1a
1) Global climate change
a) The aggregate health burden related to global climate change represents among the most consequential environmental health challenges of our generation. Multiple direct and indirect pathways of adverse impact have been discussed and debated within the current scientific literature. Provide examples of a specific environmental health effects linked to climate change that may be mediated via: 1) chemical; 2) infectious disease; and 3) psychosocial risk factors.
Chemical
Chemical pollution is a problem in many parts of the world today. It can be expected to become worse under conditions of changing climate for several reasons. First, changing climate and weather conditions are likely to impact several air pollutants (Patz, 2005; Confalonieri et al. 2007). The formation of tropospheric ozone is closely related to energy input in the form of heat (Patz, 2005). Exposure to ozone is associated with acute effects on respiratory function as well as long-term impacts such as chronic obstructive pulmonary disorder (COPD) and mortality (Bell, et al 2004; Bell & Samet, 2005). A warming climate is expected to increase the duration of ozone seasonality as well as concentrations in general (Chen, et al 2004). Moreover, behavioral responses to warmer weather such as spending more time outdoors can increase exposure to ozone (Levy, et al. 2001).
Chemical hazards through exposures to water can also be affected by a changing climate. Pollution in many urban areas enters waterways via runoff. Climate change is expected to introduce greater variability in the climate, including more extreme weather events such as floods and droughts. In the case of floods this may wash urban pollution into homes. Increased water volumes may overwhelm treatment facilities and result in the release of contaminated water in the environment. In droughts there will be increased scarcity of freshwater resources. As water resources decrease the concentrations of pollution in the water increase. Thus ingestion of water under drought conditions results in larger doses of pollution. With less water the doses of ingested pollution from drinking contaminated water increase. Similarly, exposure to contaminated sources will also increase in the face of scarcity, particularly in locations without piped supply. In such settings, people may be forced to gather more frequently and closer to urban sources.
Finally, chemical exposures may also increase as climate changes. Warmer climates and increased CO2 fertilization is expected to increase the growing season and yield of vegetation in many parts of the world (Dufresne et al. 2002). Changes in the climate are expected to affect different regions and varieties of plants differently. It has been found that one of the most responsive plants to changes in CO2 concentrations in poison ivy (Ziska et al. 2009). Herbicides may become more widely used as nuisance vegetation in a region becomes more productive. Additionally, the spread of pests to crops and gardens may also change as new areas become hospitable for insects. These changes may increase the use of pesticides and thus personal chemical exposures.
Infectious Disease
Similar to the example that described changing water pollutant concentrations, fluctuations in water supplies and precipitation events can have effects on the spread of infectious disease. This occurs in several ways. First, bodies of water will be more likely to contain waterborne infectious diseases, such as cholera or cryptosporidium, if fewer sources exist and are used by people in endemic areas. Similarly, fewer freshwater sources in an area will make those sources more intensely used for drinking water and for activities such as bathing and washing clothes. Second, increased precipitation in some areas will sustain pooling and provide more breeding grounds for vectors such as mosquitos. This is particularly important for urban areas where debris and trash act as receptacles for water near homes. They, in turn, serve as breeding grounds for the A. Egypti mosquito, which transmits Dengue Fever. Third, drought can also increase pooling by reducing normally flowing rivers and streams to dry beds with stagnant pools (McMichael et al. 2003).
The expected changes in temperature throughout the planet are also expected to increase vector habitats. A commonly cited example of this is the movement of malaria-carrying mosquitoes to higher elevations. Settlements have developed at elevations that were previously sufficient to avoid the malaria-carrying Anopheles mosquito. As temperatures increase, elevated temperatures at higher elevations cease to protect the settlements and previously unexposed populations become hosts for the disease. Shorter and milder winters can also allow insect vectors to migrate into previously inhospitable areas and encounter populations with little immunity, technology, or cultural practices to protect themselves (Patz et al. 1996). Temperature increases also speed up the life cycle of the infectious agents in many vector borne diseases. Changes to these extrinsic (outside of the human but inside of the vector) incubation periods can increase the transmission dynamics of the infectious disease (Focks, et al. 1993). Finally, changes in climate affect the behavior of the vectors themselves. Elevated temperatures cause some vectors to increase their biting rates and thus to increase the transmission rate of the infectious diseases they carry.
The human behavioral response to climate change may also increase exposures to infectious diseases and vectors that carry disease. As already discussed, drier climates may force people to more intensely use limited water sources. Further consideration of this prospect suggests that hotter weather may increase water use for relief from the heat (i.e. more frequent swimming). This will likely involve exposed skin to water as well as submersion and ingestion of water, perhaps facilitating larger doses of infectious agents. Warmer weather in many parts of the world may also increase time spent outside and in vector habitat. Additionally, people may respond to warmer temperatures and longer summers by spending more time in clothes that expose skin. Finally higher daytime temperatures may lead to the rescheduling and relocating of many events to outdoor locations in the early evening. Such responses to climate change can act to increase human exposures to insect vectors and facilitate the transmission of vector-borne disease.
Psychosocial
The issue of climate change is already a significant source of stress for people around the world. The thought of diminishing water supplies, rising seas levels, and more frequent storms can result in significant time and energy spent to avoid future property damage and personal harm. These concerns can lead to depression and social isolation. Stress is also a risk factor for chronic disorders, childhood development (Schwartz, 1985) and even for biological responses to environmental toxics (Gee & Payne-Sturges, 2004). Particularly for regions and populations susceptible to significant changes with global climate change stress is expected to increase. This includes populations of island nations and coastal areas susceptible to sea level rise, areas vulnerable to extreme storms, and populations already facing pressures on water and food systems. Climate change may increase the pressure on such systems and force populations to leave their homes and migrate. Alternatively, increasing pressures on food and water supplies may also result in conflict. Fighting for land, water, and food will not only result in more stress, but in casualties and many indirect effects. These include nonfatal injuries, post-war stress disorders, the destruction of infrastructure, and the contamination of land with weapons and hazardous waste (Levy & Sidel, 2005). Such effects can have positive feedbacks on stress levels for associated populations.
Stress also reduces the capability of populations to adapt and respond to climate change, which can exacerbate negative health outcomes. Communities facing a number of environmental stressors, or responding and rebuilding after an extreme weather event have less resources and time to contribute toward preparing for the next. Thus there are feedbacks for psychosocial stress and adaptive capacity that are compounded as the effects of climate change hit a population. Similarly climate change’s distributional effects on population may affect adaptive capacity directly by breaking apart social support networks in communities. Thus climate change can be expected to not only increase stress for populations but also affect their ability to deal with climate change (Smit & Wandel, 2006).
Social isolation can also be a risk factor for climate-related health effects. For example limited interaction with public may isolate people from public health messages related to adaptation measures and emergency response. Additionally, living alone has been shown to be a risk factor for heat-related mortality. Conversely, increased social contact has been shown to be protective (Bouchama et al. 2007).
1b
1) Global climate change
b) Climate change and urban sprawl, in particular, are two critical environmental health challenges that are fundamentally connected. Explain the key linkages and discuss potential solutions to each of these challenges.
Sprawl has a direct impact on climate change in two key ways. Here I provide a description of these two linkages, followed by a discussion of the role of sprawl in modifying climate change mitigation and adaptation efforts. Finally the possibilities of cobenefits and interactions are explored.
Sprawl’s Connections to Climate Change
First, sprawl is a driver of climate change through the emission of greenhouse gases (GHG). Sprawling development patterns foster lifestyles that are incredibly resource-dependent and thus responsible for GHG emissions. Sprawl is associated with increase personal vehicle usage with respect to number of trips, length of trip, and average vehicle miles traveled per person. Thus it is a driver of fuel consumption and of emissions, including carbon dioxide. Sprawl also encourages the development of larger buildings that are separated from one another. This drives emissions in two ways. First, larger buildings require more energy to power, heat, and cool; second, separated buildings lose and gain more heat through exterior surfaces than shared spaces and so they use energy less efficiently. Another important characteristic of sprawl that contributes to GHG emissions involves the development of land. Sprawl preferentially develops previously undeveloped greenfields and consequently contributes to conversion of land from natural land covers to development. In many areas this displaces farms or results in deforestation (Meyer & Turner, 1992). This results in the release of GHG from soils and the biomass itself as it is burned. Sprawl’s land use patterns demand and rely on goods being shipped over long distances to get from their place of production to market. Thus, supplying food and other goods to sprawling communities also results in significant GHG emissions. For these reasons, actions that counteract these tendencies of sprawling communities are seen as beneficial to mitigating climate change.
Climate change mitigation strategies related to sprawling patterns focus on reducing energy consumption by modifying technologies, changing behavior, or doing both. In buildings this includes installing high efficiency appliances, improving building insulation, and using local or recycled materials in construction. For transportation, solutions include incentive programs to encourage biking, walking, carpooling and telecommuting, increased shipping of materials by rail, improved transit, and increasing the availability of local foods. Finally land use strategies aim to preserve undeveloped land and encourage mixed land use patterns.
A second key connection between sprawl and climate change relates to local climate modification. This is exemplified by the urban heat island with elevated temperatures in developed areas when compared to surrounding rural areas. It is caused by the conversion of natural covers to materials that absorb more of the sun’s energy, by reducing evaporative cooling effects through the removal of local vegetation, and from the production and concentration of waste heat emissions (Taha 1997). Sprawling development patterns result in more conversion of land and removal of vegetation, particularly on a per capita basis. Localized warming in cities has been shown to be increasing faster than warming in surrounding rural stations and attributed to global climate change. The more rapid warming in cities is attributed to the urban heat island (Stone, 2007). With respect to public health concerns regarding changing climate and heat stress, more sprawling cities have exhibited a larger increase in extreme heat events in the past 40 years (Stone et al. 2010). Strategies to mitigate these direct impacts include increasing the reflectance of building materials, preserving urban vegetation, planting new trees, and reducing waste heat emission in the city (Stone, 2006).
Sprawl as a Modifier of Mitigation and Adaptation
Aside from the direct influences of sprawl on climate change there are several roles that sprawl plays in a community’s ability to mitigate and adapt to climate change. It is worth pointing out that actions taken to mitigate GHG emissions may be less effective in sprawling cities. As an example, consider the impact of investment in transit to offset personal automobile use for a region. In a compact, dense settlement the transit will likely to be able to serve many places that people both live and work, and thus replace several car trips. However, in a sprawling city, a similar transit investment will not be in close proximity to the same number of homes and destinations because people and business are more spread out across the region. In the sprawling community, the investment in transit will have less of an effect on reducing automobile travel and thus on mitigating GHG emissions. Similarly, the implementation of new renewable technologies, such as investment in wind energy, will not go as far in a sprawling community where energy use per household is likely higher than in denser cities with smaller homes. Strategies taken to mitigate the urban heat island, such as tree canopy preservation may also be less effective in locations where sprawl has already removed larger portions of natural tree cover.
The amount of sprawl in a region can also affect how the region will adapt to changing climatic conditions. Consider, for example, areas where more frequent and severe droughts are expected. The region is likely to address per capita demand by focusing on water efficiency in buildings – homes in particular. In sprawling communities, these adaptation strategies may represent bigger reductions for the area. However, in compact areas these low hanging fruit may not exist and adapting to water shortages may require larger investments. Conversely, adaptation strategies may focus on reducing impervious cover, decreasing runoff, and increasing infiltration and retainment of stormwater. Sprawling communities may find such strategies difficult to implement because of the necessity for parking lots. Finally, public health planning adaptation strategies for extreme weather events are likely to be more effective in less sprawling locations. Education messages, health services, and emergency plans can be disseminated more efficiently in denser agglomerations (Galea & Vlahov, 2005).
Cobenefits
Given the connections between sprawl and climate change, it should not be surprising that many of the strategies employed to mitigate climate change through the built environment have advantages to both sprawl and climate change. Transportation strategies that reduce GHG emissions by reducing vehicle use have several benefits for community health. Among the most direct are the associated reductions in the other air pollutants produced by automobiles such as carbon monoxide and particulate matter. Health benefits from increased physical activity can also be expected if reduced vehicle trips are replaced by trips made by walking, biking, or walking to transit. Similarly, land use strategies that result in reduced automobile trips would produce the same health benefits. Additionally, reduced driving would be expected to reduce stress and result in fewer traffic-related injuries (Younger, et al. 2008). Land use may also foster social capital in communities as interactions among people on the streets and in neighborhood ‘third places’ increase (Oldenburg & Brissett, 1982). As described above (1a psychosocial) these informal networks may be important for adaptive capacity in the face of climate change (Smit & Wandel, 2006). Street landscaping could be employed to mitigate urban heat island effects as well as encourage walking trips by increasing perceived safety. Parks can be used for similar heat island mitigation properties, and to provide stress-relieving exposure to nature (Frumkin, 2005). Building technologies to increase solar reflectance can also reduce energy use (Rosenfeld et al. 1998).
Continued sprawl will have impacts on the drivers of climate change as well as our ability to deal with it in the future. In some cases, sprawl also overlaps with the effects of climate change on infectious disease and can be considered a risk factor. For example, in new sprawling developments that coincide with the changing habitats of Lyme disease vectors. Given the influence of climate change on human health, number of people living in sprawling conditions in the US, the interactions and dependencies of sprawl and climate change are an important area for further study.
2a
2) Environmental Risk Assessment, Risk Perception, and Risk Communication
You have been approached by community members from a rural Appalachian town about the presence of a local cancer cluster. The community feels that the cluster is related to emission from a nearby factory of the chemical hydrogen x-factor (H2X) from its stack.
a) Using the environmental risk assessment paradigm of characterizing risk, describe the specific steps, at the various stages of this paradigm, you would take to determine the likelihood of the community’s concerns and characterize the risk of exposure to H2X.
Environmental Health Risk Assessment
Understanding and quantifying the risks that chemical exposures pose to populations is an important part of the environmental health profession. The risk assessment paradigm now familiar to environmental health professionals was born out of a 1983 National Research Council Report referred to as the Red Book. It was produced at a time when the US Environmental Protection Agency (USEPA) and other federal agencies were confronting issues of personal exposure to chemicals and attempting to link science and policy for the protection of human health (Omenn, GS 2003). It formalizes risk assessment as comprised of four steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Below I describe the approach in each of these steps for addressing the concerns of the Appalachian community related to the chemical H2X.
Hazard Identification
The purpose of this first step of risk assessment concerns identifying the basis for risk to be assumed. In our case, to justify the risk assessment by providing the evidence for a plausible association between the pollution and the health effects. The first step in hazard identification will be to collect data related to the agent of interest and the potential health effects. In this case the community has specified the chemical agent of interest as hydrogen x-factor (H2X). A common starting point for such inquires is the Agency for Toxic Substances and Disease Registry’s (ATSDR) ToxProfiles. This resource will provide detailed information regarding many chemicals and their potential harm to humans. There is the potential that H2X is not included in the ToxProfiles database. A second resource will be the Materials Safety Data Sheet (MSDS) for the chemical. The company will possess these documents, which detail the chemical properties of H2X and the uses in the facility. Toxic Release Inventories (TRI) could also be procured to estimate the amount of H2X released by the facility, as well as to identify other proximate point sources for the chemical. Characteristics of the chemical’s behavior in the environment can also be considered and investigated here. The agents’ role in photochemistry may be important for determining if other hazardous agents are related and need to be investigated. For example, the role of H2X in secondary pollutant formation may be important for understanding how its release ultimately results in a hazard for surrounding communities. Similarly, information on the use or presence of H2X within chemical mixtures would be an important to identify possible synergistic interactions between H2X and other chemicals. These interactions can increase the toxicity of compounds and exacerbate health outcomes.
The second step of hazard identification specifies the health effects linked to the chemical. Again the ToxProfiles will serve as an important resource. These may contain data from controlled exposures studies and animal experimental studies. Another resource for health effects data is the USEPA’s Integrated Risk Information System (IRIS), which is designed to connect health professionals to quality data on substance-related health effects. IRIS is intended to inform and direct risk assessment in a consistent way across settings and substances. A review of the literature would also be done to collect epidemiological studies related to H2X. These studies will be helpful in identifying vulnerabilities and disparities among affected populations. These may also elucidate risk and protective factors, but are likely not as useful for estimating effect size. The community has specified cancer as a health outcome of interest, but I would not limit this step to only cancer outcomes. While the potential cancer cluster has piqued the community’s attention, the health effects may go beyond this manifestation. Other health effects related to the chemical could include low infant birth weights, infant mortality, and decreased respiratory function.
Both of these steps will help further explain the expected pathways between the agent and effect. The literature on both the chemical and related health effects should help us to understand the primary pathways for exposure. These should not be limited to inhalation alone. If H2X is among in the USEPAs Hazardous Air Pollutants (HAPs) it may be that the chemical exhibits toxicity through ingestion of food and water, despite being originally characterized as airborne. This information will be important for informing the exposure assessment portion of the risk assessment.
Dose-Response Assessment
The dose-response assessment involves describing the relationship between exposure and disease. This involves selecting a model to represent the relationship for each agent-effect combination. These models will be important for estimating the response of individuals or populations to exposures that differ from those used in the studies identified in the previous step. For simplicity I assume the results of hazard identification only concern the impacts of H2X (without mixture interactions) through a single exposure mechanism (inhalation). Separate models could be developed based on mixture properties, differences in the population, exposure medium, and disease outcome provided ample data availability. In many cases assumptions must be made based on the data collected in the hazard identification step. The multistage linearized model will be used to model the dose-response relationship. The model is commonly used with cancer outcomes (Bartell, 2005 p.943). It assumes increasing cancer risk for each increase in dose. If benchmark doses (BMD) can be identified for H2X, these will be used to estimate the response for doses between these validated dose-response values. If the literature from hazard identification specifies that there is no cancer risk below a specific dose than a threshold model will be used. This step may be a considerable source of uncertainty in the final risk characterization due to insufficient data from laboratory studies describing the dose-response relationship.
Exposure Assessment
Exposure assessment seeks to accurately describe how the agents come into contact with humans. This includes describing the pollutant concentrations experienced by humans and may include specification of variations in exposures with regard to time, place and behaviors. Exposure assessment focuses on the individual as the target of exposures as opposed to using estimates of concentrations from pollution sources or concentration estimates from centralized monitors (Fenske, 2010; Ott, 1995). This distinction may be important for the Appalachian cancer cluster. Consider, for example, using the estimated release quantities from the TRI reports as a proxy for exposure for this population. Factors such as the stack height and seasonal meteorology will affect this estimate. More important, however, is the fact that these estimates may not reflect the actual exposure to concentrations experienced by individuals. Moreover, because personal exposure may vary by age, gender, and location, care should be taken to accurately reflect these differences in our final risk estimations.
Information from hazard identification will be used to specify the plausible routes and target populations for exposure estimation. For the sake of this example, I assume that the exposure route is limited to inhalation and the population includes all individuals in the community of concern. To assess the exposure of residents in this community I propose the use of personal air sampling monitors. Personal air sampling units can be worn by individuals to obtain a more accurate estimate of individual exposures. Total exposure over given time period is facilitated by passive sampling using reactive media. Continuous concentration information may be collected using more sophisticated equipment; however, given our preliminary interest in cancer health outcomes, as opposed to more acute effects, I propose using a daily estimate of total exposure. It must also be verified that daily exposures estimates are suitable for use with the dose-response models described above. It is a possibility that sampling badges for H2X do not exist, in which case a proxy gas may be used. Validation of this assumption would require ambient sampling of H2X and the proxy gas to show their correlation in the environment. A second reason to conduct ambient modeling would be to verify that concentrations of H2X vary as the emissions from the stack. Ambient H2X monitoring in the community could be compared to plant monitoring at the stack. This could help to implicate emissions from the facility in exposures in the community, as opposed to other sources of H2X. The sampling approach is designed to account for differences in exposure by location, gender, and age, but does not include information relevant to calculating the actual dose. Further study could include activity diaries to estimate level of exertion and resultant respiratory rates. In this study we will use published rates for groups of the population to arrive at expected dose.
With regard to sampling strategy, the community will be organized into four spatially defined sections and sample 5% of the households in each quadrant. Four equal area quadrants will be designated using a path from the stack to the centroid of the community and its orthogonal compliment (Figure 1). The size of the quadrants will be determined to cover the entire community. Households will be labeled using a NW to SE numbering system with in the quadrant and be selected using interval sampling. A starting household will be selected randomly from each quadrant. Individuals in sampled households will be asked to wear passive sampling badges for one week in each of four seasons. It is anticipated the dose-response relationships for cancer outcomes may be based on annual exposures and thus seasonal variations due to weather, and facility operation will be reflected. It is hoped that the population sample will include individuals of all ages. Additional purposive sampling will be done as needed.
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| Figure 1. Sampling Strategy (not to scale) |
For comparison, four communities will be identified and used for similar personal air monitoring. These communities will be proximate to the community in question but no more than 50 miles from the community itself and no more than 100 miles from the facility stack. Two households will be selected randomly in each of the comparison communities. Here again, activity diaries would be useful to determine the influence of personal behaviors on exposure differences and thus differences in risk. Instead of the timely and often misused diaries, we will in-depth interviews conducted at one home in each community/quadrant to identify differences in behavior patterns.
Risk Characterization
In the final step of the assessment the data previously collected is used to explain the risk of the population of interest. The previous steps of the risk assessment are intended to investigate evidence of the assumed risk. The steps give us reason to conduct the assessment, estimate the expected health response to different doses of the chemical agent, and investigate the actual exposure of humans to the agent of concern, respectively. In the final step, the results of the three proceeding steps are used to determine the risk to the population. Here we will combine the doses from the exposure assessment by gender, age and location, with the dose-response model selected earlier. From this we arrive at an estimate of risk for different sectors of the population. Similarly probability of risk can be calculated for our comparison cases. It is often useful to compare the risks of similar individuals in each community and present a relative or excess risk, which we can easily create from the output of our dose-response model.
Another consideration of our risk assessment deals with the timing of our exposures assessment and desire of community members for information on the risks they face. While our exposure assessment requires several seasons of data to accurately assess changes in exposure, we can produce preliminary risk estimates following the first season of sample. These results will be partial assessments of total risk, but early and frequent information exchange between the assessors and the community will help to build trust and may reduce risk perceptions.
Disclosure and explanation of uncertainties is a key component of the risk characterization. Risk characterization is thought of as a qualitative component to what is often seen as a wholly quantitative exercise (Omenn, 2003). Reflecting on the quality of the data collected in the previous steps helps to interpret the final estimations of risk and gives some idea of their validity. This includes examining the specific assumptions used in underlying studies listed in the ToxProfiles and in identifying BMDs. Uncertainty analyses will also be performed to provide a range of reasonable risk estimates rather than a single number. Interval analysis will be used to compare our initial risk estimates with a complimentary estimate calculated using more general estimates of exposure or a different dose-response model. In this way the interval analysis will demonstrate the sensitivity of risk estimates to uncertainties in the data, and may strengthen the case for our best-case (initial) calculations of risk.
Considering this, a key component of this risk assessment will be to describe the uncertainties and steps taken to account for them in each stage of the risk analysis. Several such steps are included in the design of the assessment. In hazard identification I mentioned the importance of looking for studies of various types to provide a strong evidence base for the agent-disease relationship and thus for demonstrable risk. I also mentioned considering the multiple pathways for exposure and possible interactions with other chemicals. A thorough examination of these possibilities will reduce uncertainty around the specific relationship of interest later. In the dose-response assessment I only mentioned two possible models; however, the multistage linear model is widely used with cancer outcomes. Several other models exist and these options can be explored further once the dose-response data for H2X is obtained. Nonetheless, many methods have considerable uncertainty for doses below the lowest observed BMD. In the risk characterization the lowest observed effect levels for studies will be reported. These are listed with the details of studies in ATSDR’s ToxProfiles. Regardless, the application of animal study data to human models is a concerning source of uncertainty in environmental health risk assessment. Finally, in the exposure assessment we have designed a detailed and extensive evaluation of personal exposure to reduce uncertainty in our estimation of exposure. This includes personal sampling with variety in season, location, gender, and age. We hope that our dose-response models have sufficient data to complement our specificity in exposure, but these exposure estimates can be still evaluated in terms of risks using comparative runs of a single dose-response model. In this way, detailed exposure assessment allows us to compare risks within the community. Despite these precautions, the degree of uncertainty in the final characterization will be strongly influenced by the amount and quality of information that exists on H2X.
2b
2) Environmental Risk Assessment, Risk Perception, and Risk Communication
b) Assume that the results from your risk assessment indicate minimal excess cancer risk associated with exposure to H2X. Research in risk perception has found low correlations between the degree of true physical risk and the amount of worry that it arouses. Discuss a distinct barrier to effective risk communication. Name two principles you might use when communicating the risk of H2X to the community?
Risk Communication
The uncertainty described in the risk characterization is likely to produce results that do not explain risk as exact answers to the original questions raised by the community. This uncertainty can make the public skeptical of any policy decision to come out of the risk assessment. Entering the public realm with decisions of uncertainty means that the assessors and policy-makers must begin to consider how to interact with the public. This has been facilitated through data inventories and publication requirements from polluters covered under various environmental legislation and is referred to as risk communication (Santos 2007). Risk communication ensures that risk policies and messages are understood by the public, and through this understanding, induce behavioral change and enables more effective dispute resolution (Renn 1992; Santos 2007). Covello and Sandman (2001) describe the evolution of risk communication over the last 30 years. They identify risk as the combination of hazard and outrage to reflect the importance of both objective science and personal, contextual knowledge is shaping risk. Factors such as lack of control over decisions, distrust of organizations, and personal stake in risky activities can all change the perception of risk for people. In thinking about risk communication for this assessment we hope to avoid the one-way communication and isolation of affected populations typical of early risk assessment and communication.
In order to avoid adding to the perceived risk among members of this Appalachian community steps will be taken to include their perceptions in our risk characterization. The in-depth interviews used as part of the exposure assessment are intended to serve as a qualitative examination of how the community views risk. This may help to illuminate how the perception of risks in the community differs from a risk characterization informed by dose-response models and exposure assessments. This is an important first step to including some of the more subjective factors that determine risks for individuals. Knowing how community members define risk will allow us to speak to related factors in our risk characterization and may improve our relationship with the community. This can also help us to interpret the results of our risk assessment and provide useful recommendations to the community. The findings of our risk assessment will be presented to the community in stages in order to maintain a relationship with the community through repeat interactions.
A second approach in the follow-up of the original risk assessment will seek to put community members at the table with the facility operators. A trained mediator will moderate these meetings. This strategy is intended to facilitate more communication of risk between the two involved parties. It is hoped that this interaction will improve the community’s perceived and real influence over the situation, as well as reduce some of the sources for outrage that contribute to perceived risk (Covello & Sandman, 2001). Additionally information exchange between the facility and the community can help facility managers to understand the risks faced by the community. This can result in reductions in the health impacts of the risks, benefits from the risks the community does face, or effective prevention in increasing future risks (Fischhoff et al. 1993).
3
3) Air Quality and the Built Environment
a) Discuss the ways that a given built environment may serve as a modifier of individual exposure to both ambient- and indoor-generated air pollution.
Urban built environments are huge drivers of the impacts we have on ecosystems and the environment (Grimm et al. 2008). Air pollution in cities in a complex mixture of pollutants emitted from a multitude of sources as well as formed in the atmosphere. They are mobile, and varied by microenvironment (Mayer, 1999). Urban environments impact air pollution by concentrating sources, facilitating their formation though heat island effects (Stone, 2008) and influencing their distribution by creating turbulence and affecting regional weather patterns (Bornstein & Lin, 2000; Oke, 1987 p. 273). An important consideration for environmental health in cities relates to residents’ exposure to urban air quality conditions. Below I use the example of the characteristic sprawling city (think Atlanta) to illustrate some of the ways planning of the built environment can modify exposure to outdoor and indoor air pollutants.
Sprawl, Traffic, and Air Quality
A sprawling built environment, as discussed above (1b), influences ambient pollution in a number of ways. The impact of the built environment on air quality, in this respect, follows a path from land use and infrastructure, to travel behavior, to emissions, and then to ambient air quality (Frumkin et al. 2004). On a regional scale built environment patterns that eliminate the necessity of the automobile and make possible other less-polluting alternatives are important strategies for improving ambient air quality. On a smaller scale planning and the built environment can have significant influence over the exposures of populations to traffic-related pollution.
Reliance on the motor vehicle is crucial to connecting the today’s built environment to air quality (Frumkin et al. 2004 Ch. 4). Because the vehicle is such an important driver of ambient air pollution in cities today, the location and volume of cars in time and space is important for determining exposures. Several studies have focused on the spatial and temporal variability of pollution related to traffic and have shown that proximity to major roadways contributes to increased exposures (Brauer et al, 2003; Jerrett et al. 2005; Zhu et al. 2002).
Land Use Planning
Similar to the earliest zoning regulations that sought to remove noxious industries from the proximity of city dwellers, planning processes that regulate and design the built environment around major roadways have important influences on determining exposures. Planning new roadways can be expected to induce additional traffic and may increase local pollutant generation. This can potentially increase exposures for residents in close proximity. While new freeways are infrequently added to cities, widening of roadways are much more common and have induced demand effects on traffic. Communities near major roadway expansions may be disproportionately affected by such planning decisions. Planning can also influence exposures to traffic-related pollution by influencing the zoning around major roadways. Construction of buildings (home or work) in close proximity to major roadways can subject inhabitants to high ambient concentrations, which for PM2.5 can be translated into high indoor concentrations depending on ventilation factors, including whether windows are open (Sarnat et al. 2001; Sarnat et al. 2006). Because significant portions of an individual’s day are likely to be spent in these indoor environments, such zoning decisions have sizable effects on personal exposure. Several studies have examined the demographics around major roadways and found disproportionate siting of low-income populations. Thus, actions that lead to such patterns or that fail to resolve such problems may be considered environmentally unjust (Lee, 2005; O’Neill, et al. 2003).
Land use decisions also affect the locations of places we choose to exercise and take part in recreation. Proximity of parks and other open spaces to major roadways should also be considered for their potential impacts on exposure to air pollution. Exposures in parks represent especially important exposures since individuals who are exercising have elevated inhalation rates and may introduce particles deeper into the lungs (Bell & Samet, 2005). Additionally, parks are places where children often gather to play. Along these same lines, school siting decisions are a land use decision with important air pollution exposure consequences.
Land use not only affects those who live, work, and play near major roadways, but also the amount of time that everyone spends on roadways. Sprawling patterns of development increase trip length and the number of trips made by car and thus the amount of time we spend in cars. Concentration profiles show that commuting times represent daily peaks in ambient PM concentrations. More importantly exposures to PM while commuting mirror these peaks and suggest that nearly half of the total PM exposures were experienced while commuting (Kryzanowski et al. 2005 p. 87).
Sprawl and Time Spent Indoors
The automobile example above is a great case of a microenvironmental exposure that is influenced by the built environment. However the majority of our time is not spent in cars. We eat, sleep, work, socialize, and often exercise indoors. For many people it is conceivable that the only time they spend outside is to go between their car and different indoor environments. More time spent indoors results in greater exposures to indoor air pollution. This includes ambient pollution, which penetrates the building envelope but also involves many indoor sources. In recent times, the number of sources for indoor air pollution has also increased. They include off-gassing carpets, particle-producing printers and copiers, and volatile organic compounds from coatings and cleaners (Hodgson, 2005).
Sprawling built environment can also influence our exposures to indoor air pollution, again by directing behavior patterns. One way this has occurred is by privatizing public spaces. Detached single-family homes often come with yards and consequently new subdivision developments may not make provisions for public space within the development. This character of sprawl has combined with other social impacts that have reduced neighborhood social capital (Putnam, 2001). Social capital manifests itself as interaction among neighbors, participation in groups and clubs, and civic engagement. The decline of social capital has coincided with the ubiquity and multitude of in-home entertainment options. There is little reason to leave the house after arriving home from work. Sprawling patterns also lack connectivity, which necessitates the automobile even for short trips. Thus even trips to nearby public open space, are difficult to make without returning the to car microenvironment where, it is likely, you just spent the last half hour or more commuting home.
Sprawl and Stress
The stress caused by commuting is another way that the built environment and associated behaviors can influence the impact of exposures to air pollution. Stress can have effects on physiology and thus can interact with exposure to pollutants by affecting internal dose and the internally effective dose (Gee & Payne-Sturges, 2004). Commuting is one example of built environment-influenced stress; others are related to perceptions of the built environment, in particular safety. Proximity to loud or all-night businesses and industries can also increase stress.
Summary
The example of traffic in the city is illustrative of the importance of the built environment in and its effect on both air pollution sources and personal exposures to air pollution. As a driver of transportation related pollution planning decisions are important for reducing ambient concentrations. However, it is also related to exposures; as a determining factor for where people can live and work, but also as it influences the way we spend our time. Particularly when environment and behavior patterns result in the temporal and spatial coincidence of large numbers of people with high pollution concentrations. Moreover, the built environment has influences on the way we spend free time, and our access to outdoor environments. Finally, navigating and functioning within the built environment puts stress on us daily. The built environment’s role as both a driver of pollution and a determinant of exposure demands thoughtful consideration and coordination of plans to ensure that efforts to improve health by mitigating one aspect do not result in negative effects on the other (Frank & Engelke, 2005).
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