Ground Level Ozone
Annual O  means appear to be fairly consistent over the
the composite mean for the rest of  the province, which
3
past five years.  Looking back further, particularly at the
also has seen a gradual increase in the ozone concentra-
Front St site, it appears there has been a slight and
tion levels.
gradual increase in the annual means.  This is similar to
TABLE 34
Annual Mean and Maximum 1-hour O  Concentrations and Number of  Times
3
above the 1hour AAQC- Recorded at Two Monitoring Sites in Sarnia
1-hr AAQC 80 ppb
Location
Front St.
River Bend
Year
Annual
Max 1h
Number of times
Annual
Max 1h
Number of times
Mean
(ppb)
above 1h AAQC
Mean
(ppb)
above 1h AAQC
1990
17
98
6
23
110
51
1991
19
126
28
23
129
56
1992
21
111
18
24
131
64
1993
22
129
20
23
108
36
1994
23
110
21
25
113
81
1995
23
129
54
23
115
53
1996
22
100
45
24
128
98
1997
22
100
16
24
125
46
1998
22
111
33
26
122
101
1999
21
132
35
28
121
159
2000
20
103
10
24
118
23
2001
20
131
35
26
124
81
2002
21
116
76
26
142
138
Data not available for 8-hour averaging time period
The Front St. monitoring site is located in close proxim-
the scavenging effects of  NO .
x
ity to industry and ozone levels are likely influenced by
43