Rural ozone concentrations in Alberta, Canada

Abstract

Three years of hourly ozone concentrations measured at mountain-top, slope and plains sites in rural Alberta, Canada yield an average annual concentration of 37, 28 and 26 ppb, respectively. Mean diurnal concentration ranges at the three sites were 3.4, 6.7 and 21.3 ppb, respectively. O 3 concentrations were a maximum in the spring and a minimum in the autumn with the corresponding monthly averages at Birch Mountain being 44 ppb and 27 ppb. At Birch Mountain hourly average concentrations exceeded 80 ppb with a frequency of 0.3%, daily average concentrations exceeded 25 ppb with a frequency of 89% and annual average concentrations exceeded 15 ppb with a frequency of 100%. The slope and plains stations had lower exceedance frequencies. Since these concentrations represent the hourly, daily and annual maximum acceptable levels of the Canadian Air Quality Objectives, a review of these objectives is suggested.