Ontario 2000 Ozone Animations & Maps


What the maps mean

These animations and maps were produced from Ontario government ground-level ozone measurements (daily peak readings) on the Web (http://www.airqualityontario.com/) using a weighted average interpolation technique to estimate values between the 16 measurement sites. Here's an example of one of the data sets from which we constructed our maps.

We used the same raster bitmap of Ontario as the Ont. Govt. does for direct comparability. Our map is overlain atop this bitmap.

The interpolated data was then rendered using a color scheme in which a continuous gradation of colors was assigned, with deep blues for very low readings, to deep reds for readings near or exceeding the provincial standard. Our color scheme:

Note: this is a different range of color values from those used by the Ontario government or the EPA. Our range is similar to the government scheme at low pollution levels, but shows more details during high pollution episodes. We based our scale on abundant medical and epidemiological data showing that health is effected for many people at levels below the provincial standard. The Ontario government's scheme is shown below:

Their scale is chosen to present a very simple picture - but most of the information about what's happening when air is in the poor quality zone - readings from 32 to 80 - can't be seen because they use only yellow and orange for this range. 

To better show this area of greatest concern we used a spectrum of colors, so more of the variation can be seen. Our coloring becomes reddish on the worst air quality days we experience, days when significant numbers of people with sensitivities will experience some problems. To see the difference, click on the two thumbnails below to see their view (left) and our view (right) of one day with bad air.

C4E3S100R8002000-06-10.jpg (41901 bytes)   <-- Ont. Gov't.                 Ours --> C3E3S100R8002000-06-10.jpg (46503 bytes)


One final note: although the EPA maps use the same color scheme as the Ontario government, they are based on different standards and so are not directly comparable.


For more details on how our maps were constructed, click here.




The animations show daily peak readings for a 11 day period in June during which a mass of low-quality air spread from the mid-western United States into Ontario (for comparison, see the EPA maps for the same period)


June 4-14,2000

animation: smaller images - 540KB

June 4-14,2000 animation: bigger images - 1.2MB





We've recorded example of good, poor, and bad air days throughout spring, summer, and fall of 2000 in Ontario. Each map is about 42 KB. We've purposely omitted many days with good air quality so the sample you see below is oriented towards showing you the worst.

May 17, 2000 a poor air day in spring
May 18, 2000 poor air near Erie and Huron shores
May 21, 2000 poor air in Muskoka in spring
May 22, 2000 poor air moves in from SW for Victoria Day
May 24, 2000 poor air everywhere for Queen Victoria's Birthday
May 30, 2000 poor air everywhere again
June 8, 2000 One of the worst air masses of the summer arrives from US
June 9, 2000 Bad air intensifies in SW Ontario but cottage country gets some relief
June 10, 2000 Bad air covers all of southern Ontario except for the eastern counties
June 14, 2000 After a short break, bad air returns to SW Ontario
June 26, 2000 Poor air in Kincardine, Tiverton,Long Point, and Muskoka
July 1, 2000 Poor air for us all for Canada Day!
July 2, 2000 Poor air worsens to bad in Grand Bend and Long Point
July 13, 2000 Poor air again
July 14, 2000 Ontario celebrates Bastille day by sending poor air to easter townships and Quebec
July 15, 2000 The way people expect it to be: poor air only in Greater Toronto area. This is the exception, not the rule
July 18, 2000 The way we'd like it to be: good air in all of Ontario
July 26, 2000 Poor air everywhere south of North Bay.
August 2, 2000 Yawn - more poor air everywhere for starting August
August 6, 2000 Poor air from the GTA to North Bay, just in time for the holiday weekend
August 14, 2000 Poor air everywhere except Toronto - see below for reason why
August 22, 2000 Poor air in Simcoe and Long Point - but farmers dont need to breath, do they?
August 28, 2000 Rare air: poor air only in Greater Toronto area.
August 29, 2000 The next day: poor air everywhere except Toronto
Sept 1, 2000 Fall begins with more poor air (except in North Bay - breath easy, Mike)
Sept 7, 2000 Labour day is past, but the pollution hangs on...
Sept 10, 2000 Poor air in Eastern Ontario
Sept 19, 2000 It's Tuesday, your kids are running in the schoolyard - in some of the worst air all year
Sept 20, 2000 Summer ends with a bang - very poor air in Ontario's biggest cities
Sept 21, 2000 Good air becomes more frequent in fall.
Oct. 1, 2000 Uniformly poor air to start October
Oct. 10, 2000 A fine October day with the wind from the north - good air
Oct. 12, 2000 Mild weather brings poor air from the U.S.
Oct. 14, 2000 Poor air for the whole Ontario shore - 4 million people plus
Oct. 16, 2000 A blast from the north brings really clean air
Oct. 20, 2000 A month into fall, poor air still hits SW Ont. from time to time.


Note: do cities have better air?

Why do cities such as Toronto, Windsor, and London often show "better" air than the rural areas around them? You can see this clearly in the map for August 14 .

This is a result of the atmospheric chemistry of smog production. Pollutants in cities, especially tailpipe emissions from dense traffic, actually temporarily reduce ozone concentrations in the immediate vicinity of large cities. Although ozone is less in the cities, the air is often actually more polluted by other pollutants such as small particles and volatile compunds.