The Georgia Basin-Puget Sound Airshed Characterization Report 2014: executive summary
Table of Contents
- Executive Summary
- 1. Introduction
- 2. Fundamental Concepts of Air Quality
- 3. Air Quality and Weather
- 4. Air Quality and Social and Economic Trends
- 5. Emissions
- 6. Air Quality Monitoring
- 7. Ozone
- 8. Particulate Matter
- 9. Visibility
- 10. Regional Air Quality Modelling
- 11. Transboundary Transport
- 12. Atmospheric Deposition and Ecological Effects
- 13. Air Quality and Climate Change
- 14. Health and Socio-Economic Impacts of Poor Air Quality
The Georgia Basin - Puget Sound Airshed Characterization Report, 2014 was undertaken to characterize the air quality within the Georgia Basin/Puget Sound region, a vibrant, rapidly growing, urbanized area of the Pacific Northwest. Growth within this region continues to put stress on the environment, due to urban sprawl, increasing transportation demands, expansion of ports and new developments in the energy sector. These factors present significant challenges to managing air quality in the area.
The Georgia Basin - Puget Sound Airshed Characterization Report, 2014, is an update of the 2004 report by the same name and represents a synthesis of air quality work undertaken in the region since that time. The work is intended to provide scientific information to assist in the regional management of air quality in the Georgia Basin/Puget Sound international airshed. Its specific objectives are to:
- Identify and describe the key factors, natural and anthropogenic, affecting air quality in the region;
- Establish a current benchmark against which changes in air quality over the next 10 years can be measured;
- Determine if significant transboundary transport of air pollution occurs within the Georgia Basin/Puget Sound airshed;
- Describe the anticipated consequences on air quality of specific management actions;
- Describe the impacts of air quality on the ecosystem and on human health;
- Describe the impacts of climate change on air quality; and
- Provide a scientific basis for the development of public education and communication materials designed to enhance citizen understanding of air quality
in the region.
Georgia Basin-Puget Sound Airshed
The Georgia Basin/Puget Sound airshed is composed of two smaller airsheds, the Georgia Basin and the Puget Sound. The Georgia Basin portion comprises the Canadian portion of the airshed, as well as the north-western tip of Whatcom County and San Juan County in Washington State and the southern coastline of the Strait of Juan de Fuca. The Puget Sound portion encompasses the counties to the south of Whatcom County in Washington State.
Ground-level ozone, particulate matter and visibility are issues of concern in both the Canadian and U.S. portions of the airshed, and hence they form the focus of this report. Because these issues are matters of public concern, they are also among the principal foci of international cooperation between the two countries.
Fundamental Concepts of Air Quality
Air quality is a measure of the condition of the air and is primarily defined by the quantity of specific trace gases and particles present, with air quality declining with increased concentrations of these gases and particles. Ambient air quality is determined by emissions, chemical processing within the atmosphere and deposition or losses from the atmosphere. Sources of anthropogenic emissions include industry, transportation, home heating, use of pesticides and other agricultural activities. Natural sources such as vegetation, wildfires and wetlands can also emit both gaseous and particulate material into the atmosphere. Once emitted into the air, atmospheric processes and dynamics play a major role in the transport, dilution and transformation of gases and particles within the atmosphere. New secondary compounds, both gaseous and particulate, can be generated via physical processes or chemical reactions. Processes such as wet and dry deposition can remove various gases and particulate matter from the atmosphere. This can affect surface waters, soil composition, and the health of flora and fauna.
Both short and long term exposure to air pollution has been shown to contribute to illness and premature mortality. Effects are seen across a wide range of pollutant concentrations. Environmental damage to materials, vegetation and ecosystems also occurs due to pollutant deposition. As a result, ambient air quality is routinely monitored and compared to national, provincial and regional air quality standards, objectives and guidelines. The most common components of smog have been the focus of monitoring and regulatory efforts in both Canada and the United States. In Canada, this group of air pollutants is referred to as “criteria air contaminants” (CACs), while the U.S. uses the term “criteria air pollutants” (CAPs). The list of criteria pollutants includes oxides of sulphur (SOx), oxides of nitrogen (NOx), ozone (O3), carbon monoxide (CO) and fine particulate matter (PM2.5). The United States includes lead (Pb) in this list, while Canada includes volatile organic compounds (VOCs) and ammonia (NH3).
Air Quality and Weather
Air quality is heavily affected by weather patterns, which are influenced by local topography and variations in surface temperature and pressure. Once the pollutants become air-borne, the path by which they travel is controlled by global, regional and local processes and can have a strong role in determining the magnitude of air pollution concentrations at particular locations within the airshed.
Most of the air reaching the Georgia Basin/Puget Sound airshed has spent a number of days travelling over the Pacific Ocean. Consequently, pollutants are significantly dispersed or removed from the atmosphere by the time they impact the area. In addition, there are periods of time when air travels over parts of the continent before reaching the airshed. Both trans-Pacific and continental sources add to background levels of air pollutants in the airshed. Occasionally, the arrival of pollutants from Asia and elsewhere in North America can result in poor visibility and exceedences of air quality standards and objectives. The most likely time for air pollutants transported across the Pacific Ocean to enter the airshed is during the spring, particularly during April and May, when the upper level westerly flow is strongest.
A significant portion of the poor air quality days are associated with stagnant weather conditions in Georgia Basin and Puget Sound. Stagnation of air results in poor mixing and poor air flow with very little dilution of emissions. When these stagnation periods last over several days, pollutants can build to high levels. These periods of stagnation, which are often associated with surface-level inversions, often occur in the summer and winter, making these seasons more important for smog episodes. Wind flow patterns that are established during these stagnant periods do not allow much flow of air pollutants between the airsheds, effectively isolating one from the other. Occasionally local circulations limit the strength of the seabreeze and decouple flow between the Lower Fraser Valley and eastern Vancouver Island, as well.
Air Quality and Social and Economic Trends
The current social and economic trends in the Georgia Basin/Puget Sound airshed have the potential to contribute to a decline in air quality. These trends include urban sprawl, increased automobile use, increased energy consumption and increased international trade. Understanding these trends can help with modelling future air quality and identifying future policy directions.
Some of the major drivers of the economy, such as international trade, business, tourism and transportation produce a significant amount of air pollution and greenhouse gas emissions. For example, marine vessels and light duty vehicles are both major contributors to smog-forming pollutants. In addition, the agricultural industry is a contributor of emissions. Given past and projected social and economic trends in the Georgia Basin/Puget Sound airshed, the need to further improve and protect air quality is recognized by regional and federal agencies alike. Government agencies on both sides of the border are piloting various air quality management programs and developing emissions reductions plans to protect air quality in this international airshed.
Understanding the nature and quantity of air pollutants entering the atmosphere is essential for developing emission control measures. Emission inventories are important tools in providing information on the amount and location of pollutant emissions. Emission inventories can be used to forecast future emissions, based on projections of economic growth and changes in activity levels and technology, as well for planning emission reduction strategies.
Anthropogenic volatile organic compounds (VOCs) and nitrogen oxides (NOx) are the largest air pollutant emissions in both the Canadian Lower Fraser Valley and the Puget Sound. These emissions are largely from the transportation sector and include contributions from light and heavy duty vehicles, marine and non-road vehicles. Chemical product usage is also an important source of VOCs in the Canadian Lower Fraser Valley. Heating (including woodstoves and fireplaces) is a significant source of PM2.5 emissions in both the Canadian Lower Fraser Valley and the Puget Sound.
Emission forecasts conducted by the Western Regional Air Partnership indicate that emissions of some smog-forming pollutants (volatile organic compounds, nitrogen oxides (NOx), and sulphur dioxide) are expected to decline in the Puget Sound from 2002 to 2018. In contrast, emissions of ammonia (NH3) and fine particulate matter (PM2.5) are expected to rise in the area. Emissions of nitrogen oxides are estimated to decrease more than those of volatile organic compounds (VOCs), which could cause ozone to increase in VOC-limited urban areas. Natural emissions of volatile organic compounds are forecast to remain constant in the short term.
For the Canadian Lower Fraser Valley, Metro Vancouver’s most recent 2010 emission forecast is projecting declining volatile organic carbon and nitrogen oxide emissions until 2015 and 2025 respectively, as a result of stricter vehicle emission standards and improvements in fuel efficiency. Volatile organic compounds emissions are projected to increase after 2020 due to an increase in emissions from chemical product use. Sulphur dioxide emissions are expected to decrease significantly from 2010 levels due to the 2012 implementation of the International Maritime Organization Emission Control Area (IMO ECA) and marine emissions of NOx are expected to decline due to the implementation of IMO Annex VI Tier III standards for marine engines. Emissions of ammonia and coarse particulate matter are expected to rise during the 2010 to 2030 time period due to growth in the agricultural sector and construction industry, respectively.
Air Quality Monitoring
Ambient air quality is assessed by analyzing observations of air pollutants from air quality monitoring stations and other ambient measurements. In the Georgia Basin/Puget Sound airshed, air quality is monitored routinely by various air quality monitoring networks. The principal ambient air quality indicators tracked by these networks include gaseous pollutant concentrations, particle mass and composition and the surface deposition of contaminants.
In British Columbia, air quality is monitored by the National Air Pollution Surveillance Network (NAPS), the Canadian Air and Precipitation Monitoring Network (CAPMoN), the BC Ministry of the Environment (BC MOE) and the WISE Air Quality Monitoring Network (LFVAQN).
In Washington State, air quality is monitored by various networks which include: the Washington State Monitoring Network (WSMN), the National Atmospheric Deposition Program (NADP), the Clean Air Status and Trends Network (CASTNET), the Chemical Speciation Network (CSN) and the Interagency Monitoring of Protected Visual Environments (IMPROVE) network.
Detailed ambient measurements provide data on the trends and composition of air pollutants in the Georgia Basin/Puget Sound airshed, which is essential information for sound air quality management in the region.
Ground level ozone is a major environmental and health concern in the Georgia Basin/Puget Sound airshed. Ozone is not emitted directly into the atmosphere but is a product of a series of chemical reactions under the influence of ultraviolet light. Analyzing temporal and spatial trends and studying formation processes can lead to an increased understanding of the sources and management of ozone.
Concentrations of ozone at high elevation locations or at remote sites away from emission sources are primarily influenced by background sources. Studies show that background ozone levels are increasing on the west coast of North America, likely as a result of industrial growth in Asia and intercontinental transport.
Ground level ozone levels in most areas of the airshed are below national standards and regional objectives. The highest ozone concentrations are generally observed downwind of urban centers and at high elevations. Regional ozone episodes remain a problem in certain hot spots, such as Enumclaw, WA, and in the central and eastern portions of the Canadian Lower Fraser Valley, where national ambient standards have been periodically exceeded in the past decade.
Although peak ozone concentrations have declined in the Canadian Lower Fraser Valley since the 1980s, over the past two decades, ozone trends in the Lower Fraser Valley have been increasing up to the 90 or 95th percentile (location dependent) throughout the airshed. The consistent increase in these ozone trends is believed to be largely due to declines in nitrogen oxide emissions (resulting in a decrease in ozone titration) and possibly increasing background levels. In addition, although peak hourly ozone levels have declined in the eastern LFV, ozone exceedences continued to occur at Hope throughout the 2000s. Studies investigating the ozone reactivity regime in the WISE indicated that ozone formation is limited by the availability of volatile organic compounds most of the time, with the exception of high ozone episodes (ozone levels above the 95th percentile) when it is limited by the availability of nitrogen oxides in the eastern portion of the airshed. Given the spatial and temporal variability in the ozone reactivity regime, it is expected that ozone abatement efforts would require a tailored approach. For example, in the western LFV, additional volatile organic compounds reductions are expected to help reduce ozone levels on all days. In the eastern WISE however, because of the mixed ozone reactivity regime, volatile organic compounds reductions would be beneficial on days with ozone levels up to the 95th percentile, whereas additional nitrogen oxides reductions would be required when ozone levels exceed the 95th percentile.
Studies done to date indicate that most urbanized areas of the Georgia Basin/Puget Sound airshed appear to be limited by the availability of volatile organic compounds, while rural and wilderness areas appear to be limited by the availability of nitrogen oxides. Increasing background levels, changing emissions and resulting changes in ozone chemistry are some of the ongoing challenges to ozone management in the airshed.
Fine particulate matter (PM2.5) is of special concern due to its adverse effects on human health and visibility. Fine particulate matter can either be directly emitted into the atmosphere or be produced in the atmosphere from nucleation or condensation of gases. The principal air pollutants responsible for secondary formation of fine particulate matter include nitrogen oxides, sulphur dioxides, ammonia and organic carbon. In the atmosphere, these contaminants are transformed by chemical and physical processes to ammonium nitrate, ammonium sulphate and organic compounds, which are also the major components of fine particulate matter in urbanized portions of the Georgia Basin/Puget Sound airshed. Other components of fine particulate matter which are directly emitted include elemental carbon (from combustion of organic material), sea salt and fine soil.
At most monitoring sites in the airshed, ambient fine particulate matter concentrations peak in the fall and winter seasons, due to increased emissions from space heating and reduced dispersion under lower boundary layer heights. A peak in late summer is also observed at some sites due to enhanced photochemical conditions, favoring fine particulate matter formation.
Although fine particulate matter composition varies by location within the airshed, organic carbon was found to be the dominant component of particulate matter. In urban centers, approximately 50 percent of the particle mass is composed of organic and elemental carbon. Sulphate and nitrate combined, contribute to approximately one third of the mass of fine particulate matter in urban areas.
Key sources of ambient fine particulate matter in the airshed are vehicle and marine emissions, industry, agriculture and wood burning. Seasonal influences include wood burning during the winter, and increased cruise vessel activities and biogenic influences during the summer.
Although ambient fine particulate matter concentrations in the airshed are typically below national standards and objectives, certain areas, such as the Tacoma-Pierce County nonattainment area in Washington State, continue to experience exceedences of the fine particulate matter 24 hour NAAQS standard. Outside the non-attainment area, fine particulate matter shows evidence of a slight decline over time. Future ambient particulate matter concentrations will depend on changes in background levels, climate, and local and transported emissions.
Regional haze causes visibility degradation and detracts from the quality of the spectacular views in the Georgia Basin/Puget Sound airshed. As such, it can affect tourism and diminish the quality of life for residents.
In the Canadian Lower Fraser Valley and Seattle, the lowest observed visibility occurs in the fall, whereas at rural Mount Rainier it occurs in the summer. Seasonal and diurnal patterns of visibility are strongly affected by meteorological conditions such as relative humidity and boundary layer height. After adjustment for these two factors, the seasonal pattern of visibility in the Canadian Lower Fraser Valley showed that impacts due to anthropogenic pollutants are greatest during the summer months. Long term trend analysis indicates that visibility has improved in the Georgia Basin/Puget Sound airshed due to significant emission reductions over the past 40 years. Visibility measurements at four Class I areas in the Puget Sound show improving trends that are better than the expected rate of progress, based on visibility modelling.
In spite of improvements, visibility impairment is still an issue of concern, especially in the Canadian Lower Fraser Valley, where a recent perception study has shown that people experience unacceptable visibility conditions (visibility conditions that are perceived to be fair, poor, or very poor) 30% of the time.
The sources contributing to visibility loss vary according to the severity of the episode. In the Canadian Lower Fraser Valley, the organic carbon and nitrate fractions were higher during poor or worst-case visibility days, in comparison to all other days. Higher sulphate and organic carbon contributions were found at Mt. Rainier in Washington State during poor visibility days; however, contributions from these components have declined since the 1990s.
Air quality modelling has suggested that a number of emission reduction strategies could help improve visibility in different parts of the airshed. Ammonia-only reductions are expected to result in modest visibility improvements in the Canadian Lower Fraser Valley. This is a result of the large abundance of ammonia in the airshed due to intensive agricultural activity. Modelling work currently underway will more specifically inform visibility management efforts in the Canadian Lower Fraser Valley.
Because of the value that is placed on clear views of the surrounding landscape, the need to further improve and protect visibility is recognized by regional and federal agencies on both sides of the border. In the Georgia Basin, the British Columbia Visibility Coordinating Committee is managing a multi-faceted visibility program aimed at improving visibility in the Canadian Lower Fraser Valley, while in the Puget Sound compliance with the U.S. Regional Haze Rule ensures that progress is made towards protecting visibility in national parks and protected areas.
Regional Air Quality Modelling
Modelling regional air quality is essential for evaluating the effects of proposed emissions controls on ambient air quality. Five modelling case studies were reviewed, examining various air quality management issues relevant to the Georgia Basin/Puget Sound airshed.
Results of a study investigating the effect of various measures identified under the 2005 Metro Vancouver Air Quality Management Plan (Marine Emission Control Area, non-road regulations and reductions from large point sources) indicated that implementation of these emission reductions would result in declines in ambient concentrations of ozone and fine particulate matter in downwind areas of the Canadian Lower Fraser Valley. However, the study also found that these emission reductions could also result in an increase in concentrations of ground level ozone in metropolitan areas and marine traffic routes due to weaker ozone titration resulting from declining nitrogen oxide concentrations.
The study of ozone sensitivity in the Puget Sound (based on projected future growth and assumed use of low volatility gasoline) indicated marginal improvements to the summertime maximum 8-hour ozone by 2015. The use of low volatility gasoline was shown to play a minimal role in the improvements. Sensitivity analyses suggested that ozone formation in the dense urban areas and the polluted airshed west of the Cascades is limited by the availability of volatile organic compounds.
Modelling of agricultural ammonia in the Canadian Lower Fraser Valley showed that due to the abundance of ammonia in the airshed, the sensitivity of fine particulate matter concentrations to ammonia emission reductions is low. This suggests that reductions in ambient fine particulate matter would best be achieved by targeting multiple fine particulate matter precursors (volatile organic compounds, nitrogen oxides, sulphur dioxide), in addition to ammonia.
Modelling work done in support of the International Maritime Organization Emission Control Area (IMO ECA) designation for marine vessels indicated projected improvements in ambient ozone (in most areas) and in fine particulate matter over the Georgia Basin and parts of the Puget Sound, as a result of implementation of ECA regulations in 2012. Furthermore, nitrogen and sulphur deposition is expected to decline, and visibility is expected to improve as a result of implementation of new marine regulations.
Lastly, an examination of potential benefits of implementing the British Columbia 2008 Climate Action and Air Action plans throughout the province indicated expected declines in levels of fine particulate matter, volatile organic compounds, nitrogen oxides and sulphur dioxide. The most notable improvements in air quality and resultant health benefits are expected to be concentrated in the most populous parts of the province, i.e. Greater Vancouver and the Capital Region.
Due to the geography of the Georgia Basin/Puget Sound airshed, emissions from Canadian and U.S. portions of the airshed have the potential to affect each other’s ambient air quality.
Studies based on wind observations and back trajectory modelling indicate that pollutants cross the Georgia Basin/Puget Sound international boundary throughout the year. Under stagnant conditions, there is regular but very localized transboundary transport, particularly across the international border of the Lower Fraser Valley. Other flow patterns in the fall, winter, and spring, and during unstable periods in the summer, can carry pollutants and precursors across the international boundary on an episodic basis.
Modelling results indicate that local-scale air quality impacts from transboundary transport occur along the border (within approximately 50 km), with some frequency during the summer. Incidences of longer range regional transport (<100 km) are more frequent during the winter. It was found that, in general, Canadian and U.S. regions within the airshed exert a similar degree of influence on each other in terms of pollutant transport. Because of stagnant meteorological conditions associated with smog episodes, transboundary flows are not normally associated with exceedences of air quality standards and objectives on either side of the border. Air quality in the Georgia Basin/Puget Sound region can also be influenced by medium range transport of pollutants originating outside of the airshed. The most common examples include transport of forest fire smoke plumes from western North America.
Long range transport of pollutants across the Pacific contributes to background levels of ozone, fine particulate matter and other pollutants in the airshed. Asian dust events and large Siberian wild fires can have short-term detrimental effects on ambient air quality.
Atmospheric Deposition and Ecological Effects
Atmospheric deposition of air pollutants, such as sulphur, nitrogen and hazardous air pollutants, have adverse effects on both aquatic and terrestrial ecosystems. Some of these effects include acidification and eutrophication of surface waters, declines in forest growth and reduced species abundance and diversity. Recent studies in the Georgia Basin/Puget Sound airshed have examined the patterns, levels and impacts of dry and wet deposition of contaminants on various environmental receptors including soils, vegetation, forests, aquatic systems and terrestrial fauna.
Total sulphur and nitrogen loads have been declining since 1998 at both rural and urban locations in the airshed. This downward trend is mirrored in eastern Canada and the U.S., suggesting a wide-spread positive response to large-scale emissions reductions implemented in both countries. In spite of declining trends in both total sulphur and nitrogen deposition, localized areas of enhanced deposition still remain. Studies show higher levels of total sulphur deposition near marine shipping routes and major population centers. Hot spots are related to local industrial activities, such as oil refineries and aluminum smelters. Hot spots of elevated total nitrogen deposition occur in the Canadian Lower Fraser Valley, due to intensive poultry production and use of manure as fertilizer.
Studies showed that despite declines in sulphur and nitrogen loads, the levels of sulphur and nitrogen deposition exceed critical loads (deposition levels over which an adverse effect is expected) for various receptors in the airshed. For example, sulphur and nitrogen loads were found to exceed the critical load for soil acidity in the northern uplands of the Canadian LFV, where soils are thin and have a low buffering capacity. In addition, a study of 72 freshwater lakes located in the airshed found that 20% had a pH less than 6 (the level at which negative biological impacts are expected to occur) and that 18% of the lakes received sulphur deposition in excess of their critical loads. Other studies on forested ecosystems and lichens showed that these receptors experience regular exceedences of critical loads, particularly those close to or within the populated metropolitan areas under high atmospheric deposition.
Toxic or hazardous air pollutants (HAPs) are associated with serious health risks and ecological impacts. Several HAPs are readily deposited onto soils or surface waters, where they can be taken up by plants, ingested by animals and can eventually be magnified up through the food chain. Analysis of mercury concentrations in rainfall from several sites in the Puget Sound indicated that levels were highest at the Seattle/NOAA urban site. There was no significant temporal trend in mercury concentrations at this site, based on records dating back to 1996. Other studies which examined the average concentrations of total gaseous mercury measured in the Georgia Basin at Reifel and Saturna islands also indicated that atmospheric mercury concentrations have remained stable over the last decade.
Despite relatively low mercury levels found in air and in rainfall, there is evidence of bioaccumulation occurring at higher trophic levels. High concentrations of mercury were found in fish from the Olympic and Mount Rainier National parks, and some fish exceeded the human contaminant health threshold. Health thresholds for mercury were also exceeded in some instances for fish-eating otter, mink and kingfishers. The source of mercury at these high elevation locations is believed to be global long range transport. Higher levels of Persistent Organic Pollutants (POPs), such as Polychlorinated Biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PDBEs), were found at sites closer in proximity to industrial sources in the Puget Sound. Air-mass back trajectory analysis suggests that a portion of the PDBE load is from long range trans-Pacific transport.
Air Quality and Climate Change
Global change encompasses myriad effects of climate warming, changes in anthropogenic pollutant emissions and changes in land use and land cover due to climate effects, urbanization and land management decisions. Each of these aspects of global change has the potential to change air pollution levels on local to regional scales. Their impact on air quality can be investigated via dynamic downscaling of climate simulations and global chemical transport modelling.
Model simulations using the CMAQ (Community Multi-scale Air Quality) modelling system and the SRES A1B moderate growth emission scenario for the period 2045-2054 indicate that the cumulative effects of climate change, global and local emission changes and land use change will produce minor increases in ozone in the Georgia Basin/Puget Sound airshed. These changes can be attributed to the sum of the effects of climate change, including higher biogenic volatile organic compounds and nitrogen oxides emissions and to increases in background concentrations of ozone and its precursors from long range transport. Climate effects (meteorology alone) are projected to result in a net decrease in peak ozone values, but inclusion of the effects of warmer temperatures on northwestern biogenic emissions and change in land use produce a slight increase in ozone.
Model simulations using AURAMS (A Unified Regional Air Quality Modeling System) for the period 2041-2050 suggest that the impact of climate change under IPCC’s SRES A2 greenhouse gas emission scenario, assuming anthropogenic emissions remain constant, is one of degradation in air quality in the Georgia Basin-Puget Sound area. In contrast, the impact of reducing anthropogenic air pollutant precursor emissions using IPCC’s RCP 6 moderate-range stabilization scenario in a warmer future climate is one of improvement. Under this scenario, concentrations of ground-level ozone, fine particulate matter, sulphate, ammonium, nitrate, secondary organic aerosol, elemental carbon and the hydroxyl radical all decrease, the AirQuality Health Index improves, and deposition of ozone and acidifying sulphur compounds decline. The magnitudeof the potential improvements associated with the RCP 6 future air pollutant emissions scenario is projected to be greater than the magnitude of the deterioration due to a warming climate under current emissions. The results of these modelling studies suggest that air quality degradation due to climate change alone can be offset or reversed through emission reductions.
Health and Socio-Economic Impacts of Poor Air Quality
Poor air quality affects human health, natural ecosystems and diminishes the quality of life for residents. Recent new studies, some specific to the Georgia Basin/Puget Sound airshed, have provided an increased understanding of health-related impacts and have quantified economic losses associated with poor air quality.
Air pollutants affect human health in various ways, ranging from respiratory symptoms to premature death. Current levels of air pollution in the airshed have been found to have measurable health impacts. Increased exposure to air pollutants can potentially increase the risk of adverse birth outcomes, childhood respiratory disease and adult cardiovascular and respiratory disease.
The impact of a 10% improvement in fine particulate matter and ground-level ozone levels from a 5-year average baseline (1999-2003) in the Lower Fraser Valley and Whatcom County was estimated to provide approximately $293.6 million (2003 dollars, undiscounted) in societal benefits in terms of avoided negative health outcomes at year 20101.
Air pollution can harm natural ecosystems such as forests and water bodies. This may result in threats to biodiversity, reduced provision of ecosystem services, diminished recreational welfare or tourism revenues, and economic losses to resource-based industries, such as forestry, fishing and agriculture.
Implications and Recommendations
The report identified the following implications and recommendations for developing regional strategies to improve air quality in the Georgia Basin/Puget Sound airshed:
- Although emissions of smog-forming pollutants from the on-road vehicle sector are projected to decrease over the next decade on both sides of the border, emissions of volatile organic compounds, ammonia, and coarse particulate matter from chemical products usage, agricultural practices, and construction, respectively, are expected to increase.
- New international regulations governing emissions from ocean-going marine vessels, which began to be implemented in the Georgia Basin/Puget Sound airshed in 2012, are projected to reduce emissions of sulphur dioxide and nitrogen oxides from the marine sector. This is expected to have positive effects on ambient fine particulate matter levels, deposition of sulphur and nitrogen compounds and visibility. A slight disbenefit may occur in urban areas and marine waterways, where ozone may increase due to declines in nitrogen oxides, but this disbenefit is expected to be outweighed by other air quality benefits.
- Global energy requirements are increasing demands for marine shipping and associated rail and truck transportation. On-going monitoring of the impact of rapid growth in the energy sector is recommended, as the region engages in expanded economic activity in this area.
- Ozone continues to be an issue of concern in the Canadian Lower Fraser Valley and in areas of the Puget Sound in spite of consistent reductions in precursor emissions over the past two decades. These concerns are due to rising ozone levels at percentiles below the maxima, as well as hot spots where exceedences of ozone standards and objectives continue. Additional local volatile organic compounds control strategies may need to be considered in some urban areas. Selective nitrogen oxides emission reductions may be considered in downwind areas where ozone production is limited by the availability of nitrogen oxides during high ozone episodes.
- Fine particulate matter in monitored areas of the airshed is dominated by carbonaceous material (organic and elemental carbon). It is recommended that the regional management of emissions from combustion sources, such as transportation, industry and wood stoves, be a continuing priority to reduce fine particulate concentrations and related human health effects.
- Visibility continues to be an issue of concern in the Canadian Lower Fraser Valley, despite improvements over the past few decades. It is recommended that visibility improvement efforts focus on the summer period when the impact from anthropogenic pollutants is highest. It is expected that additional visibility improvements may be accomplished by reducing primary particulate matter emissions and black carbon from high emitters such as off road diesel engines. Recently implemented international marine vessel emission reductions are also expected to contribute to visibility improvements over the next decade.
- Pollutants move across the Canada-U.S. border during all times of the year, and this transboundary exchange of pollution is estimated to be relatively equal. Because of stagnant meteorological conditions associated with smog episodes, transboundary flows are not normally associated with exceedences of air quality standards and objectives on either side of the border. It is recommended that the transboundary flows of pollutants in the Georgia Basin/Puget Sound airshed continue to be surveilled, as the resource export industry grows on both sides of the border.
- Background concentrations of ozone, particulate matter, toxics and other pollutants contribute to the overall pollutant burden. It is recommended that background air quality continue to be monitored, particularly since background ozone is reported to be increasing on the west coast of North America.
- Trans-Pacific transport of Asian dust and Siberian forest fire plumes have the potential to contribute to exceedences of air quality standards and objectives in the Georgia Basin/Puget Sound airshed. This has implications for air quality management and compliance issues.
- Although sulphur and nitrogen deposition is declining, critical loads of these pollutants are being exceeded for certain soils, lakes and lichens in the Georgia Basin/Puget Sound airshed. This highlights the importance of continued efforts to reduce SO2 and NOx emissions.
- Atmospheric deposition of mercury, believed to be from long range sources, is causing exceedences of health thresholds for otter, mink and kingfishers in two national parks in Washington State. In addition, some fish from lakes in Washington State exceed the human consumption contaminant health threshold.
- Climate change occurring over the few decades is expected to have negative effects on air quality in the Georgia Basin/Puget Sound airshed, resulting in higher ozone, PM2.5 particulate matter, increased acid deposition and higher AQHI values. Reductions in air pollutant emission levels in line with those described under IPCC’s RCP6 scenario are projected to result in improvements in air quality. These improvements are estimated to be of a greater magnitude than the deterioration in air quality expected to occur under a warmer climate with current emissions.
- Ambient concentrations of air pollution at present levels in the airshed have been shown to have a negative impact on human health. Additional health and environmental benefits may be brought about by reductions in air pollutants.
1 Furberg, M. and Preston, K., 2005. “Health and Air Quality 2005 - Phase II - Valuation of Health Impacts from Air Quality in the Lower Fraser Valley Airshed”. RWDI Consultants in collaboration with Marbek Resource Consultants - Dave Sawyer; School of Occupational & Environmental Hygiene UBC - Dr. Michael Brauer; Dept of Health Care and Epidemiology UBC - Dr. Robin Hanvelt. Prepared for: BC Lung Association.
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