Briefing Report to Congressional

Committees

United States General Accounting Office

GAO

May 2001 AIR POLLUTION

Air Quality and

Respiratory Problems

in and Near the Great

Smoky Mountains

GAO-01-658
Page i GAO-01-658 Air Pollution

Letter 1

Briefing Section I Overview 10

Briefing Section II Visibility 12

Briefing Section III Ozone 18

Briefing Section IV Respiratory Illnesses 24

Briefing Section V TVA’s Emissions 34

Appendix I Comments From the Department of the Interior 40

Appendix II Comments From the Environmental Protection

Agency 41

Appendix III Comments From the Tennessee Valley Authority 43

Contents
Page 1 GAO-01-658 Air Pollution

May 25, 2001

The Honorable Charles H. Taylor

Chairman

The Honorable James P. Moran

Ranking Minority Member

Subcommittee on Legislative

Committee on Appropriations

House of Representatives

The Honorable Robert F. Bennett

Chairman

The Honorable Richard J. Durbin

Ranking Member

Subcommittee on Legislative Branch

Committee on Appropriations

United States Senate

Although air quality has generally been improving throughout much of the

United States in the past 20 years, there is growing concern about

visibility, air quality, and certain respiratory illnesses in and near Great

Smoky Mountains National Park, which straddles the border between

North Carolina and Tennessee. In light of these concerns about the park

and adjacent areas, we were directed to analyze recent trends in and

contributing factors to (1) visibility impairments, (2) ground-level ozone,1

and (3) respiratory illnesses. In addition, we were directed to examine the

Tennessee Valley Authority’s (TVA) plans to reduce its emissions of

regulated pollutants from generating electricity. We generally focused our

review on the period from 1990 to 1999 or 2000, depending on data

availability. (See H. Rept. 106-1033, Conference Report to Accompany H.R.

4577, Making Omnibus Consolidated and Emergency Supplemental

Appropriations for Fiscal Year 2001.)

The results of our work are summarized in this letter. Briefing Sections I

through V contain the charts that we used to brief Chairman Taylor and his

staff on March 1 and 22, 2001, along with explanatory notes.

 1

Ozone is a colorless gas that occurs both in the earth’s upper atmosphere and at ground

level. In this report, we use the term ozone to refer to ground-level ozone.

United States General Accounting Office

Washington, DC 20548
Page 2 GAO-01-658 Air Pollution

Reduced visibility, high ozone levels, and respiratory illnesses in and near

Great Smoky Mountains National Park are continuing concerns. Visibility

remained poor throughout the 1990s. The number of days when ozone

levels exceeded a health-based standard generally rose during the decade

but fell in 2000. Visibility impairment and ozone are largely attributable to

three types of emissions.

• Sulfur dioxide, which is generated primarily from coal-fired power plants

north and west of the park, can be transformed into sulfate particles,

which are the main contributor to reduced visibility.

• Nitrogen oxides, which are generated largely from motor vehicles, as well

as coal-fired power plants, participate in ozone formation.

• Volatile organic compounds, which result from both natural sources (such

as isoprene from trees) and human actions (including a wide range of

compounds resulting from such activities as the incomplete combustion of

gasoline), also participate in ozone formation.

The sulfate particles and ozone gas formed from these emissions are

associated with respiratory illnesses. Relative to the entire states of North

Carolina and Tennessee, the counties that border the park generally have

slightly higher death rates from two types of respiratory illness, even

though they have substantially lower death rates from all causes. Research

is continuing on why and how air pollution leads to adverse health effects.

In response to federal laws and other factors, the Tennessee Valley

Authority is making substantial environment-related investments and

expects to reduce its annual emissions of sulfur dioxide by 36 percent and

its “ozone-season” (primarily summer time) emissions of nitrogen oxides

by 68 percent between 1999 and 2005.

Great Smoky Mountains National Park encompasses 800 square miles in

North Carolina and Tennessee. Designated a national park in 1934, it is 95

percent forested and is renowned for the diversity of its plant and animal

resources and the beauty of its ancient mountains. Elevations in the park

range from 800 feet to 6,643 feet.

Areas adjacent to the park are growing in population and economic

activity. For example, between 1990 and 2000, while the U.S. population

grew 13 percent, the population of North Carolina and Tennessee grew

21 percent and 17 percent, respectively, and the population grew

18 percent in Buncombe County, the most populous county in western

North Carolina. Recreational visits to the park increased from 8.2 million

Results in Brief

Background
Page 3 GAO-01-658 Air Pollution

in 1990 to 10.2 million in 2000, and non-recreational visits to the Park

increased from 9.4 million to 10.9 million during the same period.

The burning of coal, gasoline, and other fossil fuels—by electric utilities,

motor vehicles, manufacturing facilities, and other sources—generates

sulfur dioxide and nitrogen oxide gases. When emitted into the air, these

gases, and the substances, into which they can be transformed, may be

transported hundreds of miles away. In the atmosphere, these gases may

be transformed into tiny particles or may react with other chemicals.

Visibility is impaired when light encounters these tiny airborne particles

and is absorbed or scattered before reaching the observer. Humidity

magnifies the problem because the particles may attract water and grow in

size, thereby scattering more light. In addition to reducing visibility, these

tiny particles, which can be inhaled deeply into the lungs, have been

consistently associated in epidemiological studies with hospital

admissions and premature deaths.

Ozone is not emitted; it forms when nitrogen oxides react with volatile

organic compounds in the presence of sunlight. Repeated exposure to

ozone may permanently damage lungs or trigger symptoms, such as chest

pains or coughing. It may also interfere with plants’ ability to produce and

store food, making them more susceptible to pathogens, pests, and other

pollutants. (By contrast, in the upper atmosphere, ozone forms a

protective layer that shields the earth from harmful ultraviolet rays.)

The Clean Air Act2

 requires the Environmental Protection Agency (EPA),

in concert with state and local air pollution agencies, to regulate mobile

and stationary source emissions of certain air pollutants. In addition, for

pollutants it determines to be harmful to human health, EPA is responsible

for setting standards for concentrations of those pollutants in the air that

people breathe. It has designated six such principal pollutants, including

sulfur dioxide, nitrogen dioxide, particulate matter, and ozone. Finally,

certain provisions of the act specifically address visibility impairments.

Although the 1977 amendments to the Clean Air Act established tougher

requirements for new power plants and certain other facilities, existing

facilities—including those operated by TVA and many other electric

utilities—were exempted from these requirements, so long as they did not

 2

It was enacted in its present statutory format in 1970 and has been amended since then,

most recently in 1990.
Page 4 GAO-01-658 Air Pollution

make physical changes to the plants that resulted in increased emissions.

EPA alleged in 1999 that TVA and several privately owned utilities had

violated the Clean Air Act provisions by making physical changes to their

units that had resulted in emissions increases. EPA’s lawsuit against TVA

is pending.

Despite the progress over the past 20 years in reducing the emissions of

most principal pollutants and improving air quality, ozone concentrations

in many counties in the United States exceed national standards, and

visibility in many otherwise pristine areas remains a problem. Over the

same time period, the prevalence of asthma—the most common chronic

disease of children in the United States and other developed countries—

has increased by more than half.

Visibility in Great Smoky Mountains National Park remained poor

throughout the 1990s. On the worst days (those ranked in the bottom onefifth of all days in terms of visibility—usually hot and humid summer

days), visibility ranged between 12 and 15 miles from 1989 through 1999,

according to the latest available data from the National Park Service. On

average days (the middle one-fifth of all days), visibility stayed at about 27

miles during the decade and, on the best days (those ranked in the top

one-fifth of all days), it stayed at about 51 miles.

Reduced visibility is primarily caused by airborne particles that either

scatter or absorb light. In the eastern states generally, and in the park

specifically, during the summer, these particles are predominantly fine

sulfate particles formed from sulfur dioxide gas, a product of burning coal

and other fossil fuels. The electric utility sector accounted for 67 percent

of the nation’s sulfur dioxide emissions in 1999 (latest available data); the

transportation sector, 7 percent; and other sources, the remaining 26

percent.

Because sulfur dioxide gas and the sulfate particles, into which it can be

transformed, can travel hundreds of miles on wind currents, the particles

that degrade visibility in the park may originate from emissions released

over a large area. According to a recent National Park Service analysis of

the air masses that reached the park on low-visibility days (that is, days

with high levels of particulates), the majority started, or spent

considerable time, over the industrial Midwest, which allowed them to

accumulate substantial quantities of sulfur dioxide. Air masses arrived

from the west on a lesser, but still significant, portion of the low-visibility

days, while few air masses arrived from the east and south on such days.

Visibility
Page 5 GAO-01-658 Air Pollution

In 1994, the year before the provisions of the Clean Air Act Amendments of

1990 limiting sulfur dioxide emissions took effect, the nation’s electric

utilities emitted 14.9 million tons of sulfur dioxide. In 1999, the level fell to

12.7 million tons, and it is projected to decrease to just under

9 million tons in 2010.

The number of days when ozone levels in the park exceeded a

health-based threshold set by EPA, called “exceedances,” generally

increased during the 1990s, according to data from EPA and the National

Park Service. However, the number fell sharply in 2000. It is believed that

the decline is related to the cooler summer temperatures in 2000.

Because sunlight is necessary to the formation of ozone and heat

accelerates chemical reactions, ozone levels tend to peak in the summer

months. The two principal precursors of ozone—nitrogen oxides and

volatile organic compounds—have diverse sources. Motor vehicles and

other transportation sources produced 55.5 percent of the nation’s

nitrogen oxide emissions in 1999 (latest available data); electric utilities

produced 22.5 percent; and other sources produced the remaining 22

percent. Volatile organic compounds include isoprene, which trees

produce, and various hydrocarbons, such as those emitted when gasoline

evaporates or is burned incompletely. In North Carolina, Tennessee, and

other southeastern states, trees and other natural sources produce

relatively high levels of isoprene. Thus, there is an abundance of naturally

occurring volatile organic compounds in these areas to react with nitrogen

oxides to form ozone.

According to a recent National Park Service analysis, on high-ozone days,

most of the air masses reaching the park arrived from the north and

northwest—generally after passing through the industrial Midwest. Fewer

air masses arrived from the west and south and very few arrived from the

east.

The Clean Air Act Amendments of 1990 are expected to reduce national

nitrogen oxide emissions by 2 million tons a year by 2010, relative to the

level without these provisions. Other EPA policy initiatives are intended to

make further cuts in emissions.

Ozone
Page 6 GAO-01-658 Air Pollution

Throughout the 1990s, death rates from two respiratory illnesses—

(1) chronic lung disease3

 and (2) pneumonia/influenza—in North Carolina

and Tennessee were consistently higher than the comparable national

rates. Moreover, death rates from these illnesses in the North Carolina and

Tennessee counties adjacent to the park were generally higher than the

comparable rates for these states as a whole throughout the 1990s, even

though these counties had substantially lower death rates from all causes.

(These rates are age-adjusted to allow comparability between states and

over time; however they were not adjusted for other influences, such as

rates of smoking and socioeconomic levels.)

In the past 50 years, studies conducted in the United States and abroad

have consistently shown that people who breathe polluted air are more

likely to suffer adverse health effects. These effects may be reflected in

increases in breathing problems, hospital admissions, and premature

mortality from lung and heart conditions. People over the age of 65 and

those with pre-existing chronic heart and lung conditions, such as heart

disease and asthma, are more likely than others to experience adverse

health effects from exposure to air pollutants. However, scientists do not

clearly understand why and how air pollution leads to adverse health

effects, and many other factors, notably cigarette smoking, also affect the

development and severity of lung and heart diseases.

TVA’s decision on how to meet its customers’ demands for electricity is

constrained by federal environmental laws and regulations, as well as

internal policies. In recent years, TVA relied on coal to generate 62 percent

of its electricity and on nuclear power, hydropower, and other sources, in

that order, to generate the remaining 38 percent. In 2000, TVA’s peak

capacity to generate electricity was 29.5 gigawatts (a gigawatt is a million

kilowatts). TVA estimates that its peak demand for electricity will grow

about 1.7 percent each year between 2001 and 2010. To meet this level,

TVA will have to plan for an additional one-half a gigawatt increase each

year—the equivalent of building an average-sized power plant every year.

TVA can do so by purchasing power, constructing new plants, and

providing incentives to its customers to reduce their peak demand.

 3

In this report we use the term “chronic lung disease” to refer to chronic obstructive

pulmonary disease, an umbrella term that includes asthma, bronchitis, emphysema, and

other chronic lung diseases.

Respiratory Illnesses

TVA’s Plans to Reduce

Emissions
Page 7 GAO-01-658 Air Pollution

Although TVA’s coal consumption increased from 34 million tons in 1990

to 40 million tons in 1999, its emissions of sulfur dioxide (which can be

transformed into visibility-reducing sulfate particles) declined 30 percent.

To achieve this reduction, TVA, among other actions, switched to coals

with lower sulfur contents and installed equipment called “scrubbers” to

remove sulfur dioxide from exhaust gases. TVA estimates that such

emissions will decline 36 percent between 1999 and 2005. TVA’s emissions

of nitrogen oxide (an ozone precursor) were relatively stable during the

1990s; however, it estimates that its emissions of nitrogen oxides—during

the warm-weather months when ozone levels peak—will decline

70 percent between 1999 and 2005. To achieve this reduction, TVA is,

among other actions, spending about $1 billion to install “selective

catalytic reduction” devices—which remove nitrogen oxides from the

exhaust gases—at some of its coal units.

We provided a draft of this report for review and comment to the

Departments of Agriculture, Health and Human Services, and the Interior;

EPA; and TVA. We received letters from the Department of the Interior,

EPA, and TVA, which are reprinted, along with our comments, as

appendixes I through III, respectively. Those three agencies, as well as the

Department of Agriculture and the Centers for Disease Control and

Prevention (part of the Department of Health and Human Services)

provided technical and clarifying comments, which we incorporated

where appropriate. We did not receive comments from the National

Institutes of Health (another part of the Department of Health and Human

Services).

The agencies generally agreed with the facts and analysis we presented.

The Department of the Interior said that our narrative description of

visibility conditions is accurate. However, it also said that the

methodology it uses to calculate visibility conditions is currently under

review and that some of the data we presented may be affected by this

review. EPA also told us about this review.

Similarly, EPA provided additional data on changes in the amount of

airborne sulfate particles, an indicator of visibility. EPA said that a 12

percent decrease in sulfate particles was measured at a site about 100

miles northeast of Great Smoky Mountains National Park between the

periods of 1990 through 1992 and 1998 through 2000. EPA did not provide

comparable data for Great Smoky Mountains National Park.

Agency Comments
Page 8 GAO-01-658 Air Pollution

EPA noted the overall appropriateness of how we presented the current

understanding of the health risks from the pollutants that we examined.

EPA and TVA commented that our location-specific analysis of death rates

should be viewed with caution because of the many factors that influence

the development and severity of respiratory illness. We agree.

To analyze trends in visibility and ozone, we interviewed officials from,

and reviewed studies and other documents prepared by, the Department

of the Interior’s National Park Service, the Department of Agriculture’s

Forest Service, EPA, and TVA, as well as recent scientific literature. We

also interviewed representatives of, and reviewed studies and other

documents prepared by, state officials in North Carolina and Tennessee

and the Southern Appalachian Mountains Initiative—a voluntary

partnership of federal and state agencies, industry, academia,

environmental groups, and interested public participants.

To analyze trends in respiratory illnesses, we reviewed recent scientific

literature and contacted the Centers for Disease Control and Prevention, a

unit within the Department of Health and Human Services, and EPA health

researchers to ascertain the availability of data on health outcomes

associated with exposure to air pollution. We focused our analysis on

mortality data because they were available for the nation as a whole and

for the counties in North Carolina and Tennessee—the two states that

border the park. We also focused on death from all causes and on death

from pneumonia/influenza and chronic lung disease, two sets of illnesses

that many studies associate with exposure to air pollution. We obtained

national data from the Department’s National Center for Health Statistics

and state and county data from the North Carolina and Tennessee health

agencies.

To describe trends in areas near the park, we divided counties in each

state into regions used by the state agencies responsible for air quality

monitoring and selected the region in each state that borders the park. To

analyze the data for deaths from all causes and from selected respiratory

illnesses, we used the same statistical procedures and significance tests

that the National Center for Health Statistics uses to develop national

death rates. To calculate death rates for comparison between the two

states and the nation we used the 1940 standard population, the current

practice of the National Center for Health Statistics. For the comparison

between county clusters and the states, we used the 2000 standard

population, the current practice of the North Carolina State Center for

Health Statistics.

Scope and

Methodology
Page 9 GAO-01-658 Air Pollution

Although we did not independently verify the data obtained from the

federal agencies and other sources, we used the same emissions and

mortality data that federal and state agencies and other analysts generally

use. We performed our work from October 2000 through May 2001 in

accordance with generally accepted government auditing standards.

We are sending copies of this report to the Chairman and Ranking

Member, Committee on Appropriations, United States Senate; the

Chairman and Ranking Minority Member, Committee on Appropriations,

House of Representatives; the Chairman and Ranking Member, Committee

on Governmental Affairs, United States Senate; the Chairman and Ranking

Minority Member, Committee on Government Reform, House of

Representatives; Representative Zach Wamp and other interested

Members of Congress; the Honorable Ann M. Veneman, Secretary of

Agriculture; the Honorable Tommy G. Thompson, Secretary of Health and

Human Services; the Honorable Gale A. Norton, Secretary of the Interior;

the Honorable Christine Todd Whitman, Administrator, EPA; the

Honorable Skila Harris and the Honorable Glenn L. McCullough, Jr.,

Members of the Board, TVA; and other interested parties. We will also

make copies available to others upon request.

Questions about this report should be directed to me or David Marwick at

(202) 512-3841. Key contributors to this report were Gene M. Barnes,

Richard A. Frankel, and Cheryl A. Williams.

John B. Stephenson

Director, Natural Resources and Environment
Briefing Section I: Overview

Page 10 GAO-01-658 Air Pollution

Briefing Section I: Overview

Air Pollution and Respiratory Illnesses in

and Near the Great Smoky Mountains

National Park

Briefings for

Chairman Charles H. Taylor

Subcommittee on Legislative

House of Representatives

March 1 and 22, 2001
Briefing Section I: Overview

Page 11 GAO-01-658 Air Pollution

As directed by House Report 106-1033 and as discussed with Chairman

Charles H. Taylor, we focused on four issues:

• visibility, which is important to people who live near the park, visitors

from other areas who travel to enjoy the park’s vistas, and others;

• ozone, which can harm people, animals, and plants;

• respiratory illnesses, a manifestation of the harm from ozone and other

causes; and

• Tennessee Valley Authority’s (TVA) plans to reduce its emissions of sulfur

dioxide and nitrogen oxides.

To do this work we interviewed officials from, and reviewed studies and

other documents prepared by, the following five federal agencies:

• the Department of Agriculture’s Forest Service,

• the Department of Health and Human Services’ Centers for Disease

Control and Prevention and National Institutes of Health,

• the Department of the Interior’s National Park Service,

• the Environmental Protection Agency (EPA), and

• TVA.

We also collected information from North Carolina and Tennessee state

agencies, non-profit groups, and others.
Briefing Section II: Visibility

Page 12 GAO-01-658 Air Pollution

Briefing Section II: Visibility

Visibility

Source: National Park Service

Visibility in the Park on the Worst Days Remained

Poor During the 1990s
Briefing Section II: Visibility

Page 13 GAO-01-658 Air Pollution

Reduced visibility is caused by small particles in the air. In the east

generally, and in the park specifically, most of these particles are sulfates,

which are formed in the air from sulfur dioxide gas.

In analyzing visibility, we focused on the worst days, typically summer

days, because it is then that reduced visibility is the most detrimental to

enjoyment of the park. We obtained data for visibility on the worst days in

Great Smoky Mountains National Park and two others parks selected for

comparison. The other parks are Shenandoah in Virginia and Acadia in

Maine.

On the worst-visibility days (those ranked in the lowest one-fifth of all

days for each year), visibility in the park remained poor between 1989 and

1999, ranging between 12 and 15 miles, according to data from the

National Park Service. Visibility remained essentially unchanged on

average days and on the best-visibility days. Between 1989 and 1999,

visibility on the worst days in Shenandoah generally stayed at about

12 miles, while it improved in Acadia to 22 miles.
Briefing Section II: Visibility

Page 14 GAO-01-658 Air Pollution

Visibility

Source: EPA

Electric Utilities Produce Two-Thirds of National

Sulfur Dioxide Emissions
Briefing Section II: Visibility

Page 15 GAO-01-658 Air Pollution

Sulfate particles, in turn, are formed primarily from sulfur dioxide gas.

For the nation, the largest source of sulfur dioxide gas emissions in 1999

was the electric utility industry, which accounted for about 67 percent of

the total, according to EPA’s estimates. The transportation sector

accounted for 7 percent and other sources accounted for the remaining 26

percent.

The 1990 amendments to the Clean Air Act require that sulfur dioxide

emissions by electric utilities be reduced between 1995 and 2010. Electric

utility emissions of sulfur dioxide declined substantially during the

1990s—from 16.2 million tons in 1989 to 12.7 million tons in 1999.

Under these amendments, these emissions are scheduled to decline to just

under 9 million tons a year in 2010.
Briefing Section II: Visibility

Page 16 GAO-01-658 Air Pollution

Visibility

Note: Color differences denote different times at which plants must

meet requirements under the Clean Air Act Amendments of 1990

Source: EPA

Many Power Plants Are Close to the Park
Briefing Section II: Visibility

Page 17 GAO-01-658 Air Pollution

Atmospheric studies have found that sulfate produced from power plant

emissions can travel many hundreds of miles. Therefore, the visibilityreducing sulfates that reach the park can come from sources near and far.

Dozens of power plants are located in the eastern states.

National Park Service analysts recently traced the paths of the air masses

that delivered sulfate particles to the park for the 3 days before reaching

the park; they did this for both high- and low-visibility days, between May

and September in the years 1995 through 1999. They found that on highvisibility days (that is, days with low levels of particulates), the air masses

arrived from nearly all directions of the compass, although very few air

masses arrived from the northeast. The air masses had often traveled

many hundreds of miles, with some of them starting their 3-day journey as

far away as Canada, the Gulf of Mexico, or the Atlantic Ocean. Because

they traveled so quickly, they spent little time over any particular area,

including the industrial Midwest and other areas with high levels of sulfur

dioxide emissions.

Conversely, they found that on low-visibility days (that is, days with high

levels of particulates), the air masses generally had traveled shorter

distances, with most of them starting their 3-day journey just a few

hundred miles away from the park and often following more roundabout

trajectories, which kept them over particular areas for longer times. The

predominant majority of the air masses started over the industrial

Midwest, or spent considerable time there, which allowed them to

accumulate substantial quantities of sulfur dioxide. A lesser, but still

significant, portion of the air masses on these low-visibility days arrived

from the region west of the park, while few air masses arrived from the

east and south on such days.

Research continues on the sources of the air pollution that affects the

park. The authors of a 1990 study told us that they are updating their study

and hope to publish their results next year. Also, the Southern

Appalachian Mountains Initiative—a voluntary partnership of federal and

state agencies, industry, academia, environmental groups, and interested

public participants—is analyzing the issue and also hopes to publish its

results next year.
Briefing Section III: Ozone

Page 18 GAO-01-658 Air Pollution

Briefing Section III: Ozone

Ozone

Note: Data for Great Smoky Mountains National Park are for Look Rock

Source: National Park Service for Great Smoky Mountains and Shenandoah for 1999 and 2000;

otherwise, EPA

Exceedances of the Proposed Ozone Standard in the

Park Increased in the 1990s, but Fell Sharply in 2000
Briefing Section III: Ozone

Page 19 GAO-01-658 Air Pollution

Ground-level ozone is not emitted. It is produced from nitrogen oxides and

volatile organic compounds in the presence of sunlight. Heat accelerates

the chemical processes through which ground-level ozone is formed.

Pursuant to the Clean Air Act, EPA establishes public health standards for

various air pollutants. For ozone, EPA has established a threshold of

0.08 parts per million, measured over an 8-hour period. An “exceedance” is

recorded on any day when a monitor measures ozone levels that exceed

this threshold. (The state of North Carolina has adopted the federal

standard.)

We analyzed the number of exceedances during 1990 through 2000 for the

Great Smoky Mountains and Shenandoah national parks and through 1999

for Acadia National Park. (Data for Acadia for 2000 were not available at

the time of our review.).

• In the early and mid-1990s, the number of exceedances rose moderately in

the park and was generally stable for the other two locations.

• In 1997-99, the number of exceedances was much higher for the Great

Smoky Mountains and Shenandoah but remained level for Acadia.

• In 2000, the number of exceedances for the Great Smoky Mountains and

Shenandoah fell sharply to about the 1996 level.

It is believed that this decline in the number of exceedances is related to

the cooler summer temperatures in 2000.
Briefing Section III: Ozone

Page 20 GAO-01-658 Air Pollution

Source: EPA

Ozone

The Transportation Sector Produces Over Half of

National Nitrogen Oxide Emissions
Briefing Section III: Ozone

Page 21 GAO-01-658 Air Pollution

In 1999, the transportation sector emitted 55.5 percent of nitrogen oxides

nationwide, according to EPA’s estimates. This includes cars and trucks

(called on-road vehicles), as well as farm equipment and other engines

(called non-road sources). Electric utilities accounted for 22.5 percent and

other sources, the remaining 22 percent.

The transportation sector’s emissions of nitrogen oxides increased from

12.2 million tons in 1989 to 14.1 million tons in 1999—a rise of 16 percent.

This increase is less than the 28-percent increase during that same period

in the number of miles traveled by cars, trucks, and other vehicles,

according to the Federal Highway Administration.

Within the transportation sector, cars, trucks, and other on-road vehicles

emitted 8.6 million tons in 1999, according to EPA. Farm equipment, lawn

and garden equipment, and other non-road sources emitted the remaining

5.5 million tons.

National Park Service analysts recently traced the paths of the air masses

that arrived at the park on the lowest and highest ozone days from

1995 through 1999; specifically, they traced the masses for the 3 days

before they reached the park. On the low-ozone days (those ranked among

the

15 percent with the lowest concentrations during the 5-year period), the

air masses arrived from all directions, with a slight preponderance from

the south and relatively few traveling over the northeast (New England to

Pennsylvania). A substantial proportion of the air masses traveled long

distances within 3 days; many traveled from the Atlantic Ocean and Gulf of

Mexico, and a few traveled from the west (the Plains states) and the north

(Canada).

On the high-ozone days (every day when an exceedance of the 8-hour

standard was recorded in the park), the air masses traveled substantially

shorter distances within 3 days. Virtually none of the paths extended back

to the Atlantic Ocean or Gulf of Mexico. Even on land, the air masses

traveled substantially shorter distances within 3 days than on low-ozone

days, but they still traveled hundreds of miles, and a much smaller

proportion arrived from south of the park. Thus, on high-ozone days, most

air masses arrived in the park from the north and northwest—generally

the industrial Midwest—with fewer air masses arriving from the west and

south and very few arriving from the east.
Briefing Section III: Ozone

Page 22 GAO-01-658 Air Pollution

Note: Data presented for the 15 states with the largest volume of natural Volatile Organic Compounds

Source: GAO analysis of EPA data

Ozone

Southeastern States Produced Abundant Natural

Volatile Organic Compounds per Square Mile, 1997
Briefing Section III: Ozone

Page 23 GAO-01-658 Air Pollution

Volatile organic compounds, which are another ozone precursor, originate

from:

• human activities, such as various hydrocarbons that are emitted when

gasoline and other fuels evaporate or are burned incompletely, and

• natural sources, such as isoprene from trees.

In 1997, the amount of naturally emitted volatile organic compounds

(28 million tons) nationwide was greater than the amount released

through human activities (19 million tons), according to EPA.

The Southeast, because of its forests, is particularly rich in the naturally

produced compounds. Of the 15 states with the largest total amount of

these compounds, the 8 states with the greatest concentrations—pounds

per square mile of land area—are all located in the Southeast. Thus, there

is an abundance of naturally occurring volatile organic compounds in

these areas to react with whatever nitrogen oxides are produced to form

ozone. Because the formation of ozone in such a geographic area is

constrained by the available amount of nitrogen oxides (called NOx), such

an area is described as being “NOx limited.”
Briefing Section IV: Respiratory Illnesses

Page 24 GAO-01-658 Air Pollution

Briefing Section IV: Respiratory Illnesses

Respiratory Illnesses

 50 Years of Research Associates Health Problems With

Air Pollution

• Increasing evidence associates air particles and

ozone with respiratory problems.

• Small particles seem to be particularly harmful to

human health.

• Air quality is one of many factors that influence the

development and severity of disease.

• Research continues to try to better understand the

causal link.
Briefing Section IV: Respiratory Illnesses

Page 25 GAO-01-658 Air Pollution

Over the past 50 years, epidemiological and other studies both here and

abroad have consistently found that exposure to fine air particles and

ozone is associated with respiratory and other health problems.

Specifically, health effects—such as hospital admissions and premature

mortality—increase as concentrations of ozone or airborne particles

increase. These effects are seen most strongly in people with existing

heart and lung conditions. Small particles seem to be particularly harmful

to human health, in part because they can be inhaled deeply into the lungs

and may carry other pollutants on their surfaces.

A range of factors influences the development and severity of lung and

heart conditions, including exposure to allergens or pollutants, genetics,

and behavior. For example, cigarette smoking is a primary cause of

chronic lung disease, other than asthma, and lung cancer.

Epidemiological studies alone are limited in their ability to prove causality.

However, they can suggest relationships for further scientific research, as

in the case of cigarette smoking and heart disease. The exact causal link

between exposure to air pollution and adverse health effects is not

completely understood and research continues to try to learn the

mechanisms by which pollutants harm human health and which kinds of

airborne particles are the most harmful.
Briefing Section IV: Respiratory Illnesses

Page 26 GAO-01-658 Air Pollution

Respiratory Illnesses

Note: Differences in death rates are statistically significant

Source: National Center for Health Statistics, and GAO analysis of unpublished data

Death Rates for All Causes Were Higher in North

Carolina and Tennessee Than in the United States
Briefing Section IV: Respiratory Illnesses

Page 27 GAO-01-658 Air Pollution

To analyze trends in health, we used data on mortality—deaths—because

comparable state-specific and national data on other health outcomes,

such as hospitalizations, were not available. We adjusted all death rates for

age to control for differences in the age distribution of the different

populations. Age adjustment allows comparisons of rates over time and

between groups; however, the rates are not adjusted for other influences,

such as rates of smoking and socioeconomic levels.

We made three sets of comparisons for death rates from all causes and for

deaths from chronic lung disease from 1991 through 1998:

1. We compared the nation as a whole to the states of North Carolina and

Tennessee.

2. We compared the entire state of North Carolina with the 19 counties

that constitute western North Carolina, as categorized by the state’s

Department of Environment and Natural Resources.

3. We compared the entire state of Tennessee with the 16 counties in

eastern Tennessee, as categorized by the state’s Department of

Environment and Conservation.

In the first set of comparisons, we found that from 1991 through 1998

• overall death rates were consistently higher in North Carolina than in the

United States as a whole, and higher in Tennessee than in North Carolina.

• overall deaths rates declined by 8 percent for the United States as a whole

and by 5 percent for North Carolina, and essentially stayed the same for

Tennessee.
Briefing Section IV: Respiratory Illnesses

Page 28 GAO-01-658 Air Pollution

Respiratory Illnesses

Note: Differences in death rates are statistically significant

Source: National Center for Health Statistics, and GAO analysis of unpublished data

Death Rates for Chronic Lung Disease Were Higher in

North Carolina and Tennessee Than in the United States
Briefing Section IV: Respiratory Illnesses

Page 29 GAO-01-658 Air Pollution

Two sets of respiratory illnesses—chronic lung disease (a term applied to

several related conditions including asthma, chronic bronchitis, and

emphysema) and pneumonia/influenza—have consistently been associated

with exposure to ozone and airborne particles. In the United States, these

two sets of respiratory illnesses have been the fourth and sixth leading

causes of death since 1991. Each year they together account for about 9

percent of all deaths.

For chronic lung disease, we found that between 1991 and 1998

• the rates for North Carolina were usually higher than the rate for the

United States as a whole, and the rates for Tennessee were always higher

than the rates for North Carolina;

• during the time period, these rates generally increased, which is counter to

the general decline in death rates; and

• the increases in rates varied—6 percent for the United States but about

19 percent for North Carolina and 20 percent for Tennessee.

The trends for pneumonia/influenza followed similar patterns. Death rates

in North Carolina and Tennessee were higher than the national rates, and

the rates in Tennessee were usually higher than the rates in North

Carolina. Moreover, death rates increased in each state by about

10 percent, but decreased slightly for the nation.
Briefing Section IV: Respiratory Illnesses

Page 30 GAO-01-658 Air Pollution

Respiratory Illnesses

Note: Differences in death rates are statistically significant

Source: GAO analysis of unpublished North Carolina and Tennessee data

Death Rates for All Causes Were Lower in Areas

Adjacent to the Park Than in Those States as a Whole
Briefing Section IV: Respiratory Illnesses

Page 31 GAO-01-658 Air Pollution

To analyze trends in health problems within each state, we compared

age-adjusted death rates for the states of North Carolina and Tennessee

with death rates for clusters of counties that border the park. In analyzing

death rates for the entire state of North Carolina versus the 19 counties in

western North Carolina, we found that

• overall death rates were consistently higher for the state than for western

North Carolina

• during the period, death rates dropped by 3 percent for the state and

2 percent for western North Carolina.

Results for the entire state of Tennessee versus the 16 counties in eastern

Tennessee were similar, except that death rates rose slightly from 1991

through 1998. We found that

• overall death rates were consistently higher for the state than for eastern

Tennessee and

• during the period, death rates increased by 3 percent for the state and

4 percent for eastern Tennessee.

To enhance the soundness of our analysis, we compared deaths occurring

over 2-year periods, rather than single years.
Briefing Section IV: Respiratory Illnesses

Page 32 GAO-01-658 Air Pollution

Respiratory Illnesses

Note: Differences in death rates are statistically significant

Source: GAO analysis of unpublished North Carolina and Tennessee data

Death Rates for Chronic Lung Disease Increased in

North Carolina and Tennessee Between 1991 and 1998
Briefing Section IV: Respiratory Illnesses

Page 33 GAO-01-658 Air Pollution

Finally, we focused on the two respiratory illnesses—chronic lung disease

and pneumonia/influenza—in the states and county clusters. For chronic

lung disease:

• there were increases in age-adjusted mortality during this period in both

states—about 19 percent in North Carolina and about 20 percent in

Tennessee,

• the rate per 100,000 deaths increased slightly faster in western North

Carolina than in the state as whole, and

• the rate in eastern Tennessee increased more slowly than did the rate for

the entire state.

The death rates for pneumonia/influenza (not shown here) were lower

than the rates for chronic lung disease but increased in both states about

10 percent. The rate in western North Carolina increased more slowly than

did the state rate and the rate in eastern Tennessee increased somewhat

more rapidly.

Research is ongoing, in this country and abroad, to address the scientific

uncertainties of the causal links between exposure to air pollution and

harm to human health.
Briefing Section V: TVA’s Emissions

Page 34 GAO-01-658 Air Pollution

Briefing Section V: TVA’s Emissions

TVA’s Emissions

Source: TVA

TVA Relied on Coal to Generate 62 Percent

of Its Electricity, 1996-2000
Briefing Section V: TVA’s Emissions

Page 35 GAO-01-658 Air Pollution

TVA’s choices in generating power are constrained by laws, regulations,

and internal policies. For example,

• The Clean Air Act limits certain emissions from coal-fired power plants.

• The TVA Act provides that the generation of power from hydroelectric

units is a lower priority than navigation and flood control.

• An internal TVA policy limits the time period when TVA can draw down

the lakes (reservoirs) that it manages for flood control and in the process

generate hydropower.

The longer the time frame, the more TVA must and can do to comply with

laws, regulations, and policies. Because of the multiple purposes in the

TVA Act and elsewhere, and because of other laws, regulations, and

policies, TVA faces a difficult balancing act between its operating

priorities and the often conflicting or competing user needs.

To generate electricity TVA relies primarily on coal. Between 1990 and

1999 TVA’s coal consumption increased 18 percent. In the most recent 5-

year period from 1996 through2000, coal accounted for 62 percent, nuclear

power accounted for 28 percent, hydroelectric power accounted for 9

percent, and other sources accounted for the remaining 1 percent.

During that 5-year period, the amount of nuclear power increased from

35.4 to 46.9 million kilowatt-hours, and its share of the total increased

from 24 percent in 1996 to 31 percent in 2000. In the same period, the

amount of hydroelectric power fluctuated, largely because of changes in

water levels; it generally declined from 16.1 to 8.8 million kilowatt-hours,

and its share of the total declined from 11 percent in 1996 to 6 percent in

2000.
Briefing Section V: TVA’s Emissions

Page 36 GAO-01-658 Air Pollution

TVA Cut Its Sulfur Dioxide Emissions During the 1990s

and Expects to Cut More by 2005

Source: TVA

TVA’s Emissions
Briefing Section V: TVA’s Emissions

Page 37 GAO-01-658 Air Pollution

TVA’s emissions of sulfur dioxide declined 30 percent from 1989-99. It

estimates that, as a result of additional steps under way and planned for

the next decade, its sulfur dioxide emissions will decline an additional

36 percent between 1999 and 2005. (The percentage reduction reflects

TVA’s most recent estimate of 2005 emissions, which is not reflected in the

figure.)

Among the steps TVA has taken and plans to take to reduce these

emissions are:

• burning coals with lower sulfur contents at 51 of its 59 units and

• installing equipment called “scrubbers” in two units each at the

Cumberland, Paradise, and Widows Creek plants. Scrubbers can remove

more than 90 percent of the sulfur dioxide from a plant’s emissions and

are considered the best currently available technology for reducing such

emissions.
Briefing Section V: TVA’s Emissions

Page 38 GAO-01-658 Air Pollution

TVA’s Emissions

Note: The ozone season is May 1 to September 30

Source: TVA

TVA Expects to Cut Its “Ozone-Season” Emissions

of Nitrogen Oxides Sharply by 2005
Briefing Section V: TVA’s Emissions

Page 39 GAO-01-658 Air Pollution

In looking at emissions of nitrogen oxides, we focused on the 5-month

“ozone season” (May 1 through Sept. 30) when ozone levels tend to be

relatively high.

TVA’s emissions of nitrogen oxide in 1999 were about the same as in 1989.

In 1998, TVA announced plans to invest nearly $1 billion in pollutioncontrol equipment. It projects that its ozone-season nitrogen oxide

emissions will decline about 68 percent between 1999 and 2005. (The

percentage reduction reflects TVA’s most recent estimate of 2005

emissions, which is not reflected in the figure.)

The planned equipment includes selective catalytic reduction devices for

25 of its 59 coal-fired units. These devices transform nitrogen oxide

emissions into harmless nitrogen and water vapor.
Appendix I: Comments From the Department

of the Interior

Page 40 GAO-01-658 Air Pollution

Appendix I: Comments From the Department

of the Interior
Appendix II: Comments From the Environmental Protection

Agency

Page 41 GAO-01-658 Air Pollution

Appendix II: Comments From the

Environmental Protection Agency
Appendix II: Comments From the Environmental Protection

Agency

Page 42 GAO-01-658 Air Pollution
Appendix III: Comments From the Tennessee

Valley Authority

Page 43 GAO-01-658 Air Pollution

Appendix III: Comments From the Tennessee

Valley Authority

(360077)

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