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Air Docket
United States Environmental Protection Agency
1301 Constitution Avenue N.W., Room B108
Mail Code 6102T
Washington DC 20004
Attn: Docket ID No. OAR-2003-0053
Proposed Rule to Reduce Interstate Transport of Fine Particulate Matter
and Ozone (Interstate Air Quality Rule)
Federal Register, 69 Federal Register 4565-4651 (January 30, 2004)
Submission filed by
Environment Canada
on
March 30, 2004
Executive Summary
Environment Canada is pleased to submit comments to the United States Environmental
Protection Agency (EPA) on the proposed Interstate Air Quality Rule (IAQR),
which is intended to reduce long-range and interstate transport of fine particulate
matter (PM2.5) and ozone.
Canada and the U.S. have a solid history of bilateral co operation to improve
air quality for our citizens. The 1991 Canada-United States Air Quality Agreement
and Annexes that are focused on acid rain and ozone reflect the significant
improvements that both countries are making to their nitrogen oxide (NOx), sulphur
dioxide (SO2) and volatile organic compound emissions. These emissions reductions
are leading to reductions in acidification and atmospheric concentrations of
ground-level ozone and particulate matter levels in both countries.
With regard to acid rain and ozone, despite the good progress made in both
countries, there is still much work to be done. Ozone concentrations in central
and eastern Canada are still well above the Canada-wide Standard level, and
further reductions will be required beyond those committed to in the Ozone Annex.
Further, most watersheds in the affected areas of Canada and the northeast U.S.
have not recovered from the effects of acid rain, pointing to a need for greater
reductions.
In addition to acid rain and ozone, particulate matter is also an important
air quality and health issue that both Canada and the U.S. have acknowledged
they need to address. Technical analyses in Canada and the U.S. conclude that
there are transboundary flows of particulate matter and its precursors from
the U.S. to Canada and from Canada to the U.S. To a certain extent, this is
being addressed by acid rain and ozone reduction measures, but further reductions
in Canada and the U.S. are necessary, particularly in regions where there is
transboundary flow.
Particulate matter and ozone are a national priority in Canada, because they
have been identified as contributing factors in thousands of premature deaths
across the country each year, as well as increased hospital visits, doctor visits,
and hundreds of thousands of lost days at work and school. The science demonstrating
the negative health effects of air pollution has been reconfirmed with the recent
publication of studies demonstrating increased risks of lung cancer and heart
disease from air pollution.
Environment Canada welcomes proposed action to further reduce emissions of
SO2 and NOx from electric generating units in the 29 eastern and midwestern
States and the District of Columbia, because of the resulting health and environmental
benefits on both sides of the border.
Environment Canada wishes to support the EPA for finding that 29 States and
the District of Columbia contribute significantly to non-attainment or interfere
with the maintenance of the National Ambient Air Quality Standards for PM2.5
and/or ozone in downwind States. Furthermore, Environment Canada supports the
EPA for proposing to require upwind States to revise their State Implementation
Plans (SIPs) to include control measures to reduce emissions of SO2 and/or NOx.
Environment Canada believes that the Interstate Air Quality Rule is a positive
step toward further reducing acid deposition, and will be helpful in improving
air quality in some regions of Canada.
At the same time, Environment Canada encourages the EPA to finalize the caps
with targets and timetables that are as aggressive as possible, and are implemented
as early as possible. In 2000, Canada put in place the Canada wide Standards,
which set out ambient levels for PM2.5 and ozone to be achieved by 2010.
The Canada-Wide Acid Rain Strategy for Post-2000 has a long-term goal to meet
the environmental threshold of critical loads for acid deposition across Canada,
in particular by establishing new targets and schedules for reducing SO2 emissions
in eastern Canada. To fulfill this commitment, from the base year 1994 Ontario
announced a target of 50% reduction by 2015, and has proposed to consult on
advancing the timeline to 2010; Quebec plans a reduction of 40% by 2002 and
50% by 2010; New Brunswick 30% by 2005 and 50% by 2010; and Nova Scotia 25%
by 2005 and up to 50% by 2010. Jurisdictions are now developing and implementing
measures to achieve these reductions.
Environment Canada recognizes the benefits of the proposed U.S. reductions
of 65% from Title IV allocations. However, Environment Canada would like to
note that, ultimately, further reductions will be required to reduce the impact
of acid deposition, with a goal of achieving a 75% reduction in SO2 emissions
from Title IV levels. The Department also wishes to point out that if timing
of the second stage reductions was advanced from 2015, this would provide additional
benefits to both countries.
The Canadian view is based on an acid rain research and monitoring program
in Canada, which indicates that about 70% of the sulphate and nitrate deposition
in Canada each year comes from U.S. sources. Even with full implementation of
the proposed Interstate Air Quality Rule, our watersheds and forests in eastern
Canada will continue to be damaged by acid rain. Reducing emissions further
and at a faster rate will slow the acidification of Canadian soils and prevent
the continued acidification of Canadian watersheds.
With respect to air quality, many studies in the U.S. and Canada indicate that
there is no apparent threshold for the harmful effects to human health caused
by PM2.5 and ozone. It is therefore critical to lower fine PM2.5 and ozone levels
not only as much as possible, but as fast as possible. Under prevalent meteorological
conditions, U.S. emissions contribute significantly to PM2.5 and ozone levels
in some regions of Canada. For instance, recent Canadian analysis confirms the
direct link between SO2 reductions in the U.S. with reductions in exceedances
of the PM2.5 standards in southwestern Ontario.
Environment Canada is very pleased to note that, when fully implemented, the
proposed IAQR would yield cumulative reductions of up to 34 million tons of
NOx and SO2 between now and 2015 (EPA, 2004). Those emissions reductions will
result in significant health and environmental benefits for Canadians and Americans.
Further, Environment Canada estimates that, if the U.S. were to advance the
caps such that both Phase I and Phase II were fully implemented by 2010, the
environment would be spared more than 2 million additional tons of SO2 and almost
1 million additional tons of NOx for the five year period.
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Introduction
Environment Canada is pleased to submit comments to the United States Environmental
Protection Agency (EPA) on the proposed Interstate Air Quality Rule (IAQR),
which is intended to reduce long-term and interstate transport of fine particulate
matter (PM2.5) and ozone.
Canada and the U.S. have a solid history of bilateral co operation to improve
air quality for our citizens. The first transboundary air pollution problem
was linked to acid rain in the 1920s, and the following 60 years were filled
with multiple volume assessments of the effects and controls of acid deposition.
The scientific consensus on aquatic effects played a significant role in justifying
sulphur dioxide (SO2) and nitrogen oxides (NOx) controls in Canada and internationally.
In the last 20 years, Canada and the U.S. have worked co operatively, first
with the 1981 Memorandum of Intent Concerning Transboundary Air Pollution, which
states the intention of both nations to develop a bilateral agreement on transboundary
air quality and to vigorously enforce existing air pollution legislation. The
two nations signed the 1991 Canada U.S. Air Quality Agreement, and an Annex
focused on reducing SO2 and NOx emissions to reduce acid deposition. The Agreement
contains emissions reduction commitments from existing programs in both countries,
the Eastern Canada Acid Rain Program and the U.S. Title IV Acid Rain Program.
Most recently, in 1997, Canada's Minister of the Environment and the U.S.
EPA Administrator signed a commitment to develop a Joint Plan of Action for
Addressing Transboundary Air Pollution regarding ground-level ozone and PM,
followed in 2000 by an Annex to the Air Quality Agreement on reducing NOx and
volatile organic compound (VOC) emissions, since they contribute to ground-level
ozone.
Great strides have been made in the last 20 years on reducing acidifying emissions
and improving air quality. However, Canada and the U.S. both acknowledge that
the problems are not solved. Both countries are taking further steps toward
reducing emissions that cause air pollution and acid deposition. Canada and
the U.S. are undertaking domestic programs to address PM, and are developing
a joint plan to identify transboundary contributions of PM and hope to soon
issue a report based on their findings.
It is important that the U.S. further reduce its emissions of NOx and SO2 as
quickly and as aggressively as possible, thereby contributing to the ongoing
Canadian efforts to achieve the Canada-wide Standards (CWSs) for ozone and PM,
two of the most important components of smog, and to prevent acidification of
Canadian ecosystems.
With respect to PM, ozone and acidification, and the effects of NOx and SO2
emissions on ambient air quality, human health, watersheds and forests in eastern
Canada, analysis makes the case that, for Canada, the targets and timetables
being proposed are a good step in the process of reducing these key pollutants,
but more accelerated action would be beneficial. Back to Top
Environment Canada's Concerns
Impacts on the health and environment of Canadians
The vast majority of Canadians live in regions of the country where there are
transboundary flows of NOx and SO2 pollutants that contribute to air quality
and acid rain problems.
Extensive scientific studies indicate that there are significant health and
environmental effects associated with PM and ozone. Particulate matter and ozone
are linked to serious health impacts, including chronic bronchitis, asthma,
and premature deaths. Other effects of these pollutants include reduced visibility
in the case of PM, and, in the case of ozone, crop damage and greater vulnerability
to disease in some tree species.
Many studies in the U.S. and Canada indicate that there are no apparent thresholds
for the harmful effects to human health caused by fine particulate matter (PM2.5)
and ground-level ozone. Therefore, it is critical to not only lower PM2.5 and
ozone levels as much as possible, but also as fast as possible.
Large parts of Canada have been receiving acid precipitation in the form of
rain, snow and dry deposition for at least 60 years, and deposition continues
to damage sensitive ecosystems. This is especially important in eastern Canada,
where wet and dry deposition of sulphur and nitrogen derived acids makes lakes
and streams unsuitable to support some fish and other biota.
Acid deposition also damages forest soils, by stripping the soil nutrients
and increasing the release of harmful substances such as aluminum, as well as
by directly damaging some sensitive tree species. Acids corrode buildings, statues
and sculptures, speeding the decay of these structures that are part of our
national heritage. The airborne pollutants that cause acid rain - tiny nitrate
and sulphate particles - are in the air we breathe and thus affect our health.
SO2 and NOx emissions and transport in the Canada-U.S. context
PM, ozone and acid deposition are related through common emissions and precursors,
production pathways, and meteorological processes. Emissions of SO2 and NOx
from fossil fuel power plants, smelters, motor vehicles, and other human related
sources are the principal contributors to PM, ozone and acid deposition.
Between 1980 and 2000, significant SO2 emissions reductions took place in eastern
Canada as a result of national and provincial programs aimed at reducing acid
rain and smog. Specifically, between 1980 and 2000, total provincial SO2 emissions
were cut as follows: Quebec by 70%, Ontario by 65%, New Brunswick by 75%, Manitoba
by 20%, and Nova Scotia by 12%. Nationally, total SO2 emissions have decreased
by about 50%, to 2.6 million tonnes in 2002. Nationally, NOx emissions have
decreased by 6%, more than 150 000 tonnes, since 1987.
Over a similar time period, as a result of the U.S. Title IV Acid Rain Program,
SO2 emissions from electric generating units have decreased by 41% (35% from
1990 levels). Emissions reductions from other sources have also contributed
to the 39% decline in total U.S. SO2 emissions since 1980. Title IV also specified
reductions in NOx emissions from electric generating units. Nationally, total
NOx emissions have decreased by 12% from 1990 through 2001.
However, SO2 and NOx emissions in the U.S. are about 10 times greater than
those from Canada, and can be transported hundreds of miles from their origin
in accordance with regional weather patterns. This long range transport is largely
responsible for acid rain in New England and eastern Canada. Several quantitative
trajectory and chemistry analyses strongly suggest that SO2 and NOx sources
in the U.S. are the major contributors to wet and dry deposition at sites in
eastern Canada. As illustrated in the following two figures, recent analysis
estimates that U.S. sources are responsible for about 65% of the total wet sulphate
deposition in eastern Canada, and almost 70% of the wet nitrogen deposition.
With regard to the air quality aspects of NOx and SO2, the occurrences of high
ozone and PM concentrations are, with few exceptions, part of contiguous, large
scale weather systems which originate in the U.S., then move northward the next
day to central and eastern Canada. Many analyses of this nature conducted by
Canadian and U.S. experts over the past number of years lead to the conclusion
by both countries that pollution transported within the international border
region is significant from an air quality and acidification standpoint. Indeed,
the inclusion of a defined Pollutant Emission Management Area (PEMA) for each
country in the Ozone Annex to the Air Quality Agreement reflects a recognition
that emissions reductions in these regions will have a positive impact on transport
of ozone and precursor emissions into each other's territory.
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Canadian SO2 and NOx Emissions Reductions
Canada has an integrated approach to addressing air quality, under which a series
of federal and provincial measures are being implemented to reduce pollutants
and their precursors, including SO2 and NOx. This includes the CWSs for PM and
Ozone, and the Canada Wide Acid Rain Strategy for Post 2000.
Canada-wide Standards (CWSs) for PM and Ozone
Driven by health concerns outlined in the preceding section, in June 2000 the
federal government, nine provincial governments, and the territorial governments
signed the CWSs for PM and Ozone. Quebec intends to act within its area of jurisdiction
in a manner consistent with the other Canadian jurisdictions, regarding these
CWSs and the deadlines for attaining them.
These CWSs commit governments to significantly reduce PM and ground level ozone
by 2010. The ambient Standards are 30 µg/m3 for PM2.5, and 65 ppb for
ozone. For PM2.5, achievement is based on the 3 year average of the annual 98th
percentiles of the daily 24 hour average concentrations. For ozone, achievement
is based on the 3 year average of the annual 4th highest of the daily maximum
8 hour average concentrations. In addition to the numeric targets and timelines,
the concepts of continuous improvement, pollution prevention and keeping clean
areas clean are elements of the CWSs.
The mechanisms for implementing emissions reductions necessary to meet the
CWSs are a shared responsibility of the Government of Canada and the provinces
and territories. Jurisdictional implementation plans will outline the comprehensive
actions required to achieve the CWSs by the 2010 target date. The nature of
provincial government measures to reduce CWS related pollutants varies, from
legislation and regulation of specific sectors and sources, to voluntary measures.
In meeting its obligations, the federal government published its implementation
plan for PM and ozone in 2001, which includes commitments to reduce emissions
of NOx and SO2. These actions include measures to reduce emissions from all
source sectors. In order to reduce emissions from transportation, Canada has
developed regulations and policies under the Federal Agenda on Vehicles, Engines
and Fuels that will lead to cleaner vehicles, cleaner fuels, new and different
fuels, more fuel efficient technology, and cleaner engines. These measures,
taken together, will lead to significant reductions in NOx and SO2, key contributors
to air pollution.
- On January 1, 2003, the new On-Road Vehicle and Engine Emission Regulations
were finalized and published in the Canada Gazette, Part II. These
Regulations are now phasing in more stringent emission standards for on road
vehicles and engines under the Canadian Environmental Protection Act,
1999, beginning on January 1, 2004.
- Regulations for engines found in lawnmowers, chainsaws, snowblowers and
other small tools and equipment were published in November 2003. Under the
new Regulations, these engines will be subject to new, cleaner emission standards
by 2005.
- Other regulatory proposals under development will address off road engines,
including those used in construction and agricultural equipment, marine crafts
and recreational vehicles.
- In addition, through the auspices of the Canadian Council of Ministers of
the Environment (CCME), Environment Canada co ordinated interprovincial co
operation and harmonization in the area of in use emissions from motor vehicles,
by developing the CCME Environmental Code of Practice for On Road Heavy Duty
Vehicle Emission Inspection and Maintenance Programs.
- The Sulphur in Gasoline Regulations limit the amount of sulphur
in gasoline to an average of 30 parts per million (ppm) in 2005. As an interim
step, gasoline with an average sulphur level of no more than 150 ppm was required
starting in July 2002.
- Sulphur in diesel fuel is being addressed through the Sulphur in Diesel
Fuel Regulations, which were finalized in July 2002. These Regulations
currently limit sulphur in diesel fuel used in on road vehicles to a maximum
of 500 mg/kg (or 500 ppm). In mid 2006, the limit will be reduced to 15 mg/kg.
These new Regulations were finalized on July 31, 2002.
- The Gasoline and Gasoline Blend Dispensing Flow Rate Regulations came
into effect on February 1, 2001, to limit the flow rate of nozzles used to
dispense gasoline and gasoline blends into on road vehicles.
Acid Rain
The goal of Canada's original acid rain program was to reduce wet sulphate
deposition1 to below a target load of 20 kg.ha-1.yr-1. Achieving this goal, as
a result of emissions reductions in both Canada and the U.S., was expected to
protect moderately sensitive aquatic ecosystems.
Canada's current commitment toward reducing acid rain causing emissions
is reflected in the Canada-Wide Acid Rain Strategy for Post-2000, signed by
federal, provincial and territorial Energy and Environment Ministers in 1998.
The Strategy provides the framework to address the remaining acid rain problem
in eastern Canada, and to ensure that new acid rain problems do not occur elsewhere
in Canada. The Strategy's long term goal is to achieve critical loads
for acid deposition to aquatic ecosystems. As steps toward achieving this goal,
the Strategy calls for a number of actions, including the development of further
controls on acidifying emissions in Canada. It also encourages further reductions
in the U.S. that are essential for success.
In fulfillment of the requirement to further reduce domestic emissions, the
provinces of Ontario, Quebec, New Brunswick and Nova Scotia all committed to
a further 50% reduction in their SO2 emissions beyond their Eastern Canada Acid
Rain Program targets, by 20102. Similar to the IAQR, eastern Canadian provinces
have the flexibility to choose the measures to achieve the specified emissions
reductions. Each of the provinces has taken significant steps toward identifying
measures for industrial sectors to achieve the specified 50% SO2 emissions reductions.
Back to Top
Current Environmental Picture
PM and ozone
Although measures are being implemented to achieve the CWSs for PM and Ozone
by 2010, ambient levels set out in the CWSs are regularly exceeded in many parts
of Eastern Canada (Ontario, Quebec and Atlantic Canada), as indicated by the
two figures below. In 2002, the CWSs for PM and Ozone (30 µg/m3 for PM2.5
and 65 ppb for ozone) were exceeded in most sites of eastern Canada, with a
maximum of 17 PM2.5 exceedance days and 49 ozone exceedance days. In terms of
the ozone CWS, almost all sites in Ontario and Quebec exceeded the CWS in 2002.
Year 2002 Exceedances of the CWS numerical levels for Ozone and PM2.5 across
Canada.
Number of days with Ozone Exceeding the CWS, 2002
[Click to enlarge]
Number of days with PM2.5 Exceeding the CWS, 2002
[Click to enlarge]
Acid rain
Critical loads are used to identify areas of acidification concern. Canada
established wet sulphate deposition critical loads, defined as the amount of
acid deposition that a watershed is able to tolerate while allowing 95% of the
lakes to maintain a pH of 6.0 or higher (Federal Provincial Research and Monitoring
Coordinating Committee, 1990). Across eastern Canada, critical loads range from
more than 20 kg.ha-1.yr-1 in the more tolerant watersheds, to less than 8 kg.ha-1.yr-1
in the most sensitive watersheds.
Despite the recent decreases in SO2 emissions, large areas of eastern
Canada continue to receive wet sulphate deposition in excess of the critical
loads. This figure illustrates the observed mean annual wet sulphate deposition
in eastern North America for 1996-2000. Levels range from less than 5 kg.ha-1.yr-1
to greater than 25 kg.ha-1.yr-1. The highest levels of wet deposition are observed
in the region of the Ohio River Valley. An analysis of wet sulphate deposition
data at three sites in eastern Canada - the Kejimkujik region in Nova Scotia,
the Montmorency region of Quebec, and the Algoma region in Ontario - showed
deposition exceeding critical loads by ~7 to 12 kg.ha-1.yr-1 (or 15 to 25 meq.m-2.yr-1)
(Jeffries et al., 1999).
Acid deposition model simulations using the Acid Deposition and Oxidant Model
(ADOM) that were carried out for 2010 - the year when all measures identified
in the Canada U.S. Air Quality Agreement will be fully implemented in both countries
- predicted that acid deposition will still remain above aquatic critical loads
by approximately 6-10 kg wet sulphate.ha-1.yr-1(Acidifying
Emissions Task Group [AETG], 1997; Environment Canada, 1997). Expressed in a
different fashion, an area of up to 800 000 km2 in southeastern Canada
will continue to receive harmful levels of acid deposition (AETG, 1997).
Additional predictive analyses by ADOM for 2010 show that even with implementation
of substantial local controls, i.e., a 50% reduction in Canadian SO2 emissions
beyond existing caps, an area almost 700 000 km2 would remain at risk. This
level of deposition is unlikely to allow widespread recovery of aquatic and
terrestrial ecosystems (Jeffries et al., 2003).
Based on these modelling and chemical analyses, it is clear that, despite the
Canadian and U.S. control programs that are codified in the Air Quality Agreement,
the impacts of acid deposition in eastern Canada have been neither eliminated
nor reduced to sustainable levels.
Several factors moderate a lake's response to declining sulphate deposition,
including declining base cations deposition, release of sulphur stored in the
lake's catchments, disruption of internal alkalinity generating processes,
and possibly a shift from sulphur based to nitrogen based acidification (Jeffries
et al., 2003).
There has been no improvement in nitrate deposition, due to a lack of reductions
in NOx emissions. Although nitrogen's influence on acidity status is currently
minor, the relative importance of acidification by nitrogen deposition will
increase in watersheds that are nearly nitrogen saturated as sulphur deposition
declines. The result may be an eventual erosion of the benefits gained from
reductions in SO2 emissions.
In many eastern Canadian watersheds, increasing levels of nitrate are being
observed in groundwater as it leaches from saturated soils. Recent attempts
have been made, under the Conference of New England Governors and Eastern Canadian
Premiers, to determine those acid deposition loads that are critical for maintaining
the existing soil buffering capacity (Arp et al., 1996; Ouimet et al., 2001).
Recent calculations of soil critical loads and exceedances (unpublished data
from the 2004 Canadian Acid Deposition Science Assessment) reflect the situation
where soils and forests are basically at steady state, and without harvesting
or fire adding to local soil acidification. Soils in southwestern Nova Scotia,
most of Quebec, and central and northwestern Ontario have low critical loads,
due to their low buffering capacity. Critical load exceedance is high where
atmospheric acid deposition rates are high, and where the critical soil acidification
loads are calculated to be low. Varying levels of exceedance are projected to
occur in most of the above low critical load areas, with the highest exceedance
levels projected for southern Quebec, especially north of the St. Lawrence River.
Locations with high exceedance are likely to experience poor forest health
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The Impact on Canada of the Proposed Interstate Air Quality Rule (IAQR) Emissions
Reductions
Under the proposed IAQR, electric generating units in 29 eastern and midwest
States and the District of Columbia would be required to cut region wide SO2
and NOx emissions. These cuts will result in SO2 reductions of 44%
and 50% by 2010 and 2015, respectively, from current electricity sector emissions.
For NOx, reductions of 56% and 63% from current electricity sector emissions
by 2010 and 2015 are projected.
Smog
From a transboundary perspective, the following information provides qualitative
estimates of ambient reductions needed to achieve the CWSs, and indicates that
under certain meteorological conditions commonly associated with high smog levels,
emissions from the U.S. significantly influence the ozone concentrations in
eastern Canada. The information also indicates that while the IAQR will contribute
to reducing ambient ozone concentrations, the proposed reductions will not be
sufficient to achieve the Ozone CWS in all parts of eastern Canada, particularly
in southwestern and central Ontario.
- Modelling results from a July 11-19, 2003, air quality episode using
the Community Multi-Scale Air Quality Model (RWDI Consulting Engineers, 2003)
for eastern Canada have been used to estimate the potential impact of Canadian
and U.S. emissions reductions on ambient levels of PM2.5 and ozone.
-
High ozone levels associated with this episode began in the southeastern
and midwestern U.S., and spread to eastern Canada. The large scale weather
conditions associated with this episode were representative of a class of
weather conditions that are commonly associated with high smog episodes
in the summer.
- A number of scenarios were modelled with this episode, including a 1995-96
base case scenario, a scenario that included Ozone Annex and Acid Rain commitments
(henceforth called the "Ozone Annex Scenario"), and a scenario with
U.S. emissions set at those proposed under the IAQR (the "Approximate
IAQR Scenario").
Approximate SO2 and NOx Emissions for the Eastern Canadian Provinces
and U.S. PEMA Area for the Scenarios Modelled in the July 1999 Episode.
Canadian Eastern Provinces* and US PEMA NOx and SOx Projections
for Various Scenarios
[Click to enlarge]
- A qualitative estimation of changes in values of the Ozone CWS was
obtained by adjusting the actual 8 hour average ozone concentrations (CWS
metric for 1999) over each of seven representative areas in eastern Canada,
by applying factors obtained from the July 1999 modelled episode for both
the Ozone Annex and approximate IAQR Scenarios.
- In 1999, six of the seven areas had an average level that was above the
CWS, ranging from a low of 12% above the CWS to a high of 32%.
- Under the Ozone Annex, the number of areas with levels above the CWS decreased
to five, and under the IAQR the number of areas estimated to be above the
CWS decreased to three. These latter three areas remained 6-12% above the
CWS, and are all located in southern Ontario.
The current (1997 - 1999) percentage above the CWS metric are indicated by
the green bars, for each of the seven representative areas. Six of these areas
exceed the CWS, ranging from a low of 12% above the CWS to a high of 32%. The
percentages above the CWS resulting from the implementation of the Ozone Annex
and IAQR are indicated by the blue and orange bars, respectively.
Percentage Above the Ozone CWS for Areas of Eastern Canada
[Click to enlarge]
Acid rain
Canada carried out additional model simulations using ADOM, a three dimensional
Eulerian chemical transport model, to determine the impact of specified SO2
emissions reductions across eastern Canada and the U.S. (Kaminski, 2002). The
scenarios explored the impact of possible post 2010 SO2 emissions control strategies
for eastern North America, i.e., beyond the Air Quality Agreement commitments.
The starting point for the U.S. SO2 emissions used in the scenarios were the
Phase II caps set under Title IV, assuming no geographic redistribution through
emissions trading. In terms of total SO2 emissions, the U.S. is assumed to reduce
its annual SO2 emissions from 2010 levels (12 446 Ktonnes.yr-1 within the ADOM
domain). All of the reductions were assumed to be linear rollbacks from all
sources.
Predictive analysis for post 2010 scenarios:
- combined with the 50% reduction in eastern Canadian SO2 emissions beyond
existing Eastern Canada Acid Rain Program caps, if U.S. SO2 emissions are
reduced by 50% beyond existing Title IV limits, the size of the area in eastern
Canada predicted to receive harmful levels of acid deposition would shrink
by about 70%; more than 240 000 km2 across Ontario, Quebec, New Brunswick
and Nova Scotia would still be receiving acid deposition above critical loads.
- by reducing SO2 emissions by 75% in the U.S. midwest and eastwards and
in eastern Canada, again beyond existing caps in both countries, acid deposition
would be reduced to below critical loads in virtually all of eastern Canada
(AETG, 1997); the area at risk is expected to shrink by 99% of the 2010 base
case. However, under this scenario, much of the area predicted to be in attainment
of the critical load is still within 2 kg.ha-1.yr-1 of critical loads.
Based upon the atmospheric deposition modelling, the results indicate that
the proposed emissions reductions in the IAQR are a good step to further reduce
acid deposition to lake ecosystems in eastern Canada. The additional reduction
in NOx emissions proposed under the IAQR will have co benefits in terms of reducing
acidification. However, more reductions will be required to fully address the
problem.
Canada is aware of the limitations of using wet sulphate deposition as the
primary environmental criterion for ecosystem protection, including the lack
of consideration of total deposition including nitrogen. A second limitation,
the use of wet deposition information only, results in an underestimate of total
deposition (wet + dry). Unpublished data (Vet, R., Meteorological Service of
Canada, personal communication) suggest that dry deposition may be underestimated
by as much as 20-35%. As a result, estimates of mapped exceedances will increase
even further, i.e., predictions of the area achieving the critical load as a
result of reduced emissions are overestimates.
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Conclusion
As stated, Canada and the U.S. have a solid history of bilateral co operation
to improve air quality for our citizens. However, despite the good progress
made in both countries, there is still much work to be done.
As evidenced in the foregoing material, impacts of acid deposition in eastern
Canada have been neither eliminated nor reduced to sustainable levels, and PM
and ozone levels exceed the CWSs in many regions of the country. Furthermore,
emissions of SO2 and NOx from Canadian and U.S. sources contribute significantly
to air quality and acidification problems in Canada.
Environment Canada would like to acknowledge the positive step forward that
the U.S. has proposed with the Interstate Air Quality Rule. Environment Canada
believes that this step will contribute to our continuing collaboration toward
meeting our goals to reduce the human health and environmental impacts of air
pollution. At the same time, Environment Canada encourages the U.S. EPA to finalize
the caps with targets and timetables that are as aggressive as possible, and
that are implemented as early as possible.
All information requests should be directed to:
Barry Stemshorn
Assistant Deputy Minister
Environmental Protection Service
Environment Canada
351 St. Joseph Boulevard
Gatineau QC K1A 0H3
Canada
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References
Acidifying Emissions Task Group. 1997. Towards a National Acid Rain Strategy.
Ottawa.
Arp, P.A.; W. Leger; M. Moayeri; and J.E. Hurley. 2001. Methods for mapping
forest sensitivity to acid deposition for northeastern North America. Ecosys.
Health 7: 35-47.
Environment Canada. 1997. Canadian Acid Rain Assessment, Volume 2, Atmospheric
Science Assessment Report. Ottawa.
Federal-Provincial Research and Monitoring Committee. 1990. The 1990 Canadian
Long Range Transport of Air Pollutants and Acid Deposition Assessment Report.
Part 4, Aquatic Effects. Ottawa.
Jeffries, D.S.; T.G. Brydges; P.J. Dillon; and W. Keller. 2003. Monitoring
the results of Canada/USA acid rain controls programs: some lake responses.
Env. Monitor. Assess. 88: 3-19.
Jeffries, D.S.; D.C.L. Lam; M.D. Moran; and I. Wong. 1999. The effect of SO2
emission controls on critical load exceedances for lakes in southeastern Canada.
Wat. Sci. Tech. 39:165-171.
Kaminski, J.W. (Atmospheric Research and Modelling Consultants). 2002. Emissions-scenario
simulations of new provincial SO2 reduction targets using the Acid Deposition
and Oxidant Model. Toronto.
Ouimet, R.; L. Duchesne; D. Doule; and P.A. Arp. 2001. Critical loads and exceedances
of acid deposition and associated forest growth in the northern hardwood and
boreal coniferous forests in Quebec, Canada. Water, Air and Soil Pollution:
Focus 1: 119-134.
RWDI Consulting Engineers. 2003. Air Quality Modelling for July 11 to 19,
1999 Modelling of Emission Scenarios (prepared for Environment Canada).
Guelph.
Also see:
Comment submitted to the U.S. Environmental
Protection Agency by Environment Canada: Proposed National Emission Standards
for Hazardous Air Pollutants; and, in the Alternative, Proposed Standards
of Performance for New and Existing Stationary Sources: Electric Utility
Steam Generating Units
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