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Progress on Ground-Level Ozone

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Canada and the United States signed the Ozone Annex to the Air Quality Agreement in December 2000 in Washington, DC. The Annex is expected to result in significant reductions of ozone precursor emissions of NOx and VOCs. These reductions will help both nations attain their respective air quality goals to protect human health and the environment. The Ozone Annex established a transboundary region, known as the Pollutant Emission Management Area (PEMA), which includes central and southern Ontario, southern Quebec, 18 U.S. states, and the District of Columbia. The provinces and states within the PEMA region are the areas of primary concern for the impact of transboundary ozone.

Figure 5. Ozone Annex Pollutant Emission Management Area (PEMA)

Figure 5. Ozone Annex Pollutant

In 2002, Canada and the United States met the first reporting requirement: ambient air concentration data for ozone, VOCs, and NOx were collected from monitoring stations within 500 km (310 miles) of the Canadian/U.S. border. These data were then analyzed to determine ozone conditions in the eastern and western regions of Canada and the United States.

Domestic Programs

To support its committed measures in the Ozone Annex, Canada will expand the National Pollutant Release Inventory (NPRI) to include annual public reporting of ground-level ozone precursors and components of smog. Other domestic measures in Canada include the Sulphur in Diesel Fuel Regulations and the On-Road Vehicle and Engine Emission Regulations. In addition, the Canadian provinces of Quebec and Ontario have made progress in meeting their commitments under the Ozone Annex.

To further protect against adverse health effects, the United States revised the National Ambient Air Quality Standards (NAAQS) for ozone in 1997. In addition, the United States is planning to designate new nonattainment areas for ozone. The United States is also continuing to implement regulations under the ozone transport reduction rule (known as the NOx SIP Call), which focus on the regional transport of ground-level ozone.

Each U.S. state containing a nonattainment area for ozone is required to submit a demonstration plan to meet the NAAQS for ozone. In addition, northeastern and mid-Atlantic states and the District of Columbia in the Ozone Transport Region (OTR) are implementing various strategies to reduce regional air pollution. As of 2002, NOx emissions from power plants and industrial sources in the OTR have been successfully reduced by more than 60 percent from 1990 levels.

Ozone Concentrations in Canada and the United States
(Based on ozone monitoring data from the period 1990-2001)

Figure 6. Eastern Regions

Figure 6.  Eastern Regions

legend of ppb

Figure 7. Western Regions

Figure 7.  Western Regions

legend of ppb


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