EXECUTIVE SUMMARY
In its charge to the International Air Quality Advisory
Ambient concentrations of selected HAPs in Ontario
Board, the International Joint Commission requested an
were largely below the MOE guidelines; however, a
overview of  the issues, control programs and binational
review of  the continued validity of  some of  the Ministry
or other cooperative efforts underway focused on
ambient guidelines appears appropriate.  For example,
transboundary  air quality in the Detroit-Windsor, Port
carbon tetrachloride is the only HAP whose concentra-
Huron-Sarnia and Sault Ste. Marie (Michigan and
tions approach the provincial objective; however, that
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Ontario) locales.
to
objective had been revised in 2001, from 600 µg/m
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over a 24-hour period.  Several HAPs are also
2.4 µg/m
In response, recognizing the longstanding Commission
at concentrations in excess of  those associated with the
interest in both common and hazardous air pollutants in
one-in-one-million life time cancer risk benchmark in
two of  these locales, the Board has secured and analyzed
the Clean Air Act.  A reconsideration of other MOE
data on ambient concentrations of  ozone, particulate
guidelines for hazardous air pollutants in light of the US
matter, sulphur dioxide, nitrogen oxides and total
Clean Air Act benchmark and other more recent data
reduced sulphur, as well as concentrations and emissions
would be timely.
of  selected hazardous air pollutants in the three regions.
The Greater Detroit area is one of  10 US urban com-
Based on the partial data available, elevated concentra-
munities in which an extensive monitoring program for
tions of  common air pollutants, particularly ozone and
ambient concentrations of selected HAPs has been
particulate (constituents of  smog) continue to occur
completed.  Evaluation of  the data, including an assess-
with some frequency, particularly in the summer months,
ment of  the associated risk against the one in one
in the three regions, adversely affecting human health,
million lifetime cancer benchmark in the US Clean Air
particularly among sensitive subpopulations (asthmatics,
Act, is underway.
youth, the elderly).
In all cases, the existence of  distinctly different air
The regional contribution to smog concentrations is
quality standards and guidelines under the federal, state
significant; the most recent Canada US Air Quality
and provincial regulators made a uniform assessment of
Agreement has recognized that these three locales are
prevailing air quality difficult.  While the national
within the area requiring a joint PEMA (Pollution
standards and objectives for ozone and particulates have
Emission Management Area) or regional approach to air
converged in the past few years, significant distinctions
remain.  In the case of  hazardous air pollutants, the
quality management.  However, the local contribution of
need for further review of  some of  the jurisdictional
both mobile and stationary point and areal sources is
guidelines, as noted above, is also evident.
also substantial, particularly in the Detroit-Windsor and
Sarnia-Port Huron locales and sizable reductions in
these inputs also appear necessary to markedly reduce
Findings
the deleterious impact on public health.
i)
While the data reviewed were not the most current
With regard to hazardous air pollutants (HAPs), a
nor comprehensive, it is clear that, in all three
review of  available emissions data for the three locales
regions, during episodes that occur with some
indicates that, in the case of  Detroit-Windsor and Port
frequency, particularly in the summer months, smog
Huron-Sarnia, emissions of  many of  the HAPs consid-
(ozone and fine particulate) achieves levels that
ered by the Commission in its 1991 Study appear to
would affect the well being of  the entire population
have been reduced; however, trichloroethylene and
and have an immediate, pronounced negative impact
xylene compounds remain at or above levels estimated
on the most sensitive elements of  the populations
in the earlier report.  In the Sault region, there is
youth and the elderly.  Similar conditions are evident
particular concern regarding PAH emissions from the
in the past few years and appear to persist to this
coke ovens of  the Algoma Steel facility, and ambient
day.
concentrations associated with these emissions are
being closely tracked.
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