Long-term Trends

Over the past two decades, there have been a number of improvements and air quality control and monitoring technologies. These improved technologies have lead to improvements in air quality, especially in urban centres. In fact, levels of many air pollutants have shown significant declines over the past two decades:

Carbon monoxide concentrations have decreased by 61% in downtown Edmonton and 65% in downtown Calgary from 1982 to 2000. Annual average carbon monoxide values have decreased by 30 to 60% at other urban monitoring stations in Alberta.

Nitrogen dioxide concentrations have decreased by 32% in downtown Edmonton and 38% in downtown Calgary from 1982 to 2000. Annual average nitrogen dioxide levels have decreased by as much as 17% at other urban monitoring stations in Alberta.

Inhalable particulate (PM₁₀) values have decreased by 44% at the Edmonton Central station and 46% at the Calgary Central station from 1986 to 1999. Respirable particulate (PM_2.5) levels have decreased by 38 and 50%, respectively, at these two locations over the same time period.

Benzene concentrations have decreased by 52% in downtown Edmonton (1992 to 2000) and 30% in downtown Calgary (1991 to 2000). Annual average benzene levels have decreased by 51% at the Edmonton East monitoring station from 1991 to 2000. VOC monitoring began in the early 1990s at these monitoring stations.

Lead concentrations have decreased by 96% in downtown Edmonton and 98% in downtown Calgary (from 1980 to 1992). Because of very low concentrations, monitoring for lead was discontinued in 1992.

Sulphur dioxide concentrations have increased by about 2.2 times at the Edmonton East monitoring station from 1982 to 2000 and decreased by 26% over the same time period at the Fort McMurray station. Other significant trends in sulphur dioxides levels are not evident at Alberta Environment monitoring stations. It is expected that these trends are due to changes in industrial emissions over the last two decades. The annual average sulphur dioxide concentration measured in 2000 at the Edmonton East station (0.002 ppm) remains well below the annual Objective of 0.010 ppm.

	Long-term Trends Over the past two decades, there have been a number of improvements and air quality control and monitoring technologies. These improved technologies have lead to improvements in air quality, especially in urban centres. In fact, levels of many air pollutants have shown significant declines over the past two decades: Carbon monoxide concentrations have decreased by 61% in downtown Edmonton and 65% in downtown Calgary from 1982 to 2000. Annual average carbon monoxide values have decreased by 30 to 60% at other urban monitoring stations in Alberta. Nitrogen dioxide concentrations have decreased by 32% in downtown Edmonton and 38% in downtown Calgary from 1982 to 2000. Annual average nitrogen dioxide levels have decreased by as much as 17% at other urban monitoring stations in Alberta. Inhalable particulate (PM₁₀) values have decreased by 44% at the Edmonton Central station and 46% at the Calgary Central station from 1986 to 1999. Respirable particulate (PM_2.5) levels have decreased by 38 and 50%, respectively, at these two locations over the same time period. Benzene concentrations have decreased by 52% in downtown Edmonton (1992 to 2000) and 30% in downtown Calgary (1991 to 2000). Annual average benzene levels have decreased by 51% at the Edmonton East monitoring station from 1991 to 2000. VOC monitoring began in the early 1990s at these monitoring stations. Lead concentrations have decreased by 96% in downtown Edmonton and 98% in downtown Calgary (from 1980 to 1992). Because of very low concentrations, monitoring for lead was discontinued in 1992. Sulphur dioxide concentrations have increased by about 2.2 times at the Edmonton East monitoring station from 1982 to 2000 and decreased by 26% over the same time period at the Fort McMurray station. Other significant trends in sulphur dioxides levels are not evident at Alberta Environment monitoring stations. It is expected that these trends are due to changes in industrial emissions over the last two decades. The annual average sulphur dioxide concentration measured in 2000 at the Edmonton East station (0.002 ppm) remains well below the annual Objective of 0.010 ppm.