NOTE for TABLE 2: In July 1997, the U.S. EPA revised the National Ambient Air Quality Standard, establishing the threshold
value for both the primary and secondary 8-hour standard as 0.08 ppm measured as a maximum daily 8-hour average concentra-
tions. These standards were challenged by several business and state groups. In February 2001, the U.S. Supreme Court unani-
mously upheld the EPAs interpretation of its role in standard setting under the Clean Air Act.
emissions controls in the coarse-grid areas of
The United States EPA is to publish its ozone implemen-
Michigan would have little impact on 1-hour ozone
tation approach before designating areas for the eight-
concentrations as the levels are predominantly the
hour standard. At the present time, this implementation
result of upwind sources such as Chicago.
plan is not available as this rule is still in the approval
stage, and has not yet been finalized. State Implementa-
Additional Information on the Development
tion Plans (SIPs) for meeting the new standard are due
of the Canada-Wide Standard for Ozone
three years after final nonattainment area designations.
The U.S. EPA plans to designate eight-hour ozone
Studies undertaken by Health Canada concluded that
nonattainment areas on or about mid-2004, so ozone
statistically significant adverse health effects begin in
SIPs would be required approximately three years later
some portion of the population at ozone concentra-
tion as low as 15 ppb. This information prompted
the Canadian Federal government and Provinces to
The United States Ozone
examine the ozone guideline. Previously, the
Transport Reduction Rule
guideline was 82 ppb averaged over one hour. Of
the 22 mortality studies reviewed in preparation of a
The development of the Ozone Transport Reduction
background paper for the federal-provincial group
Rule, often referred to as the NOx SIP Call, is addressed
examining the guideline, 17 reported a consistent
in more detail in the Canada-United States Air Quality
and significant association between increases in
Agreement 2002 Progress Report. Briefly, the NOx SIP
mortality and ozone air pollution. The result of this
Call requires 19 eastern states plus the District of
review is the new Canada-wide Standard for Ozone,
Columbia to reduce their emissions of NOx, which
which is 65 ppb averaged over eight hours, to be
reacts with other chemicals in the air to produce ground-
achieved by the year 2010.
The State of Michigan is currently in the process of
submitting its revised SIP for NOx reductions. The
Sulphur Dioxide (SO )
revisions are the result of the EPA decision to modify
the NOx budget for Michigan. Facilities located in a
Ňcoarse grid area, an area largely outside of the
(Greater) Detroit region, would be allowed reduced
combustion of sulphur-containing fuels such as
emission controls as provided for under Section 126 of
coal, oil and vehicle fuels, and the heating of
the Clean Air Air. Section 126 authorizes Ňa downwind
materials that contain sulphur (i.e. certain
state, or political division thereof, to petition EPA for a
metallurgical and cement production processes).
finding that emissions from major stationary sources in
Diesel vehicles are a significant source of SO .
an upwind state contribute significantly to
nonattainment, or interfere with maintenance of a
NAAQS in the petitioning state. (Ref. 5). (The terms
SO contributes to the formation of fine
upwind/downwind refer to the relative orientation of
particulate aerosols and causes respiratory
two areas. The area in which the wind passes first is
discomfort and aggravation of existing respira-
upwind and the second area is considered downwind).
tory and cardiovascular disease in humans.
Modeling showed that implementation of NOx transport
Individuals with asthma, chronic lung disease or
heart disease are particularly sensitive to SO .