. "Atmospheric Changes Resulting from Transportation Activities." Atmospheric Change and the North American Transportation Sector: Summary of a Trilateral Workshop. Washington, DC: The National Academies Press, 1998.
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Atmospheric Change and the North American Transportation Sector:: Summary of a Trilateral Workshop
Figure3. Average measured concentrations of the air pollutants O3, NO2, and PM10 in selected cities during the years 1988-1993. The values in parentheses denote the number of monitoring sites used in each city. (Note that the U.S. NAAQS 03 limit will be changing to an eight-hour average of 80 ppbv.) From the Ontario Ministry of Environment.