The Georgia Basin-Puget Sound Airshed Characterization Report 2014: chapter 14

14. Health and Socio-Economic Impacts of Poor Air Quality

Jim Vanderwal, Amy Greenwood, Narissa Chadwick (Fraser Basin Council), Tracey Parker (Environment Canada), Patti Dods (Health Canada), and Rita So (Environment Canada)

Numerous health and environmental impacts are associated with poor air quality. This chapter provides a summary of these impacts and presents some of the existing studies and literature which examined these impacts in the Georgia Basin/Puget Sound airshed. Monetary values are presented for illustrative purposes and do not comprehensively characterize the total economic costs of air pollution nor the value of the impacted ecological goods or services within the Georgia Basin/Puget Sound region. Moreover, monetary values should not be aggregated since the timeframes and impacted endpoints may differ.

It should be noted that due to the scarcity of information on this topic, most of the information on the Canadian side of the border is specific to the Metro Vancouver area and the Fraser Valley Regional District (FVRD). Although these two areas comprise only nine per cent of the geographic area of the Georgia Basin, they are home to a large percentage of its population. On the American side of the border, the majority of available information is specific to Washington State.

14.1 Health Impacts of Poor Air Quality

Although air quality in the Georgia Basin/Puget Sound airshed appears to be relatively good in comparison with other urban regions in North America, current levels of air pollution have been found to have measurable health impacts (Karr et al, 2009; MacIntyre et al, 2011). Table 14.1summarizes the health effects of individual air pollutants and mixtures at current ambient levels of exposure.

Air pollutants affect human health in various ways, ranging from respiratory symptoms to death. Seniors, children, pregnant women and those with chronic disease are among those at greatest risk. For pollutants such as ozone and fine particulates, there is no known lower threshold for human health impacts. Therefore, the management of air pollutant levels involves making decisions that minimize, but do not necessarily eliminate, the health risk.

Section 14.1.1 will present the findings of studies on the health impacts of air pollution that were conducted as part of the Border Air Quality Strategy. Sections 14.1.2 and 14.1.3 will then address cancer and non-cancer related health impacts, based on other empirical studies.

Note: ¹in addition to particle effects

14.1.1 Border Air Quality Strategy Study

A recent initiative in the Georgia Basin/Puget Sound Airshed, the Government of Canada Border Air Quality Strategy, resulted in novel research projects in assessing individual exposure of poor air quality and health outcomes specific to the Georgia Basin/Puget Sound Airshed. The Border Air Quality Study was created to study the impacts of transboundary air pollution on human health and facilitate the development of a framework for coordinated airshed management. The objective of the research projects was to gain knowledge and understanding of the associations between increased exposure to numerous air pollutants and increased risk of adverse birth outcomes, childhood respiratory disease and adult cardiovascular disease. Unlike other studies, the Border Air Quality Study capitalized on the large population within the Airshed to investigate the relative effects of local high pollutant areas, health effects on sub-populations and subtle health impacts in areas with relatively low ambient levels of pollution. These latter effects may have been indiscernible in smaller studies. The results from these studies highlighted the opportunity for reducing adverse health outcomes through consideration of traffic and proximity to highways during urban planning, as well as strategies to reduce residential wood combustion emissions. As a large population-based study, results from this study can be extended to the entire population in the Georgia Basin Puget Sound region.

A summary of research results from the Border Air Quality Study is shown in Table 14.2. The methodologies and outcomes of the individual research projects are examined in greater detail below, by health impact.

 

Adverse Birth Outcomes

A large population-based study conducted by Brauer et al. (2008) examined the effects of exposure to urban air pollution on birth outcomes, using a birth cohort in Metro Vancouver. Researchers examined the impacts of individual-level intraurban exposures to air pollution on small for gestational age (SGA) birth weights, low full term birth weight (LBW) and preterm birth. Exposure to air pollution for each cohort member was assigned using both land use regression and monitoring methods (by nearest monitor and inverse distance weighting (IDW) approaches). The results of the studies indicated that an increased number of low full term birth weight and premature births was associated with poor air quality. Residing within 50m of highways was associated with a 26% increase in small for gestational age birth weight and an 11% increase in low full term birth weight. Small for gestational age births were associated with increased exposures to all pollutants except O₃. PM_2.5 was associated with preterm births for births less than 37 weeks of gestation (and for other pollutants at < 30 weeks). The results did not show specific exposure windows during pregnancy that were of greater or lesser relevance for SGA or preterm births.

Asthma

Although air pollution is known to be a factor that influences the severity of asthma and can trigger asthma symptoms, less is known about the role of air pollution in the development of this disease. A population-based study conducted by Clark et al (2010) investigated the effects of air pollution exposure in utero and during the first year of life on the risk of asthma diagnosis in children up to 3 and 4 years of age. Air pollution exposure for each subject at their home residence was estimated using monitoring data, land use regression and proximity to stationary pollutions sources.  Asthma diagnoses were identified through physician billing records and from hospital discharge records. The results of this study indicate that air pollution exposure in utero and during the first year of life may play a role in the development of childhood asthma. Asthmatic children had higher mean exposures for NO, NO₂, CO, PM₁₀, black carbon, SO₂ and points sources compared with non-asthmatic children. A statistically significantly increased risk of asthma diagnosis with early life exposure to CO, NO, NO₂, PM₁₀, SO₂, black carbon and proximity to point sources, was shown.  Traffic-related pollutants were associated with the highest risk of developing this disease.

Bronchiolitis

Another study investigated the role of ambient air pollution on infant bronchiolitis in the Georgia Basin Airshed (Karr et al, 2009). The population based cohort consisted of all singleton children born between 1999 and 2002 in the Georgia Basin Airshed.  Infants were defined as having bronchiolitis if they had a clinical encounter for bronchiolitis between the second and twelfth month of life. Exposure to traffic-related pollutants was measured using multiple methods including ambient monitors, traffic based land-use regression models and proximity to highways. The results from this study show that increased exposure to NO₂, NO, SO₂, CO, and increased woodsmoke exposure days, and point source emissions scores were associated with increased risk of bronchiolitis. These associations indicate that ambient air pollution may increase infant bronchiolitis requiring medical care, even at levels of pollution deemed safe by regulatory standards. 

Otitis Media

Otitis media is a middle ear infection, the most frequently diagnosed bacterial infection in young children and a leading cause for physician visits. As part of the Border Air Quality Study, researchers at the University of British Columbia evaluated the relationship between ambient air pollution and otitis media. All singleton children born in the Georgia Basin Airshed during 1999-2000 were followed until 2 years of age (MacIntyre et al, 2011). Residential air pollution exposures were estimated using monitoring data (CO, NO, NO₂, O₃ , PM_2.5, PM₁₀, SO₂), temporally adjusted land-use regression models (NO, NO₂, PM_2.5, black carbon, wood smoke), and proximity to roads and point sources. Results indicate that, of the 45,513 children (76% of all births between1999-2000), 42% had 1 or more physician otitis media during the 2 years follow-up period. Positive associations of otitis media with certain primary traffic emissions (NO) were observed. A strong association between residential wood smoke and otitis media was found. The results of this study show that, even in a region with relatively low levels of ambient air pollution, modest but consistent associations were found between certain air pollutants and otitis media in young children.

Adult Cardiovascular Diseases

Studies conducted by Gan et al. (2010, 2011) investigated the relationship between residential proximity to traffic and mortality from coronary heart disease (CHD). The population based cohort consisted of 414,793 residents of Metro Vancouver, Canada, between the ages of 45-85 years of age who had no previous diagnosis of CHD. Based on land use regression data, subjects who consistently lived close to traffic and those who both moved close to and away from traffic experienced elevated exposure to traffic-related air pollution (PM_2.5, NO₂, NO, and black carbon), in comparison to those that consistently lived away from traffic. Results also indicate that living close to traffic was associated with an increased risk of mortality from CHD while moving away from traffic was associated with a decreased risk. Long-term exposure to traffic-related fine particulate air pollution, indicated by black carbon, may partly explain the observed associations between exposure to road traffic and adverse cardiovascular outcomes. A major strength of this study included its ability to reduce exposure misclassification by accounting for residential relocation during the exposure period. Including detailed residential history information when determining exposure status in a large population based cohort allowed the observation of novel results.

14.1.2 Studies on Health Burden of Cancer-Related Impacts

A study on the cancer-related impacts of air quality completed by Levelton Engineering Ltd, Alchemy Consulting Inc. and Dr. D.V. Bates (2000) examined the associated environmental concerns, health risks and tradeoffs of diesel particulate matter in the Lower Fraser Valley of BC. This study used estimates made by the California Air Resources Board (CARB), which identified the cancer risk factor of continuous exposure to diesel particulate matter to be 300 cases of cancer per million individuals if a person was exposed to one ug/m³ of diesel particulate matter over a 70-year lifetime. Based on these estimates, it was identified that cancer risk from diesel particulate matter in the Lower Fraser Valley appeared to be a small component of the current total lifetime risk from cancer from other sources (about 200,000 to 250,000 in a million) over a 70-year period. The estimated 45 per cent decline in diesel particulate emissions from current levels, expected to occur by 2010-2015 as a result of air quality management measures, was projected to result in a potential reduction of cancer risk (Levelton Engineering et al., 2000).

A second air toxics study, conducted by the Puget Sound Clean Air Agency examined the potential health risk of a number of different air contaminants to residents of Puget Sound. This study revealed that the primary health effect of the chemicals was lung cancer, which was associated primarily with diesel soot. The study identified that, on average, diesel soot accounted for between 70 per cent and 85 per cent of the total cancer risk from air toxics in the Puget Sound area. Wood smoke, benzene, formaldehyde carbon tetrachloride and a number of other toxins were also seen to be contributing to cancer as illustrated in Table 14.1. In addition to lung cancer, the air toxins also contributed to leukemia, nasal and liver cancers. The average cancer risk for monitored air toxins in the greater Seattle/King Country area was identified as approximately 550 per million. Cancer risk was similar across the different areas monitored in Puget Sound (Keill and Maykut, 2003).

14.1.3 Studies on Health Burden of Non-Cancer Related Impacts

A paper produced for the South Fraser Health Region of BC in 2001 noted: “About as many deaths in the Lower Mainland may be attributable to air pollution as from HIV, accidental falls or traffic accidents” (South Fraser Health Region, 2001). A Health Canada study reviewing 10 years of data found that non-accidental death in Greater Vancouver increased by 8.3 per cent on high-pollution days (Burnett et al., 1998). Studies done in Greater Vancouver have found that, with a 25 per cent reduction in PM₁₀, more than 2,700 premature deaths and 33,000 emergency room visits could be avoided over a 30-year period (Nugent, 2002).

A study done by Jackson et al. (2010) examined projected excess deaths due to increase in ground-level ozone concentrations at mid-century (2045-2054) in King and Spokane counties in the Washington State. The overall and cardiopulmonary mortality was estimated using current (1997-2006) ozone measurements and mid-twenty-first century ozone projections, coupled with dose-response data from the scientific literature. Current daily maximum 8-hr ozone concentrations are forecasted to be 16-28% higher by 2045-2054. By mid-century in King County, the non-traumatic mortality rate related to ozone was projected to increase from baseline (0.026 per 100,000) to 0.033. The cardiopulmonary death rate per 100,000 due to ozone was estimated to increase from 0.011 to 0.015.

14.2 Socio-Economic Impacts of Poor Air Quality

In this chapter, the economic costs of air pollution are categorized under three broad components: health impacts, visibility impacts and environmental impacts. Broadly speaking, there are substantial costs attributed to health impacts. Reduced visibility may affect tourism revenues and enjoyment of natural scenery. Air pollution results in ecological impacts potentially leading to reduced crop yields and damages to natural ecosystems and related economic activities.

14.2.1 Health Related Impacts

Air pollution has a wide range of negative impacts on human health that range from increasing severity of asthma and breathing problems, emergency room visits and hospitalisations, as well as increased risk of premature death. A number of techniques are available to quantify the socio-economic value of these impacts. These methods generally focus on the total impact of poor health, as measured from a quality of life perspective. As such, these economic values will include both the costs associated with health problems, such as increased medical costs and reduced worker productivity, as well as quality of life impacts like increased pain and suffering, or increased mortality risk.

Models specifically designed for this analysis include the Illness Cost of Air Pollution (ICAP, Ontario Medical Association, 2008) or the Air Quality Benefits Assessment Tool (AQBAT) (Judek et al, 2006). These tools estimate the health and welfare benefits associated with improvements in ambient air quality by employing the “damage function approach”, a generally accepted method where a change in air quality is specified by the analyst and risk factors are employed to quantify the health and related outcomes.

On the local scale, a study conducted by Furberg and Preston (2005) in the Georgia Basin/Puget Sound airshed estimated that a 10% improvement in ground level ozone and particulate matter (PM_2.5) from a 5-year average baseline (1999-2003) concentration level would respectively provide an estimated C$24.8 and C$268.8 million (2003 dollars, undiscounted) in annual health and other related benefits within the Lower Fraser Valley (LFV) and Whatcom County area at year 2010. These monetized benefits are generally attributed to mortality outcomes (~80%) for both PM_2.5 and ozone. However, health events such as chronic bronchitis and minor restricted activity days also contribute significantly. Accounting for forecasted population growth within the region, these values are estimated to increase to C$27.7 and C$300.1 million for ozone and particulate matter, respectively, by year 2020.

 

14.2.2 Visibility Impacts

The Georgia Basin/Puget Sound region boasts spectacular pacific coastal areas, majestic mountains, and unique landscapes, attracting visitors from around the world. Throughout this region, tourism is a key economic factor. As many people visit the area to enjoy the spectacular vistas that the region has to offer, visibility impairment may obscure these vistas and negatively affect tourism.

A study conducted within the Pacific Northwest (Metro Vancouver and the Fraser Valley Regional District (FVRD) (McNeill and Roberge, 2000) concluded that reduced visibility resulting from air pollution may significantly impact regional tourism revenues. The study surveyed local area tourists evaluating their perception of poor visibility episodes. Survey participants were presented with a series of photographic images depicting visibility loss (represented by Bsp - a measure of light scattered by particles) and asked whether each scenario viewed (depicting different severity levels of compromised visibility) influenced their decision to recommend the region to others or to return for additional visits. 

Note: A higher Bsp indicates poorer visibility

 

For a single extreme visibility event assumed to occur during the peak tourist season, regional tourism revenue losses were estimated to be as high as C$7.45 million for the Vancouver area and C$1.32 million in the Fraser Valley. These estimates do not represent the annual mean tourist losses from visible air pollution, which in aggregate would be a larger figure. As the less extreme air quality events are more frequent, they may have a greater cumulative impact than the more extreme events. However, some limitations of the model should be acknowledged, including the use of simplifying assumptions with regards to tourist recruitment and the omission of dynamic considerations such as the timing and number of return visits, and long-term reputational consequences of persistent poor visibility (McNeill and Roberge, 2000).

Another study conducted in the Lower Mainland area employed stated preference contingent choice (CC) survey techniques to estimate dollar values individuals are willing to pay for improved visibility. The discrete choice experiment focused on three different attributes: visibility perception (based on a series of photographic images), health risk (based on the air quality index), and household cost (the preferred method of payment). The estimated welfare effects concluded that a 5% to 20% improvement in visual range was valued at C$29.38 to C$48.55 per household per year, respectively. These estimates represent the annual value that individual households were willing to pay for various levels of visibility improvements. The authors note that the values lie at the low range of studies conducted elsewhere (in U.S. cities), suggesting the low values may be because visibility in the study area is better than the levels observed in the other study areas (Haider et al., 2002).

Notes:

¹ change in visual range is based on an average daily visual range of 60 km for a 60 day summer season

² defined as a shift in days from “poor” to “excellent” visibility, which translates into an increase in the average daily visual range of 1.78 km (~3%)

 

Building upon the findings of this study, Environment Canada has developed a valuation module, which was integrated into the Air Quality Valuation Model (AQVM2), to estimate the monetary change in residential welfare due to a change in visual range. To this end, changes in visual range associated with different ambient levels of air pollution are translated into changes in the deciview scale, which is a visual index designed to be linear with respect to perceived visual changes over its entire range. The deciview scale is zero for pristine conditions and increases as visibility degrades. A decrease of 1 deciview roughly corresponds to a 10% improvement in visual range (in km), regardless of the initial visual range. Assuming the change in welfare is proportional to the change in the deciview scale, willingness-to-pay estimates for visibility improvement may be derived for Canadian households and used as indicative values for environmental policy analysis.

14.2.3 Environmental Impacts

Air pollution stresses natural ecosystems and impairs their capacity to provide ecological goods and services, which may further translate into economic losses for resource-based industries such as forestry, fishing and agriculture. Although the number of available studies focusing on the Georgia Basin/Puget Sound airshed may be limited, the economic value of these environmental impacts could nonetheless be significant.

Agriculture

Air pollution has direct impacts on agricultural production. Different pollutants, one of the most important being ozone, can affect plant processes that control or alter growth and reproduction, potentially increasing or decreasing agricultural yield. Elevated concentration of ground level ozone is the most significant air quality issue affecting agricultural production. Plant exposure to ground level ozone can result in visible foliar damage, altered carbohydrate allocation (resulting in reduced growth and yield), and alteration of competitive patterns within plant communities and ecosystems (Environment Canada and Health Canada, 1999; Guderian et al., 1985). The EPA reports that ozone exposure affects the physiological processes in plants, including reduction in photosynthesis and increased leaf senescence that can lead to a reduction in plant growth. Ozone exposure may also result in decreased nutrient uptake, competitive ability and reproductive efficiency, as well as increased foliar leaching and susceptibility to root disease, drought and windthrow (U.S. EPA, 2010b).

The Lower Mainland is an important food production area, with 27% of BC’s total gross farm receipts produced in Metro Vancouver (2006) on 1.5% of the provincial land-base (Metro Vancouver, 2009). Hence, the economic damages of agriculture loss associated with poor air quality are of concern at the regional level.

Research concludes that decreased concentrations of ozone during the summer season will result in improved yields for vegetables, berries and forage crops. A study conducted as part of a cost-benefit analysis of the Greater Vancouver Regional District’s (GVRD’s) initial Air Quality Management Plan estimated air quality impacts on seven different crops associated with implementation of the AQMP and the Vehicle Emissions Standards. The reported estimate of reduced crop damage in the Lower Fraser Valley (LFV) from implementation of the initial AQMP and the VES was C$3 million (1993 dollars) in year 2005 (ARA Consulting and BOVAR-Concord Environmental Consultants, 1994).

Based on biological exposure-response functions, Environment Canada developed a valuation module for AQVM2 to provide an indication of the impact of a change in ambient levels of ground-level summer ozone on the sales revenue of Canadian crops producers (Folkins, 2008). Changes in production (yields in tonnes) and expected sales revenue may be estimated for 19 types of crops.

Forest Ecosystems

Air pollution is also associated with damages to forest ecosystems. For instance, ozone exposure may generate visible foliar symptoms, reduction in tree growth and productivity, and increased vulnerability to pest attacks (Karnosky et al., 2007; Percy et al., 2009). These impacts may result in economic losses for the timber industry by diminishing timber yields or delaying the optimal time of harvest. In addition, the reduced timber volume may impair the capacity of forest ecosystems to store carbon (Wittig et al., 2009) and provide other valuable ecological services.

Water Ecosystems

Emissions of air pollutants, such as sulphur oxides and nitrogen oxides, may interact in the atmosphere to eventually form acid deposition, which contribute to water acidification or eutrophication. By favouring algal proliferation and cyanobacterial blooms, eutrophication may diminish recreational activities and tourism revenues around impacted lakes or streams, generate unpleasant odors and visual disamenities, threaten aquatic biodiversity, reduce property values and increase drinking water treatment costs (Dodds et al, 2009). By reducing fish population, lake and stream acidification or eutrophication may also adversely impact the recreational fishing industry.

Material Soiling

Material soiling is another recognized economic damage associated with air pollution. Materials are affected by airborne particles by soiling, erosion or corrosion of surfaces (Environment Canada and Health Canada, 1999). Although limited, the existing literature provides a range of estimates for quantifying the economic cost of material soiling. Based on these, AQVM2 may provide indicative values of avoided cleaning expenditures for residential households associated with a change in the ambient concentration of particulates (PM₁₀) (Chestnut et al., 1999).

14.3 Chapter Summary

Poor air quality affects human health, economic activity and diminishes the quality of life for residents. In the Georgia Basin/Puget Sound airshed, current levels of air pollution have been found to have measurable health impacts. Through the Border Air Quality Strategy, novel research projects specific to the Georgia Basin/Puget Sound airshed have provided an increased understanding of the associations between increased exposure to air pollutants and increased risk of adverse birth outcomes, childhood respiratory disease and adult cardiovascular disease. Results from these studies highlighted the opportunity for reducing adverse health outcomes through consideration of traffic and proximity to highways during urban planning, as well as strategies to reduce residential wood combustion emissions. In addition to health impacts, there exist economic consequences stemming from pollution, which may impact agriculture, visibility, recreational welfare and the overall condition of natural ecosystems.

14.4 References

ARA Consulting Group Inc. and BOVAR-Concord Environmental Consultants, 1994. “Clean Air Benefits and Costs in the GVRD”. Prepared for Greater Vancouver Regional District, B.C. Ministry of Environment, Lands & Parks and Environment Canada. (Draft report - issued unchanged as final in Nov/1995).

Bates, D.V. and Caton, R.B., eds., 2002. “A Citizen’s Guide to Air Pollution, second edition”, The David Suzuki Foundation, Vancouver, B.C.

Bates, D.V., Koenig, J. and Brauer, M., 2003. “Health and Air Quality 2002 - Phase 1 Methods for Estimating and Applying Relationships Between Air Pollution and Health Effects”, pp.105.

Brauer, M., Lencar, C., Tamuric, L., Koehoorn, M., Delmers, P. and Karr, C., 2008. “A Cohort Study of Traffic-Related Air Pollution Impacts on Birth Outcomes”. Environmental Health Perspectives 116, 680-686.

British Columbia Lung Association, 2009. “Outdoor Air Quality. A Primer for B.C. Physicians and Resource for Informing Patients”.

Burnett, R., Cakman, S. and Brook, J., 1998. “The Effect of the Urban Ambient Air Pollution Mix on Daily Mortality Rates in 11 Canadian Cities.” Canadian Journal of Public Health, Vol. 89.

Chestnut, L., Mills, D., and Rowe, R., 1999. “Air Quality Valuation Model Version 3.0, Report 2: Methodology, Final Report”.  Stratus Consulting Inc, Scientific Authorities: Paul De Civita-Environment Canada, David Stieb-Health Canada, (Sept/99). 

Clark, N., Demers, P., Karr, C., Koehoorn, M., Lencar, C. Tamburic, L. and Brauer, M., 2010. “Effects of Early Life Exposure to Air Pollution on Development of Childhood Asthma”. Environmental Health Perspectives 118, 284-290.

Dockery, D.W., Damokosh,  A.I., Cunningham, J., Neas, L.M., Spengler, J.D., Koutrakis, P., Ware, J.H.,Speizer, F.E. and Raizenne, M., 1996. “Health effects of acid aerosols on North American children: respiratory symptoms”. Environmental Health Perspectives 104, 500-505.

Dodds, W.K., Bouska, W.W., Eitzmann, J.L., Pilger, T.J., Pitts, K.L., Riley, A.J., Schloesser, J.T. and Thornbrugh, D.J. 2009. “Eutrophication of U.S. Freshwaters: Analysis of Potential Economic Damages”. Environmental Science & Technology 43 (1), 12-19.

Environment Canada and Health Canada, 1999. “National Ambient Air Quality Objectives for Ground Level Ozone (Part 1: Science Assessment Document - A Report by the Federal-Provincial Working Group on Air Quality Objectives and Guidelines”. 

Folkins, T., 2008. “Benefits Assessment of Policy Induced Reductions of Tropospheric Ozone Levels to Canadian Crop Production”. Draft, Economic Analysis Directorate, Environment Canada, Gatineau, Canada.

Fraser Basin Council, 2003. “A Snapshot of Sustainability: State of the Fraser Basin Report”.

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.

Gan, W., Tamburic, L., Davies, H., Demers, P., Koehoor, M. and Brauer. M., 2010.  “Changes in Residential Proximity to Road Traffic and the Risk of Death from Coronary Heart Disease”. Epidemiology 21 (5).

Gan, W., Koehoor, M., Davies, H., Demers, P., Tamburic, L. and Brauer. M., 2011.  “Long-term exposure to traffic-related air pollution and the risk of coronary heart disease hospitalization and mortality”. Environmental Health Perspectives 119 (4), 501-507.

Guderian, R., Tingey, D.T. and Rabe, R., 1985. “Effects of Photochemical Oxidants on Plants”. In Air Pollution by Photochemical Oxidants - Formation, Transport, Control and Effects on Plants. Edited by R. Guderian. Residue Reviews 52, 129 - 346. Springer-Verlag, Berlin Heiderberg.

Haider, W., Moore, J., Knowler, D. and Anderson, D., 2002. “Estimating Visibility Aesthetics Damages for AQVM (Final Report)”. Prepared for Environment Canada - Environmental Economics Branch, Aug/02.

Judek, S., Stieb, D. and Jovic, B., 2006. “Air Quality Benefits Assessment Tool (AQBAT) release 1.0”.

Jackson, J., Yost, M., Karr, C., Fitzpatrick, C., Lamb, B., Chung, S., Chen, J, Avise, J., Rosenblatt, R. and Fenske, R., 2010. “Public health impacts of climate change in Washington State: projected mortality risks due to heat events and air pollution”. Climate Change 102, 159-186.

Karnosky, D.F., Skelly, J.M., Percy K.E. and Chappelka, A.H. 2007. “Perspectives regarding 50 years of research on effects of tropospheric ozone air pollution on US forests”. Environmental Pollution 147, 489-506.

Karr, C., Demers, P., Koehoorn, M., Lencar, C., Tamburic, L. and Brauer, M., 2009. “Influence of Ambient Air Pollutant sources on Clinical Encounters for Infant Bronchiolitis”. American journal of Critical Care in Medicine 180, 995-1011.

Keill, L. and Maykut, N., 2003. “Final Report: Puget Sound Air Toxics Evaluation.” Puget Sound Clean Air Agency in conjunction with Washington State Department of Ecology.

Legator, M.S., Singleton, C., Morris, D., and Philips, D., 2001. “Health Effects from Chronic Low-Level Exposure to Hydrogen Sulfide”. Archives of Environmental Health 56 (2), 123-131.

Levelton Engineering Ltd., Alchemy Consulting Inc. and Bates, D.V., 2000. “Diesel Particulate Matter and Associated Environmental Concerns, Health Risks and Tradeoffs”. Report prepared for the On Road Diesel Emissions Evaluation Task Force. Project 499-0998.

MacIntyre, E., Karr, C., Koehoorn, M., Demers, P.A., Tamburic, L., Lencar., C. and Brauer, M., 2011. “Residential air pollution and otitis media during the first two years of life”. Epidemiology 22 (1), 81-89.

McNeill, R. and Roberge, A., 2000. “The Impact of Visual Air Quality on Tourism Revenues in Greater Vancouver and the Lower Fraser Valley”. Environment Canada, Georgia Basin Ecosystem Initiative, Vancouver, BC.

Metro Vancouver, 2009. “Regional Growth Strategy Review Backgrounder #11: Agriculture and the Regional Growth Strategy”.

National Park Service Website, U.S. Department of the Interior

Nugent, O., 2002. “The Smog Primer”. Pollution Probe. June, p.22.

Ontario Medical Association, 2008. “Illness Costs of Air Pollution Model (ICAP)” developed by DSS Management Consultants Inc for Ontario Medical Association.

Partti-Pellinen, K., Marttila, O., Vilkka, V., Jaakkola, J.J.K., Jappinen, P. and Haahtela, T. 1996. “South Karelia air pollution study: Effects of low-level exposure to malodorous sulfur compounds on symptoms”. Environmental Health 51 (4), 315-320.

Percy, K.E., Nosal, M., Heilman, W., Dann, T., Sober, J. and Karnosky, D.F. 2009. “Ozone exposure-based growth response models for trembling aspen and white birch”. In A.H. Legge (editor), Air quality and ecological impacts: relating sources to effects, Developments in Environmental Science, volume 9. Oxford, United Kingdom, 269-293.

Raizenne, M, Neas, L.M., Damokosh, AI, Dockery, D.W., Spengler, J.D., Koutrakis, P., Ware, J.H. and Speizer, F.E., 1996. “Health effects of acid aerosols on North American children: Pulmonary function”. Environmental Health Perspectives 104, 506-514.

South Fraser Health Region, 2001. “Air Quality in the Lower Mainland: Patterns, Trends and Human Health, South Fraser Health Region”. South Fraser Health Region.

U.S. EPA (Environmental Protection Agency), 2002. “Health Assessment Document for Diesel Engine Exhaust”. National Center for Environmental Assessment - Office of Research and Development. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (Environmental Protection Agency), 2006. “Air Quality Criteria for Ozone and Related Photochemical Oxidants”. Volume I. National Center for Environmental Assessment - Office of Research and Development. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (Environmental Protection Agency), 2008a. “Integrated Science Assessment for Sulfur Oxides - Health Criteria”. National Center for Environmental Assessment - Office of Research and Development. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (U.S. Environmental Protection Agency), 2008b. “Integrated Science Assessment for Oxides of Nitrogen - Health Criteria”. National Center for Environmental Assessment - Office of Research and Development. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (Environmental Protection Agency), 2009. “Integrated Science Assessment for Particulate Matter”. National Center for Environmental Assessment - RTP Division. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (Environmental Protection Agency), 2010a. “Integrated Science Assessment for Carbon Monoxide”. National Center for Environmental Assessment - RTP Division. U.S. Environmental Protection Agency. Washington, DC.

U.S. EPA (Environmental Protection Agency), 2010b. “Chapter 2: Effects of Air Pollutants on Ecological Resources (A Literature Review)”. Second Section 812 Prospective Analysis Ecological Report - Draft February 2010.

U.S. EPA (Environmental Protection Agency), 2012a. “Health Effects - Particulate matter”.

U.S. EPA (Environmental Protection Agency), 2012b. “Health Effects - Ground level ozone”.

U.S. EPA (Environmental Protection Agency), 2012c. “Health Effects - Sulfur dioxide”.

U.S. EPA (Environmental Protection Agency), 2012d. “Health Effects - Nitrogen dioxide”.

Wittig, V.E., Ainsworth, E.A., Naidu, S.L., Karnosky, D.F. and Long, S.P. 2009. “Quantifying the impact of current and future tropospheric ozone on tree biomass, growth, physiology and biochemistry: a quantitative meta-analysis”. Global Change Biology 15, 396-424.

Wyzga, R.E. and Folinsbee, L.J. 1995. “Health Effects of Acid Aerosols”. Water, Air and Soil Pollution 85, 177-188.

 

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