Atmospheric and Climate Science Directorate

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The Scientific Basis for Clean Air Policy in the Lower Fraser Valley

Pacific 2001

The Lower Fraser Valley in British Columbia is often blanketed with smog in summer and autumn. Ground-level ozone and small airborne particles become trapped in the valley between the ocean and the mountains. Elevated levels of these pollutants can reduce visibility, adversely affect respiratory health, and damage vegetation and ecosystems.

Meteorological Service of Canada staff launch a tethersonde during Pacific 2001 to obtain detailed profiles of temperature, winds and humidity in the atmospheric boundary layer.

The chemistry associated with the formation of smog is very complex. By 2001, advancements in the science of measuring airborne particles and understanding their composition and atmospheric transport, enabled Meteorological Service of Canada MSC scientists to launch the largest intensive field campaign ever to take place in Canada – Pacific 2001. This field study involved 22 agencies, including Canadian federal, provincial, regional and U.S. governments, and 13 universities. The goal was to further the understanding of the physical and chemical processes that lead to particle formation in the Lower Fraser Valley airshed.

There are many air pollution sources in the Valley - emissions come from vehicles and industries in the Greater Vancouver area; from ships in the basin; from agriculture; and from industries in Washington State that are carried across the border. In addition, there are emissions from natural sources such as trees, vegetation, and the ocean. Emissions from all of these sources can react with sunlight to produce smog that can persist for several days.

An instrument deck used in the Pacific 2001 experiment equipped to measure various components of particulate matter.

During the study, measurements were made at five sites across the valley from Eagle Ridge to the Cassiar Tunnel, and from Langley to Golden Ears Park. Research balloons and aircraft were flown above the valley carrying instruments designed to help identify the nature and sources of urban smog.

Datasets collected during intensive field studies such as Pacific 2001 take 5 to 10 years to fully analyze and integrate into the knowledge of the science and policy communities. Analyses of the results will shed light on the complex chemical and physical processes of particle formation. To date, analyses have revealed that:

• The complex interaction of pollution with sea salt particles contributes to the impairment of visibility in the valley.
• Biogenic particles are prevalent, even in urban areas.
• Ammonia from agricultural and traffic emissions contributes to the formation of fine particles.
• Motor vehicle emissions contribute fine carbonaceous particles to urban air.

A previous study, led by MSC in the Valley in 1993 on ground-level ozone, contributed to the development of various emission control strategies, including vehicle tail-pipe emission testing. The 2001 study has produced an unparalleled database which will provide a strong foundation for air quality management policies in the Lower Fraser Valley well into the 21^st century.

The Lower Fraser Valley in British Columbia blanketed in smog.

“The Pacific 2001 study will provide the scientific underpinning we need to support policy development to protect this sensitive airshed.”
Hugh Sloan Director
Planning Fraser Valley Regional District

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