency for Research on Cancer and the U.S. Environmental Protection Agency) because of findings of lung cancer in exposed workers, although there are limits to our ability to estimate a precise risk (HEI, 1999). Hypotheses have also been put forward suggesting that ultrafine particles (less than 0.1 microns), particles containing metals (e.g. iron), and other types of particles may be the most toxic components of the mixture. To date these studies have not identified one component or characteristic that is significantly more toxic than others.(EPA 1999)

Air Toxics have a variety of characteristics and effects. Most of those emitted from motor vehicles are animal carcinogens. Benzene is a known human carcinogen. Butadiene, for which vehicles are the dominant ambient source, was recently designated as a probable human carcinogen by the International Agency for Research on Cancer, and a known human carcinogen by the U.S. National Institutes of Health. Several aldehydes (including formaldehyde and acetaldehyde) have also been designated as probable human carcinogens. In addition, several of the mobile source air toxics, especially the aldehydes, have exhibited evidence of acute respiratory effects. Recently, the U.S. Environmental Protection Agency identified a total of 21 air toxics emitted from motor vehicle exhaust (U.S. EPA 2000c)

Trends and the Future

Given the health effects of vehicle emissions, action has been taken, and continues to be taken to reduce emissions from both gasoline and diesel vehicles. The U.S. EPA took action in 1999 to further improve fuel formulation and reduce emissions of light duty vehicles, and in 2001 to promulgate stringent new fuel and emissions standards for heavy-duty vehicles. The EU is on a similar path, which is expected to substantially reduce emissions over the coming 20 years (see Figure 2). In addition, the requirements for a substantial reduction in diesel particulate

matter emissions is expected to substantially reduce cancer risk from diesel as well (IFEU, 1999). At the same time, continued growth in travel is expected to offset a portion of these reductions. As a result, continued attention to reducing emissions is likely in the future. This will come in three ways:

S continued tightening of fuel and emission standards for petrol and diesel vehicles (in 2000, the U.S. EPA tightened fuel and emission standards for both light duty and heavy duty vehicles, and in 2001 the EU is expected to tighten standards for sulfur levels in fuel)

S the introduction of new technologies: natural gas vehicles, electric and electric hybrid vehicles, and fuel cell vehicles are all in development or beginning to appear on the market. While these have certain air quality advantages, they may also raise new health questions (e.g. the use of methanol to power fuel cells), and will need to be introduced with appropriate care.

S policies to discourage growth in personal auto use - this is potentially the most important future direction, and at the same time the most challenging. Future land use and transportation policy can significantly affect travel behavior, but the ability to implement effective measures may be limited as the general public is increasingly used to and reliant upon the flexibility of the private automobile (Greenbaum, 1995).

In conclusion, the emissions of a variety of pollutants from vehicles account for, in general, approximately 25% to 40% of the ambient levels of air pollution (and in some cases more, depending on the pollutant and location). These pollutants have been demonstrated to have a measurable negative effect on the public health. As a result the long-term trend has been toward reducing emissions from motor vehicles, and that trend is likely to continue in the future. However, continued growth in vehicle travel is likely to offset at least a portion of the expected reductions, suggesting continued efforts to reduce the emissions and other impacts on public health.

References

Department of the Environment, Transport, and Regions Source Apportionment of Airborne Particulate Matter in the United Kingdom, Report of the Airborne Particles Expert Group, London, January 1999

Environmental Protection Agency National Air Toxics Program: The Integrated Urban Strategy U.S. Federal Register, Vol.64, No. 137, Washington, D.C. July 19, 1999a

Environmental Protection Agency, Air Quality Criteria for Particulate Matter, External review Draft, Office of Research and Development, Washington, D.C., October, 1999b

Environmental Protection Agency National Air Quality and Emissions Trends Report, 1998, EPA 454/R-00-003, Research Triangle Park, North Carolina, March 2000a

Environmental Protection Agency, Air Quality Criteria for Carbon Monoxide, Office of Research and Development, Washington, D.C., June 2000b

Environmental Protection Agency, Draft Mobile Source Air Toxics Study, Office of Transportation and Air Quality, Washington ,D.C July 2000c

Expert Panel on Air Quality Standards Ozone HMSO Publications Centre, London, 1997

Greenbaum, DS, Shaping Transport and health policy: a case study in the Boston, Metropolitan Areas, Massachusetts, USA, in Health at the Crossroads: Transport Policy and Urban Health, T Fletcher and AJ McMichael, eds., Wiley 1997

Health Effects Institute, Diesel Emissions and Lung cancer: Epidemiology and Quantitative Risk Assessment, A Special report of the Institute=s Diesel Epidemiology Expert Panel, Cambridge, Massachusetts, June 1999

Health Effects Institute, Research Report 65, Part XI: Consequences of Prolonged Inhalation of Ozone on F344/N Rats; Integrative Summary, Cambridge, Massachusetts, April 1995

Health Effects Institute, Strategic Plan for the Health Effects of Air Pollution 2000 - 2005, Cambridge, Massachusetts, 2000

Health Effects Institute, Research Report 94, Part II, The National Morbidity, Mortality, and Air Pollution Study, Cambridge, Massachusetts 2000a

Health Effects Institute, Reanalysis of the Harvard Six Cities and American Cancer Society Studies, A Special Report of the Institute's Particle Epidemiology Reanalysis Project, Cambridge. Massachusetts 2000b

Institute fur Energie- und Umweltforschung, Risk Assessment of Diesel and Spark Ignition Engines Emissions, Heidelberg, December, 1999

1. ¹While this is in general true, there is one instance - the case of ozone - where urban levels are generally lower than those found outside cities, the result of Ascavenging@ of the ambient ozone by high levels of ambient nitrogen oxides.

2. ² The Health Effects Institute is a not-for-profit research institute funded jointly and equally by environmental regulatory agencies and the worldwide motor vehicle and fuels industry. Established in 1980, and overseen by an independent Board of Directors, HEI provides high-quality, impartial, and relevant science for public and private decision-makers on the health effects of air pollution from motor vehicles and other sources in the environment. All of its research is selected competitively and overseen by a distinguished Research Committee of leading US and European experts. Comprehensive results of its work are reviewed intensively by an independent Review Committee which has had no part in designing or overseeing the research. Although funded initially to inform regulatory decision making in the United States, HEI has increasingly been called upon and funded by public and private officials in Europe to address key air pollution and health issues facing the European Union and its member countries. Full details about HEI and its publications can be found at www.healtheffects.org.

3. ³While this is in general true, there is one instance - the case of ozone - where urban levels are generally lower than those found outside cities, the result of Ascavenging@ of the ambient ozone by high levels of ambient nitrogen oxides.

4.

⁴ Air Pollution and Health, A European Assessment