More recent partial data indicate that the 1-hour AAQC
The influence of  TRS on the number of  hours the air
(80 ppb) was exceeded for 63 hours in 2001 and 153
quality was in the moderate to poor category, as determined
hours in 2002 at the downtown station.
by the AQI, was the greatest in 1997, 1998, and 2000.  TRS
measurements at Windsor West (College St. Site) reflect the
presence of  a significant point source nearby; the industrial
TABLE 17
Trend for Ozone (O
complex on nearby Zug Island off  Detroit and the sewage
) Annual Mean
3
treatment/sludge composting facility in West Windsor are
(ppb)
deemed to be the most likely source.
(No Annual AAQC)
Year
Station
At the Wright/Water St. site, the annual mean TRS levels
Windsor-Downtown
were also variable and similar in magnitude to those
reported for the Windsor West (College St. site).  There
1991
17.6
1992
15.1
was a discernible upward trend during the 1990s.  During
1993
17.1
the review period (1990-2001), a total of  87 hourly aver-
1994
18.0
ages exceeded the provincial objective; the majority were
1995
18.3
recorded during the second half  of  this period.  The close
1996
20.4
1997
20.7
proximity of  the site to Windsor West suggests that it is
1998
21.4
also influenced by the industries on Zug Island and the
1999
21.7
sewage treatment/sludge composting facility in West
2000
18.6
Windsor.
(OMOE-Air Quality Report-2000)
Ground Level Ozone (O )
The annual means recorded at the Windsor Downtown
3
site (University Ave.) reveal a slight and gradual increase
At the Windsor West site (College St.), the number of
over the reporting period.  The mean for the period
hours measured above the provincial hourly AAQC in
1995 to 1999 was about three ppb higher than during
the reporting period between 1990-2001 was quite
the period 1990 to 1994.  This is reported to be similar
variable, ranging from 168 hours in 1991 to 13 hours in
to the composite 10 year trend for 22 sites across the
2000.  The 1-hour AAQC of  80 ppb was exceeded on
province, which shows an increase of  one ppb in the
765 hours during the reporting period.  The frequency
second half  of  the decade.  The exceptionally cool
of  exceedance of  the AAQC peaked in 1991, 1996 and
temperatures during the summer months of year 2000
1999.  The highest hourly average was recorded in 1991
deceases the occurrence of  ozone, thus, this year has a
(127 ppb).  For this site, the annual means ranged from
lower annual mean.
16 to 21 ppb, with no discernable trend throughout the
years 1991-2000.
As ozone tends to be a regional issue, it is not inherently
clear what accounts for the difference in the trend
At the Windsor Downtown site (University St.), the 1-
between the Windsor West and Windsor Downtown
hour AAQC was exceeded for 662 hours during the
sites, with Windsor West having no discernable trend
reporting period.  The highest hourly average (139 ppb)
and Windsor Downtown have a slight trend upwards.
was recorded in 1994.  As also seen at the Windsor West
The differences may be attributed to traffic trends;
site, the number of  hours recorded above the provincial
further investigation would be required to make an
1-hour AAQC of  80 ppb was highest in 1996, 1998 and
accurate conclusion.  Ozone formation is also heavily
1999, which supports the observation of  generally
dependent on meteorological conditions, which would
higher ozone concentrations in the second half of the
account, to some extent, for the year-to-year variability.
review period as well as the variability of  concentrations
with varying meteorological conditions.  During this
period, the increased influence of  ozone in the determi-
nation of  moderate to poor air quality, as calculated by
the AQI, was observed.
24