3
half  of  this period, the annual means at both sites were
of  65 µg/m .  However, the annual averages are in
usually greater than or equal to the objective of  0.3 ng/
excess of  the lifetime exposure benchmark (0.077 µg/
3
3
3
m
m ) for this contaminant under the Clean Air Act.
(or 0.0003 µg/m ) for all area sources and greater
3
3
(0.00022 µg/m ) for
than the objective of  0.22 ng/m
The 1994 Windsor Air Quality Study contained an
single sources.  In most years, the 24-hour objective of
3
was exceeded, with the exception of  the last
1.1 ng/m
estimate that Windsor contributed only four percent of
two years during the reporting period.
the total formaldehyde emissions in the Detroit-Windsor
airshed.  The presence of  petroleum refineries and
The 1990 Detroit-Windsor/Port Huron -Sarnia Air
Detroitís larger emissions from industrial sources of  fuel
Pollution Advisory Boardís report to the International
combustion are considered to be responsible for this
Joint Commission suggested that approximately 60
difference.
percent of B(a)P emissions for the entire region are
attributed to mobile sources while in the vicinity of 39
Trichloroethylene
percent are attributed to utilities and fuel combustion.
3
24-hour Provincial AAQC is 115 µg/m
Dioxins and Furans (PCDDs/PCDFs)
3
The provincial objective is 115 µg/m , well above the
3
maximum values of  0.36 and 0.54 µg/m  recorded in
1999 and 2000 respectively.  The annual means were 0.15
Annual mean concentrations of  total PCDF (furans)
3
3
and 0.17 µg/m
and total PCDD (dioxins) varied from about one pg/m
.
3
3
3
to 4.9  pg/m  and from about 1.4 pg/m  to 3.8 pg/m
respectively.  For both substances, the annual means in
the second half  of  the reporting period were consider-
ably lower than in the first half  (a 66 percent decrease in
2.1.6
Hazardous Air Pollutants:  Semi-volatile
total PCDF and a 46 percent decrease in total PCDD).
Organic Compounds (SVOCs)
Data were not available for 1997.
Benzo(a)pyrene (BaP)
The results were converted to a toxicity equivalent
(TEQ).  It is evident that the TEQs were considerably
Benzo(a)pyrene (BaP), a Polycyclic Aromatic Hydrocar-
lower in the second half  of  the reporting period, (1995-
bon (PAH), is one of  the International Air Pollution
2001).  The annual maximum 24-hour concentrations
Advisory Board for the Detroit-Windsor/Port Huron-
3
varied from 0.10 to 0.83 pg/m ; the Ontario 24-hour
Sarnia Region chemicals of  highest concern relative to
3
guideline (5 pg TEQ/m  ) was not exceeded in any year
direct inhalation.  Measurements were undertaken
of  the review period (1990-2001).  This trend in ambient
between 1990 and 1994 at the Windsor Downtown Site
concentrations of  dioxins and furans has been observed
(University Ave.) and between 1990 and 2001 at the
at a number of  other sites that are part of  the National
Windsor West Site (College St.).  The annual means for
Air Toxics Monitoring Program; however it appears to
3
BaP were typically between 0.3 and 0.5 ng/m .  Pres-
be more pronounced in Windsor.  The addition of  new
ently, no data are available for 24-hour concentration
control technology at the Greater Detroit Resource
levels.  The Provincial Annual Mean AAQC for
Recovery Facility in the mid-1990s may have contributed
3
benzo(a)pyrene from a single source is 0.22 ng/m
to the decrease in the ambient levels of  these substances
3
(0.00022 µg/m ); the 24-hour AAQC for a single source
in the west end of  Windsor.
3
3
is 1.1 ng/m  (0.0011 µg/m ).  There is a Provincial
Annual mean AAQC for Benzo(a)pyrene from all
3
sources, which is 0.0003 µg/m .  There is no 24-hour
AAQC for all sources.
2.1.7
Windsor Air Quality Study -1994
The larger data set from the Windsor West Site (College
In the fall of  1994, the Ontario Ministry of  Environ-
St.) suggests a downward trend in concentrations over
ment (MOE) published the Windsor Air Quality Study
3
time, with annual means less than or equal to 0.3 ng/m
(Ref. 31).  The ultimate aim of  the study was to Ňde-
in the latter part of  the monitoring period.  In the first
29