Meeting the Challenge
of Cleaner Air
1
United States • Canada
Progress under the ^ U U O
Air Quality Agreement
r~.y
•
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A History of Cooperation
ultiple environmental and health problems (including acid rain, impaired visibility,
damaged ecosystems, and respiratory illness) are caused or worsened by air pollution
from mobile and stationary emission sources in Canada and the United States. Both
^nations have an interest in reducing transboundary air pollution. In 1991, the
^^Sm United States and Canada committed to reduce the impact of transboundary
f air pollution through the United States-Canada Air Quality Agreement
^ f (AQA). The AQA established a formal and flexible method of addressing
I transboundary air pollution and paved the way for cooperation on a variety of
*^J^^ air quality issues, including acid rain, ozone, and particulate matter (PM).
This brochure provides an overview of the AQA and features recent progress
made by the United States and Canada to control transboundary air pollution
under the Agreement. A more complete presentation and discussion of
this progress can be found in the 2008 Progress Report at and .
Air Quality Agreement
The 1991 Air Quality Agreement originally included two annexes. Annex 1, the Acid Rain
Annex, focuses on the commitments of both nations to reduce emissions of sulfur dioxide
(S02) and nitrogen oxides (NOX), the primary precursors of acid rain. Under Annex 2, the
Scientific and Technical Activities and Economic Research Annex, the United States and
Canada agree to coordinate their respective air pollution monitoring networks and exchange
information.
In December 2000, Annex 3, the Ozone Annex, was added to the Agreement. This Annex
commits the two nations to reducing emissions of NOX and volatile organic compounds (VOCs),
the precursor pollutants to ground-level ozone. Ground-level ozone is the major component of
smog.
In 2007 and 2008, negotiating sessions were held between the United States and Canada to
discuss a PM Annex under the AQA.
A bilateral Air Quality Committee is responsible for coordinating the overall implementation
of the AQA. Two subcommittees—Program Monitoring and Reportingand Scientific
Cooperation—meet annually with the Air Quality Committee and carry out yearly activities.
The two nations prepare a joint progress report every two years and conduct a regular five-year
review and assessment of the Agreement.
Note: American spelling is used throughout this brochure.
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The Acid Rain Challenge
Acid Rain
Acid deposition, more commonly known as acid rain, occurs when emissions of S02 and NOX from power plants,
vehicles, and other sources react in the atmosphere (with water, oxygen, and oxidants) to form various acidic
compounds. These acidic compounds then fall to earth in either a wet form (rain, snow, or fog) or a dry form (gases and
particles) and can harm aquatic and terrestrial ecosystems (particularly forests); affect human health; impair visibility;
and damage automotive finishes, buildings, bridges, monuments, and statues.
Key Commitments of the Acid Rain Annex
Both the United States and Canada have been successful in reducing S02 and NOX emissions and thus, mitigating
the impact of acid rain on each side of the border. Despite these achievements, however, further efforts are needed to
restore all damaged ecosystems to their pre-acidified conditions.
Commitments and Progress: SO, Emission Reductions
CANADA:
• In 2006, Canada's total S02 emissions were 2 million
tonnes,1 or about 38 percent below the national cap of
3.2 million tonnes (Figure 1).
• S02 reductions represent more than a 55-percent
decrease from Canada's total S02 emissions in 1980 and
a 35-percent decrease from the 1990 emission level.
• S02 emissions in the seven easternmost provinces were
1.4 million tonnes in 2005, or nearly 40 percent below
the (now expired) eastern Canada cap of 2.3 million
tonnes.
• Canada is committed to further reducing acidifying
emissions through the more recent Canada-wide Acid
Rain Strategy for Post-2000.
Figure 1. Canadian SO2 Emissions from
Acid Rain Sources, 198O-2OO6
National S02 Cap: 3.2 million tonnes
'19921 '19961
Year
'20001
'20041
'20061
UNITED STATES:
• The United States succeeded in meeting its commitment
to reduce annual S02 emissions by 10 million tons from
1980 levels by 2000.
• In 2007, emissions of S02 from the electric power sector
fell below the 2010 national emission cap of 8.95 million
tons for the first time, achieving the U.S. commitment
three years early (Figure 2).
• National S02 emissions from all sources have fallen from
nearly 26 million tons in 1980 to less than 13 million
tons in 2007 (see ).
• Most of the reductions in S02 emissions are due to
the Acid Rain Program (ARP), which requires major
reductions of S02 and NOX emissions from the electric
power sector.
1 One tonne is equal to 1.1 short tons.
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Figure 2. U.S. SO2 Emissions from Acid Rain
Program Electric Generating Units, 198O-2OO7
20-
18-17.3
16-
14-
12-
10-
8-
6-
4-
2-
I All Affected Electric Generating Units
I Phase II (2000 on) Sources
I Phase I (1995-1999) Sources
Allowances Allocated
Ii980li9851i9901i
Source: EPA, 2008
II
i
10.2 ™ 10.3 10.2
^^•gsjgsjgsjgs 95 95
.'1997'1998'l999'200o'200l'2002'20031:
Year
Commitments and Progress: NOX Emission Reductions
CANADA:
• Surpassed its NOX emission reduction target at power
plants, major combustion sources, and metal smelting
operations by 100,000 tonnes below the forecasted level
of 970,000 tonnes.
• Recently passed stringent standards for NOX emissions
from on-road and off-road sources, effective from 2004
to 2009.
UNITED STATES:
• Emissions of NOX from all NOX program-affected units
were 3 million tons, and total NOX emissions from all
sources covered by the ARP were 3.3 million tons
(Figure3).
• This level is 4.8 million tons less than the projected NOX
levels for 2000 without the ARP, or more than double the
NO emission reduction goal under the Acid Rain Annex.
Preventing Air Quality Deterioration
and Protecting Visibility
Under the Acid Rain Annex, Canada and the United States
have recognized the importance of preventing air quality
deterioration and protecting visibility from sources that could
cause significant transboundary air pollution. In October 2007,
a joint U.S.-Canada visibility workshop was held in Research
Triangle Park, North Carolina. The U.S. Environmental
Protection Agency (EPA), the U.S. Federal Land Managers,
and Canadian government representatives came together to
review the history of the U.S. visibility program and to share
information and lessons learned from joint analyses, discuss
international transport, and investigate future collaboration.
-- V
(/) °
—
'E
uj-2.
Figure 3. NOX Emission Trends for All
Acid Rain Program Units, 199O-2OO7
7-
5-
I NOX Program Affected Sources
I Title IV Sources Not Affected for NOY
1990 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Year
Source: EPA, 2008
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Acid Deposition Trends
Both nations use wet deposition (rain or snow) data to assess how the atmosphere is responding to decreasing
or increasing emissions of sulfur and nitrogen. Figures 4 and 5 show the U.S.-Canada spatial patterns of wet
sulfate and wet nitrate deposition, respectively, for 1990 and 2005. The pattern from 1990 to 2005 illustrates that
significant reductions occurred in wet sulfate deposition in both the eastern United States and much of eastern
Canada. Reductions in wet nitrate deposition have generally been more modest than for wet sulfate deposition.
Figure 4. Annual Sulfate Wet Deposition
199O 2OO5
kg/hatyr
. ' <= 5
i : 5 -10
I h°-is
i 15 - 20
I I 20 - 25
I 25-30
Figure 5. Annual Nitrate Wet Deposition
199O 2OO5
Consultation
and Notification
Concerning
Significant
Transboundary
Air Pollution
Since 1994, Canada and the United
States have regularly notified each
other concerning potential new
sources and modifications to existing
sources of transboundary air pollution
within 62 miles (100 km) of the
U.S.-Canada border. Since publication
of the 2006 United States-Canada
AQA Progress Report, Canada has
notified the United States of eight
additional sources, for a total of 52
Canadian notifications. The United
States has notified Canada of nine
additional sources, bringing the total
number of U.S. notifications to 56.
More information is available on the
government Web sites of each
country at:
Canada:
www.ec.gc.ca/cleanair-airpur/CAOL/
canus/eanus applic e.cfm
United States:
www.epa.gov/ttn/gei/uscadata.html
Source: National Atmospheric Chemistry (NAtChem) Database (www.msc-smc.ec.gc.ca/natchem/index_e.html)
and the National Atmospheric Deposition Program (NADP)
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11 .11 i I I
Making Progress on Ground-Level Ozone
Ground-Level Ozone
Ground-level ozone is a gas that forms when emissions of NOX and VOCs react with other chemicals in the air in the
presence of strong sunlight. NOX and VOCs are emitted by combustion sources (such as vehicles and power plants). VOCs
are also given off by solvents, cleaners, and paints. Ground-level ozone can cause or exacerbate respiratory illnesses and is
especially harmful to young children, the elderly, and those suffering from chronic asthma and/or bronchitis. Ground-level
ozone can affect leaves and roots of plants, especially trees, which can make them more susceptible to attack from insects
and diseases and can reduce their ability to withstand droughts, windstorms, and manmade stresses such as acid rain.
Key Commitments of the Ozone Annex
The commitments to reduce NOX and VOCs apply to a defined region in both countries known as the Pollutant Emission
Management Area (PEMA), which includes central and southern Ontario, southern Quebec, 18 U.S. states, and the District of
Columbia. The states and provinces within the PEMA are the areas where emission reductions are most critical for reducing
transboundary ozone.
CANADA:
• The Ozone Annex commits Canada to new stringent NOX and VOC emission reduction standards for vehicles, engines, and
fuels. By 2020, it is estimated that NOX and VOC emissions combined from on-road and off-road vehicles and engines in the
Canadian portion of the PEMA will be reduced by 41 and 35 percent, respectively, compared to 2005 emissions.
• With regard to stationary sources, Canada is complying with its commitment to cap NOX emissions from large fossil fuel-
fired power plants in the Ontario and Quebec portions of the PEMA at 39 kt and 5 kt, respectively, for 2007.
• Canada has taken efforts to reduce VOC emissions by developing two regulations—one on dry cleaning and another on
solvent degreasing—and using VOC emission limits for new stationary sources.
• The Canada-wide Standard (CWS) for ozone committed provincial jurisdictions to developing implementation plans
outlining the comprehensive actions being taken within each jurisdiction to achieve the standards.
UNITED STATES:
• The Ozone Annex commits the United States to
implementing the NOX transport emission reduction
program, known as the NOX SIP Call, in the PEMA states
that are subject to the rule.
• As of 2007, all affected states and the District of Columbia
chose to meet the mandatory NOX SIP Call emission
reductions primarily through participating in the NOX
Budget Trading Program (NBP), a market-based cap and
trade program.
• In the 2007 ozone season (May 1 to September 30),
sources participating in the NBP emitted 506,312 tons of
NOX (Figure 6).This is almost 5 percent below the 2007
allowable NO emission level (total state trading budget).
Figure 6. Ozone Season NOX Emissions
under the NOV Budget Trading Program
I Ozone Season NOX Emissions (thousand tons)
I Total State Trading Budget
2,000- 1,924
500-
849
• ^ 508 506™
1990
Source: EPA, 2
2000
2004
Year
2005
2006
2007
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• To help reduce emissions of NOX and VOCs from major new sources, EPA has promulgated New Source Performance
Standards (NSPS) for the 36 categories of stationary sources identified in the Ozone Annex.
• To help reduce VOC emissions, EPA has promulgated regulations to control hazardous air pollutant emissions for the 40
categories of industrial sources listed in the Ozone Annex. Additionally, EPA has promulgated national rules for the control
of VOCs in automobile repair coatings, consumer products, and architectural coatings.
• To address motor vehicle emissions, the United States committed to implementing regulations for reformulated gasoline,
controls of emissions from new and in-use highway vehicles and engines, and controls and prohibitions on diesel fuel
quality. EPA has applied engine standards for the five nonroad engine categories identified in the Ozone Annex.
Ambient Levels of Ozone
Under the Ozone Annex, the United States and Canada are required to report on the amount of ozone, NOX, and VOCs in
the air we breathe (i.e., ambient concentrations) from all relevant monitors within 500 km of the border. Both countries
have extensive networks to monitor ground-level ozone and its precursors, and both governments prepare routine reports
summarizing measurement levels and trends. The latest reported data from both countries are for 2006.
Figure 7 illustrates that higher levels of ozone occurred in the Great Lakes and Ohio Valley regions, as well as downwind of
urban areas.
Figure 7. Ozone Concentrations along the Canada-U.S. Border
(Three-Year Average of the Fourth Highest Daily Maximum 8-Hour Average),
2004-2006
4 I
Note: Data contoured are the 2004-2006 averages of annual fourth highest daily values, where the daily value is the highest running 8-hour average for the day. Sites used
had at least 75 percent of possible daily values for the period.
Source: Environment Canada National Air Pollution Surveillance (NAPS) Network Database, 2008 (www.etc-cte.ec.gc.ca/naps/
index_e.html); EPA Aerometric Information Retrieval System (AIRS) Database (www.epa.gov/air/data/index.html)
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Ambient Concentrations of Ozone, NOX, and VOCs
Figure 8 illustrates that ozone levels within the PEMA have decreased over time with a notable decline in ozone levels
since 2002. Figures 9 and 10 depict the average ozone season levels of ozone precursors NOX and VOCs in the eastern
United States and Canada. Although NOX and VOC concentrations have fluctuated over recent years, these fluctuations
are most likely attributable to changes in weather conditions. Overall, the data indicate a downward trend in the
ambient levels of both NOV and VOCs.
Figure 8. Annual Average Fourth Highest
Maximum 8-Hour Ozone
Concentration for Sites within 500 km of
the Canada-U.S. Border, 1995-2006
100-
10-
United States
Canada
°~l I I I I I I I I I I I
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Source: EPA and Environment Canada. 2008
Figure 9. Average Ozone Season 1-Hour
NOX Concentration for Sites within 500
km of the Canada-U.S. Border,
1995-2006
5-
1 Canada
' United States
J~l I I I I I I I I I I I
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Source: EPA and Environment Canada. 2008
Figure 10. Average Ozone Season 24-Hour VOC Concentration
for Sites within 500 km of the Canada-U.S. Border, 1997-2006
120-
-^K— Canada
°~l I I I I I ^P^P^P I
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Source: EPA and Environment Canada. 2008
o
o
o
30-
20-
• United States |
~l I I I I I I I I I
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
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New Actions on Acid Rain, Ozone,
and Particulate Matter
CANADA
The federal government's clean air initiative, Turning the Corner: An
Action Plan to Reduce Greenhouse Gases and Air Pollution, includes a
regulatory framework for air emissions that sets out proposed mandatory
and enforceable reductions in emissions of air pollutants and greenhouse
gases from industrial sectors, as well as regulatory and other action
plans for transportation and consumer and commercial products. In
addition to delivering measurable overall health and environmental
benefits, the expected reductions in S02 and NOX emissions from
industry and transportation will lead to reductions in acid deposition and
improvements in visibility.
UNITED STATES
Due to recent research on health effects from ozone, EPA established
new, tighter primary and secondary National Ambient Air Quality
Standards (NAAQS) for ozone. In October 2006, EPA completed a
required five-year review of the PM standards, maintained the existing
annual PM25 standard, and established a more protective 24-hour
standard. EPA also retained the existing 24-hour PM10 standard but revoked the annual PM10 standard because of a lack of
evidence linking health problems to long-term exposure to coarse particle pollution.
PM Annex Negotiations
Both countries are committed to negotiating the addition of a PM Annex to the United States-Canada AQA while actively
developing and implementing emission reduction programs to reduce fine particle concentrations.
The United States and Canada have held two negotiating sessions on a PM Annex under the United States-Canada
AQA: one in November 2007 and one in May 2008. Substantial progress was made during the most recent session, and
intersessional work is continuing.
Particulate Matter
PM includes both solid particles and liquid droplets
found in the air. Many manmade and natural
sources emit PM directly or other pollutants that
react in the atmosphere to form PM. PM comes in
a range of sizes and is associated with numerous
health effects. Particles less than 10 micrometers
in diameter (PM)0)—especially those less than 2.5
micrometers in diameter (PM25)—pose the greatest
health risk because they can be inhaled and impact
both the respiratory and cardiac systems. Sulfates
(S04) and nitrates (N03) formed from S02 and NOX
are significant components of PM25. PM is also a
major contributor to regional haze, which reduces
visibility.
New England Governors (NEG) and
Eastern Canadian Premiers (ECP)
The 31st Conference of the NEG/ECP was held in
June 2007. During this meeting, the governors and
premiers established a standing committee to draft
a regional Transportation and Air Quality Action Plan.
More information on this work and other work of the
NEG/ECP can be found at .
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Cooperation on Emissions Monitoring
and Inventories
r-
Emission Trends and Inventories
Ensuring that emission inventories are publicly available
contributes to the success of both nations' emission
reduction goals and air quality management programs.
Emission inventories help identify the major sources of
pollution, track the progress of control strategies, and
provide important data for use in air quality models.
Figures 11, 12, and 13 show emission trends for total
S02, NOX, and VOCs in Canada and the United States
from 1990 to 2006.
In the United States, the major reductions in S02
emissions from 1990 to 2006 came from electric power
generation sources. For NOX, the reductions came from
on-road mobile sources and electric power generation
sources. For VOCs, the reductions were from on-road
mobile sources, waste disposal and recycling, and
chemical and allied products manufacturing and use.
In Canada, the major reductions in S02 emissions came
from base metal smelters in the industrial sector. For NOX,
the reductions were from on-road mobile sources, electric
power generation sources, and industrial sources. For
VOCs, the reductions came from electric power generation
sources, on-road mobile sources, and solvent utilization.
AIRNow Mapping
The EPA-led AIRNow program (www.airnow.gov) provides the public
with easy access to real-time air quality information. Since 2001,
the jurisdictions in the United States and Canada have collaborated
to contribute air quality data to the AIRNow program. In 2004, the
AIRNow Web site was expanded to provide information on PM and
ozone measurements on a continental scale year-round. Canadian
and U.S. efforts continue to improve air quality characterization
by combining measurements with numerical forecasts from the
operational air quality forecasting model. Each country is improving
air quality forecasting services and continuing to develop national air
quality forecast models.
Figure 1 1. U.S. and Canadian SO2
Emissions, 199O-2OO6
30
Figure 12. U.S. and Canadian NOX
Emissions, 1990-2006
25
20
Z 15-
10-
1 United States
1 Canada
25
30
i i i i i i i i i i i i i i i i r
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Figure 13. U.S. and Canadian VOC
Emissions, 1990-2006
United States
Canada
25
10-
-10
8
•*•
•*•
'n i i i i i i i i i i i i i i i r
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Source: EPA and Environment Canada. 2008
0
~i i i i i i i i i i i i i i i i r
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
0
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Research Efforts on the Effects
of Air Pollution
Health Effects
CANADA
Between 2003 and 2007, Health Canada carried out two research programs to
characterize air pollution exposure and human health issues under the Canadian portion
of the Border Air Quality Strategy, coordinated with research in the United States. The
research programs pertain to the Great Lakes Basin Airshed and the Georgia Basin-Puget
Sound International Airshed. Further information on these studies can be found at
and
, respectively.
UNITED STATES
EPA conducts human health and exposure research as part of the Clean Air Research Program. The research conducted
in this program includes studies focused on the Detroit-Windsor area, located within the PEMA. More information on these
studies can be found at and .
Aquatic Effects
In a recent study, Canadian and U.S. scientists analyzed trends in acidification of lakes and streams in eight regions of the
northeastern United States and southeastern Canada. The scientists looked at data from 1990 to 2004, which approximately
parallels the existence of the U.S.-Canada AQA.
One of the strongest trends found in this analysis was for sulfate, an acidic compound that is formed when S02 emissions
combine with water, oxygen, and oxidants in the atmosphere. After sulfate is formed in the atmosphere it can fall back to
earth and acidify surface waters such as lakes and streams, making it difficult for acid-sensitive aquatic organisms to survive.
The results of this analysis indicate that U.S. and Canadian S02 emission reductions included in the AQA commitments have
resulted in obvious, significant, and substantial declining sulfate trends in all but one of the regions examined.
Critical Loads and Exceedances
The critical load of acid deposition is defined as the maximum deposition that an ecosystem can assimilate without significant
long-term harmful effects. For environmental impacts related to acidification, deposition of both nitrogen and sulfur compounds
can contribute to a critical load exceedance.
CANADA
In the 2004 Canadian Acid Deposition Science Assessment, for the first time in North America, new and combined critical load
estimates were generated for sulfur and nitrogen acid deposition.
UNITED STATES
In the United States, the critical loads approach is not an officially accepted approach to ecosystem protection. However,
recent activities within federal and state agencies, as well as the research community, indicate that critical loads might be
emerging as a useful ecosystem protection and program assessment tool.
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For More Information
In Canada:
Air Emissions Priorities
Environment Canada
351 St. Joseph Boulevard
12th Floor, Place Vincent Massey
Gatineau, Quebec K1AOH3
Environment Canada's Web site:
www.ec.gc.ca/cleanair-airpur/PollutionJssues/
Transboundary_Air/Canada-_United_States_Air_
Quality_Agreement-WS83930AC3-l_En.htm
In the United States:
Clean Air Markets Division
U.S. Environmental Protection Agency
Mail Code 6204J
1200 Pennsylvania Avenue, NW
Washington, DC 20460
U.S. Environmental Protection Agency's Web site:
www.epa.gov/airmarkets/progsregs/usca/index.htm
Office of Air and Radiation
EPA-430-K-08-011
1200 Pennsylvania Avenue, NW (6204J)
Washington, DC 20460
www.epa.gov/airmarkets
February 2009
Recycled/Recyclable—Printed with vegetable oil based inks on 100% postconsumer, process chlorine free recycled paper.
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