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CLEAN AIR AND TRANSPORTATION:
THE FACTS MAY SURPRISE YOU
by Michael Koontz
 The
week of May 24-30 was Clean Air Week. All across the nation, people were
encouraged to make choices that would contribute to cleaner air. Transportation
choices are an element of this decision-making process, but the balance
between the roles of technology and trip-making behavior is being questioned.
While many areas continue to place great emphasis on the travel choice
in the quest for cleaner air, the benefits and the track record of technological
solutions are coming more into focus.
Faced with the full gamut of lingering air quality challenges,
Congress enacted the Clean Air Act Amendments (CAAA) of 1990. These amendments
confront many of the same environmental issues that prompted the original
act in 1970 and the amendments of 1977, and they continue to look toward
transportation to reduce air pollution.
Along with the familiar image of billowing smokestacks
and sprawling industrial agglomerations, automobiles and trucks have become
symbols of air pollution. Whether this is a rightful role, and whether
the onus for cleanup should be on the transportation community is now
at the forefront of the clean air debate. Regardless of where future mitigation
efforts are based, the transportation sector — and especially the automobile
industry — has done its part in the quest for better air quality.
Background — CAAA of 1990
Despite the full force of the original act and its 1977 amendments, more
than 175 areas of the United States were classified in 1990 as "air quality
nonattainment areas" — parts of the country failing to meet at least one
air quality standard.1 If you were a resident of any major metropolitan
area, you were probably breathing air that did not meet the National Ambient
Air Quality Standards (NAAQS) that the Environmental Protection Agency
(EPA) establishes for six principal air pollutants. The 1990 CAAA expanded
the existing regulatory procedures and set forth a matrix of deadlines
attached to each of these nonattainment areas. State implementation plans
(SIPs) addressing measures and milestones are mandatory under the 1990
CAAA.
Not only are the many milestones and requirements challenging, but the
sheer level of data management and record-keeping has been daunting. Each
state is required to develop an emissions budget, an accounting mechanism
creating a progressive track toward attainment of the standards. This
budget can evolve into an elaborate strategy involving tradeoffs among
point, area, and mobile sources of emissions. Prior to settlement on a
budget for the nonattainment area, the transportation community must complete
a theoretical analysis that contrasts emissions from "build" and "no-build"
scenarios, as state and regional planning organizations attempt to reach
"conformity" of their transportation plans and programs with SIPs. The
bottom line? Transportation must contribute to lower emissions — at least
until the area's budget is approved.
Air Quality Trends — A Report Card
Many of the nonattainment areas designated in 1990 have achieved their
air quality goals and have been dropped from the rolls of nonattainment
areas. We have seen the passing of a pair of major attainment deadlines
for ozone and carbon monoxide (CO) levels, and approximately 70 areas,
most of which previously had excessive ozone levels, have been redesignated
as attainment areas.
EPA's National Air Quality and Emissions Trends Report,
1996 indicates that CO levels were down 37 percent from 1987 to 1996.
In addition, during the same period, the average number of monitored exceedances
of the CO standard fell a staggering 92 percent nationally. Ozone levels
are down as well, according to the EPA's annual report published in January
1998. The average concentrations for 532 long-term air quality monitors
were 15 percent lower in 1996 than in 1987. The number of times that the
ozone standard of 0.12 ppm (a simple ratio of parts of ozone per million
parts of generic air) was exceeded was also down, falling 73 percent over
the same period.2
Gross emissions levels have also dropped for pollutants
from mobile sources. These levels are based on estimates of total tonnage
of the pollutants released from combined mobile sources. Based on the
1987 to 1996 time frame, both CO emissions and hydrocarbons fell 18 percent.
Even the persistent problem of particulate matter — airborne pollutants
that irritate the respiratory system — has been lessened; from 1988 to
1996, particulate matter was reduced by 12 percent. Interestingly, lead
pollution in the air has been checked substantially, dropping 75 percent
between 1987 and 1996, due to the removal of lead from gasoline.
Transportation as a Contributor
Since the passage of the Clean Air Act in 1970, aggregate emissions have
declined for virtually every pollutant that EPA monitors. Within these
overall reductions, most analyses point to steadily declining pollution,
including hydrocarbons and nitrogen oxides, from highway mobile sources.
Reducing hydrocarbons and nitrogen oxides is important because they are
precursors of ozone. A precursor is a pollutant that contributes to the
formation of other pollutants.
For hydrocarbons, 36 percent of total emissions were attributed to automobiles
in 1970. That figure now rests at approximately 25 percent with a further
decline expected through 2005.
Similarly, in 1970, about 20 percent of nitrogen oxides
emissions were generated by automobiles. Today, only 12 percent is attributed
to automobiles, and a further decline to 11 percent is projected for 2005.
These improvements are partially offset by a slowly growing
share of emissions from stationary sources and by an erratic, but expanding,
share from off-road sources, such as construction and farm equipment.3
The greatest boon to the decline in mobile-source emissions
has been the gradual ratcheting of vehicle-emission standards — lowered
targets that have been met consistently by the automobile industry. Prior
to the implementation of engine-emission controls, light-duty vehicles
were spewing forth levels of emissions that were manifold higher than
today's improved levels. For each mile driven, a typical mid-1960s passenger
vehicle emitted 11 grams of hydrocarbons, four grams of nitrogen oxides,
and a staggering 80 grams of CO.
With the advent of vehicle-emission standards, tailpipe-exhaust readings
plummeted. By 1972 — two years after the Clean Air Act — hydrocarbon-emission
standards were set at 3.4 grams per mile (gpm), and the CO standard was
39 gpm. After nine years and the implementation of the 1977 CAAA, the
standards were 0.41 gpm for hydrocarbons, 3.4 gpm for CO, and 1 gpm for
nitrogen oxides.
Passenger-vehicle standards remained constant for most
of the 1980s. With the 1990 CAAA, the standard for nitrogen oxides was
established for model year 1994 vehicles at 0.4 gpm, down from 1 gpm between
1987 and 1993. In addition, a more stringent standard for particulates
was implemented, dropping from 0.6 gpm in 1982 down to 0.08 gpm, also
effective with model year 1994 vehicles. Effective in 1996, hydrocarbons
dropped even further, down to a level of 0.25 gpm.4,5
Although standards for light-duty trucks have not matched
the aggressive pace set for cars, the plunge in passenger-vehicle-emission
standards illustrates the progress that can be linked directly to engine
technology. While the specter of ever-growing vehicle-miles traveled is
disconcerting, gains in emission-control technology have more than offset
this trend.
Other technologies and programs have entered the contemporary
battle for cleaner air. Straddling the technological and programmatic
approaches, reformulated gasoline (RFG), oxygenated gasoline, and inspection
and maintenance (I&M) programs have been successful in addressing both
CO and ozone. All three programs are mandated by the 1990 CAAA in specified
areas. In addition, these programs have been applied further as other
areas see the benefits of "opting-in" to these strategies.
None of these technology-based strategies is expected to
deliver the "knockout punch" to transportation-related air pollution.
However, their value as part of an integrated strategy has been well-documented.
Research conducted by the Volpe National Transportation Systems Center,
for example, indicated that enhanced I&M, potentially, would account for
nearly 15 percent of mobile-source-emission reductions. The study also
found that implementation of an RFG program reduces average mobile-source
emissions by more than 10 percent.6
Disappointments and Roadblocks — More $$$ May Not Be
the Answer
As advances in transportation technology have held emissions in check,
other strategies associated with transportation have found little success
despite very high costs. While EPA's transportation conformity process
has been less than embraced by state and regional planners, it has been
instrumental in isolating the minimal air quality benefits ascribed to
the traditional transportation control measures (TCMs) that form most
capital improvement programs. A 1993 survey of transportation plans in
the San Francisco Bay area highlighted the air quality benefits of an
$11 billion investment program largely devoted to transit system and high-occupancy-vehicle
lane construction. Using the required build and no-build assessments,
the study revealed a reduction in hydrocarbons of less than 1 percent
over the analysis period with a similar result for CO.7
A 1994 assessment of the costs and effectiveness of transportation control
measures projected small fiscal and emission-reduction efficiencies across
the TCM spectrum. The study looked at the weak performance projected for
high-capital TCMs in hydrocarbon-reduction effectiveness. This appears
to be a typical track record for the country, as models in most areas
attribute a decrease in pollutants of less than 2 percent to traditional
TCMs — a poor return on a huge investment.8
Performance figures for the Dallas metropolitan area shed
even more light on these inefficiencies. Officials in this rapidly growing
Texas region report that more than 90 percent of the area's required reductions
in highway-vehicle emissions were generated through technological improvements
and just under 10 percent through traffic flow improvements, such as wider
lanes. The remaining 0.3 percent were credited to behavioral measures
focusing on reduced highway travel.9
In the midst of such capital-intensive choices are several
new developments on the regulatory front that will carry substantial impacts
of their own. After several years of debate, EPA published new NAAQS for
both ozone and particulate matter in July 1997. Including both new and
revised standards, these more stringent requirements will put states in
the position of searching even further for new sources of emission reductions.
Similarly, EPA has developed a regional nitrogen-oxide-reduction strategy
that is also making its way through the federal rule-making process. Complete
with state-by-state nitrogen-oxide-reduction budgets, the regional strategy
is an effort to combat ozone transport — the downwind drift of both ozone
and nitrogen oxides — that especially hinders the attainment efforts of
northeastern states.
The Future — New Concepts and Technologies
States have accrued enormous air quality benefits from lowered vehicle-emission
standards and more modest, but nevertheless important, gains from developments
such as RFG and I&M programs. The common denominator among these successes
has been technology, and it is in this direction that future efforts toward
attainment will likely reap the greatest benefit.
Low-emission, zero-emission, and electric vehicles — also
known as LEVs, ZEVs, and EVs, respectively — are also expected to have
an effect on future regional emissions and the push toward attainment.
California has a ZEV-sales mandate for model year 2003 as part of its
state strategy toward clean-air attainment. Similarly, the Northeast's
Ozone Transport Commission has reached an agreement with the automobile
industry on a compromise plan that will introduce a "national LEV" to
every state except California, Maine, New Jersey, New York, and Vermont.
EPA has declared that the national LEV program is underway, and cleaner
cars are slated to be available in the Northeast for model year 1999.10
Other regulatory developments may help bring transportation
into an even more positive light. New performance standards have been
promulgated for heavy-duty diesel trucks and locomotives. The standards
for diesel trucks, effective in 2004, are expected to yield a 15-percent
drop in overall truck-fleet nitrogen oxides by 2010 and a 40-percent reduction
by 2020. For railroad locomotives, the reduction in nitrogen oxides as
a result of the new performance standards is projected to be about 8 percent
by 2020.
Looking further into the next century, many automobile
industry officials are convinced that the electric drive train will be
the vehicle platform of the future. Consequently, many new applications
of the EV are making their way through the automotive labs, including
a number of "hybrid" vehicles that use combinations of different technologies.
Two of the more promising configurations are the gasoline-electric and
diesel-electric hybrids that use smaller fuel-based engines running at
constant — and efficient — speeds to generate electricity for the vehicle's
battery pack. Even further beyond the horizon, the hydrogen fuel cell
is also being projected as a viable, almost pollution-free, power platform.
Common sense also plays an important role in the reduction
of air pollution. Many states and metropolitan organizations have engaged
in widespread marketing campaigns to educate and warn the public of impending
air quality events or episodes. Referred to as "episodic measures," these
market blitzes are being used to encourage the public to refrain from
participating in polluting activities, such as lawn mowing or vehicle
refueling, during bad air days. Maryland and Oklahoma initiated programs
to forecast the bad air days.
Outlook
In many areas, especially in America's expanding metropolitan regions,
improving air quality remains a difficult challenge. There have been few
sources of consistent improvement in air quality over the quarter-century
under the Clean Air Act. An unmistakable success story, however, has been
the contribution of the automakers in their quest to keep pace with tightening
engine-emission standards. American motorists are clearly driving more
miles each year, and they are adding these extra miles to vehicles that
they're keeping longer than ever.11 Despite these trends, pollution from
on-road mobile sources has plummeted since the implementation of tailpipe
standards. Indeed, the CO problem has been virtually wiped out due largely
to engine technology.
More than 119 million Americans still live in air quality
nonattainment areas. While the recent past has been marked with success,
future reductions from on-road mobile sources will be more labored.12
Reductions have become more difficult and much more expensive to achieve
as standards have been made more stringent. The dwindling benefits of
complete fleet turnover, coupled with the steady growth in vehicle-miles
traveled, represent clear challenges for technology.
A "silver bullet" may remain elusive, but in its place,
a host of contributing technologies and measures may drive attainment
efforts. Positive roles can be played by the greater use of viable alternative
fuels, publicly supported I&M programs, and the development of the next
generation of alternative vehicles. In the three decades of vehicle-emission
standards, the purveyors of automobile technology were leaders in the
push for air quality attainment through the reduction of pollution from
on-road mobile sources. In the past, motor vehicles deserved their reputation
as a principal cause of the country's air pollution; however, as a result
of innovation and hard work, the industry deserves a new reputation as
the leader in the search for solutions.
References 1. Our Nation's Highways: Selected
Facts and Figures, Office of Highway Information Management, Federal
Highway Administration, Washington, D.C., May 1995.
2. National Air Quality and Emissions Trends Report, 1996, Office
of Air and Radiation, U.S. Environmental Protection Agency, January 1998.
3. Clearing the Air: A Report on Emission Trends in Selected Cities,
Energy and Environmental Analysis Inc. (prepared for the American Automobile
Association), September 1994.
4. Clean Air Act as Amended August 1977, 95th U.S. Congress, U.S.
Government Printing Office, Washington, D.C., November 1977.
5. Clean Air Act Amendments of 1990, 101st U.S. Congress, U.S.
Government Printing Office, Washington, D.C., November 1990.
6. Technical Report on Clean Air Act Programs, Effectiveness of Emission
Control Measures, Volpe National Transportation Systems Center, U.S.
Department of Transportation, November 1994.
7. Hank Dittmar. "Beyond Conformity: Transportation, Air Quality, and
Community Values," a presentation in Rapid City, S.D., October 1992.
8. Costs and Effectiveness of Transportation Control Measures (TCMs):
A Review and Analysis of the Literature, Apogee Research Inc. (prepared
for the National Association of Regional Councils), January 1994.
9. Frank R. Moretti. Clean Air and Improved Mobility: Meeting the Challenge,
The Road Information Program, Washington, D.C., July 1997.
10. "Air Quality Officials, Automakers Differ on 49-State LEV Costs,"
Inside EPA's Clean Air Report (newsletter), October 1995.
11. Alan E. Pisarski. "New Perspectives in Commuting," prepared for the
Office of Highway Information Management, Federal Highway Administration,
Washington, D.C., July 1992. 12. "House Republicans Question EPA's Push
to Revise Ozone Standard," Inside EPA's Clean Air Report (newsletter),
November 1995.
Michael Koontz is a transportation planner in FHWA's
Office of Environment and Planning. He has worked in the Environmental
Analysis Division since 1994, coming from the FHWA's Maryland Division
Office. Koontz joined FHWA in 1992. Prior to then, he worked for the Department
of Defense as a transportation systems analyst and as a regional geographer,
specializing in logistics and intermodal developments in the Middle East
and North Africa. Before government service, he worked as a business location
planner and as a land-use consultant in the private sector. He has a bachelor's
degree in geography and environmental planning, and he earned a master's
degree in transportation geography from Towson State University, Baltimore.
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