Canada-Wide Standards (CWSs) for particulate
matter (PM) and ozone were passed at a meeting in Quebec City
in June 2000. The ozone standard is the 3-year average of the
4th highest daily maximum 8-hour average concentration set at
a level of 65 ppb. In addition to the 8-hour ozone standard,
a Canadian PM2.5 standard of 30 ug/m3 for 24 hours at the 98th
percentile averaged over 3 years was passed. The compliance dates
for both standards is 2010. Additional information can be found
by clicking here.
The Canadian ozone standard is near natural
background ozone levels. Although there are provisions in the
implementation of the ozone standard
to consider background levels, the ability to achieve the ozone
standard is very much in doubt. Science appears to have played
a minor role in determining the level of the proposed ozone standard.
It appears that a regression has been done between the 3-year
average of the 4th highest 8-hour daily maximum concentration
and the daily hourly maximum concentration. The assumption is
that it is possible to develop a mathematical relationship that
results in the 3-year average of the 4th highest daily maximum
8-hour concentration of 65 ppb being comparable to the past Canadian
hourly objective concentration of 82 ppb. Experiences have shown
that such is not the case. The most current 8-hour maps illustrating
Canadian ozone exposures can be found in our mapping
The Canadian government has realized that,
in some cases, exceedances of the two standards may be due to
activities not related to environmentally derived Canadian air
pollution sources. In jurisdictions highly impacted by transboundary
air pollution from the United States, achieving the CWSs will
be strongly dependent on reductions of this transboundary contribution.
high background levels of PM and ozone that may occur through
natural events, such as forest fires, natural formation, and
stratospheric intrusion, will need to be considered in assessing
achievement of the CWSs.
Any party may withdraw
from the Canada-Wide Standards upon three month's notice. The
Canada-Wide Standards come into effect on the date of signing.