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Ozone Levels

  OZONE LEVELS


Figure 3 shows ozone levels in the form of the CWS for Canadian communities and reporting sub-areas (RSAs) for the period 2003-2005.  Figure 4 shows the CMA, CA, CSD and RSA boundaries for these communities and areas along with their associated levels in comparison to the Standard.  The levels in these figures are as reported by provincial and territorial jurisdictions in accordance with the procedures detailed in the GDAD.
 
For the period 2003 to 2005, at least 40% of the Canadian population (approximately 13 million) lived in communities with levels above the CWS.  Most of these were located in Ontario and Quebec.  Outside these two provinces, only one community in British Columbia and one non-urban area in Atlantic Canada had levels above the CWS.  With the exception of Saskatchewan, Manitoba and the territories, all other regions had at lease one location with levels within 10% of the CWS (yellow range).
 
In the western part of Canada, ozone levels varied (Figure 3) from 44 to 68 ppb in British Columbia, 53 to 64 ppb in Alberta, 52 to 54 ppb in Saskatchewan and Manitoba, and at the single monitored community in the Northwest Territories, the level was 48 ppb.  In the eastern part of Canada, levels varied from 58 to 82 ppb in Ontario, 56 to 73 ppb in Quebec, and 46 to 69 ppb in Atlantic Canada.
 
It should be noted that in many communities of Ontario and Quebec, levels of PM2.5 and ozone above the numerical value of the CWS often occurred on the same days.  
 
 
 
                          Figure 3:  Ozone levels in the form of the CWS, 2003-2005


 


Notes:  Shown are the values of the 3-year average of the annual 4th highest daily maximum 8-hour average ozone based on the procedures in the GDAD.  Yellow band represents levels within 10% of the CWS.  In blue with* are communities with populations of 100,000 or less that jurisdictions elected to report on.  In green italic are non-urban monitoring stations.  Data provided by provincial and territorial jurisdictions, and generated from measurements collected through NAPS.  Data are preliminary and subject to change following further data quality assurance reviews.  




        Figure 4:  Map of Canada showing ozone levels in the form of the CWS, 2003-2005
 


Notes:  Shown are the values of the 3-year average of the annual 4th highest daily maximum 8-hour average ozone based on the procedures in the GDAD.  Blue-hatched areas have insufficient data.  Data provided by provincial and territorial jurisdictions, and generated from measurements collected through NAPS.  Data are preliminary and subject to change following further data quality assurance reviews.
 
 

PM composition
 
Particles typically consist of a mixture of substances.  Information on the measured composition of the particles is important as it can be used in a weight-of-evidence approach to identify the source-categories contributing to the ambient PM mass.  Health research is also increasingly pointing to the need to identify the PM components that may be responsible for the health effects.
 
Detailed measurements of the main PM specie on a routine basis are relatively recent and are limited in coverage across Canada.  This section presents results of a PM composition analysis for the current locations where PM speciation samplers are operated routinely.
 
Figure 5 provides an overview of the average PM2.5 composition for stations in British Columbia (B.C.), Ontario, Quebec and New Brunswick from February 2003 to August 2005.  During this period, total carbon (elemental + organic) was a major component of PM2.5 mass in each location, followed by sulphate and nitrate (in their ammonium-related forms).  Other minor components were soil elements and salt.  Secondary PM2.5 such as sulphate, nitrate and a portion of the organic carbon typically account for one half or more of the PM2.5 mass in eastern locations.  The B.C. locations generally reflected a greater predominance of total carbon than the eastern Canada locations.  It should be noted, however, that the actual day-to-day composition may differ substantially from this average, depending on the sources that contributed to the PM2.5 mass and the weather conditions that prevailed.
 
 

                        Figure 5:
  Average PM 2.5 composition for selected stations, 2003-2005      
 

           

Notes:  Data are for the period February 2003 to August 2005.  Data generated by Environment Canada from measurements collected through NAPS.  Sulphate and nitrate were assumed to be in their ammonium-related forms.  For Simcoe and Saint-Anicet, the Soil fraction is part of "Missing,” as estimates of the soil fraction were not possible for these two locations.  The same applied for most soil measurement at Canterbury.  Simcoe, Saint-Anicet and Canterbury are all in non-urban areas.  The PM composition analysis is based on widely used mass-reconstruction methods.

 
 

Annual Variation in PM2.5 Levels
 
It is important to know the long-term trends in the ambient levels of PM2.5 across Canada.  However, daily monitoring of ambient PM2.5 levels across all regions of Canada did not begin until the late 1990s, aided by the development and implementation of the CWS.  As such, a sufficiently long-term record of data does not exist to enable the evaluation of robust trends in PM2.5 levels.  However, a qualitative indication of how the levels varied over the ears is still possible.  This is accomplished here by presenting the regional range in PM2.5 levels in the form of the CWS for the period 2001 to 2005.  The regional range for a given year is defined as being the lowest and highest values of all considered station-specific levels in the form of the CWS for that year, along with the average of all the station-specific levels. 
 
From the late 1990s to 2005, the number of communities and areas covered by PM2.5 monitoring grew rapidly.  To provide a broad indication of the PM2.5 levels that prevailed in the regions, the number of communities and areas considered here was not constant, but was rather allowed to vary yearly depending on the availability of the data.  For this reason, and also because the PM2.5 levels presented here are not to be used for CWS achievement evaluation, the number of communities and areas considered in this section are larger than those considered in Section 4.2.  As such, the information in this section is not directly comparable to the information in Section 4.2.
 
 

Results
 
Figure 6 indicates the annual regional range (as defined above) in PM2.5 levels in the form of the CWS.  For most regions of Canada, average PM2.5 levels ranged from 15 to 20 µg/m3.  Notable exceptions are Ontario and Quebec, where regional averages either neared the CWS or were above it.  Ontario, Quebec and British Columbia are the three regions where the highest PM2.5 level was above the CWS in every year.  Elsewhere, the highest level was appreciably below the CWS except in Alberta and New Brunswick, where the highest levels approached the CWS in some years.  
 

Notes:  The PM2.5 levels shown are from continuous monitors, consisting of the TEOM® (the majority) and BAM monitors.  The highest and lowest levels shown are values of the 3-year average of the annual 98th percentiles of the daily 24-hour PM2.5.  These 3-year averages were computed for each monitoring station considered in the region and the highest and lowest of these were then extracted.  The Average is simply the average of all the station-specific 3-year averages in the region.  The numbers in brackets below the region’s name (N1/N2) are the number of monitoring stations considered during the first (N1) and last (N2) year of the period;   the number of stations considered for in-between years may have been fewer or more than these.  Years with only a circle and no range shown indicates that only one station was considered, and therefore no range is possible.  The monitoring method configuration may have changed over the years in some regions;   this may have affected the monitoring results and may have contributed to the annual variation in levels.  Data generated by Environment Canada from measurements collected through NAPS.      

 

 

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