Effective Methods for Environmental Justice Assessment (2004) / Chapter Skim
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Pages 58-92
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From page 58... ...
In cases where protected populations are very concerned about air quality, it may not be enough to assess the impact from transportation system changes. Because it is the cumulative exposure to all air pollutants that affect human health and quality of life, many environmental justice proponents have recommended evaluating the distribution of pollutants from all sources.
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From page 59... ...
The basic assumption is that, unless the standards are violated, there is no adverse effect to be evaluated for distributive effects to protected populations. Given this assumption, some argue that transportation air quality is not an important environmental justice issue because policies, projects, and programs cannot be implemented if they violate the standards.
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From page 60... ...
61 Table 3-1. Effects of criteria pollutants Pollutant Description Ozone (O3)
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From page 61... ...
This evaluation assesses the regional impacts that transportation investments will have on emissions in nonattainment or maintenance areas. Information required to perform a regional air quality assessment includes the following: • Estimates of current and future population and employment; • Estimates of current and future travel and congestion; • Assumptions about current and future background pollutant concentrations;
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From page 62... ...
. Base Year Future Year Regional travel demand model Modeled VMT by roadway class Congested speeds by roadway class HPMS-adjusted VMT by roadway class Emissions factors by roadway class MOBILE Regional travel demand model Future year modeled VMT by roadway class Base year modeled VMT by roadway class Base year HPMS-adjusted VMT by roadway class O ff -m o d e l p o s t p ro c e s s in g Regional emissions HPMS VMT by roadway class Base year HPMS to model adjustment factors by roadway class HPMS-to-model VMT adjustment Modeled VMT growth rate by roadway class Emissions computations Travel computations Highway performance monitoring system (HPMS)
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From page 63... ...
Although the results of these analyses generally are considered to be reasonably accurate, the highly localized nature of the assessment makes it difficult to directly relate any violation to disparate effects on protected populations. If an air quality impact were
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From page 64... ...
Mitigation measures Local air quality mitigation measures. If violations of local standards or the NAAQS are predicted to result from a proposed transportation project, mitigation measures would be required.
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From page 65... ...
Method 1. General air quality review When projects do not warrant an air quality analysis, the assessment may extend only to a general discussion about air quality rules and the existing air quality environment.
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From page 66... ...
Information gathered for this assessment can be used to perform detailed microscale analysis and detailed regional air quality analysis if findings indicate the potential for adverse effects to protected populations. Detailed microscale or regional air quality analyses may not be necessary if the project does not trigger the requirements for a conformity determination or if the project is within an attainment area or a maintenance area with specific guidance that does not require a detailed microscale analysis.
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From page 67... ...
This analysis is a process of documenting regional and local air quality issues, and then documenting the presence of protected populations in the study area to determine (on a qualitative basis) whether the proposed transportation system change could potentially cause distributive effects.
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From page 68... ...
For projects with smaller study areas, it is more appropriate to use data gathering techniques to characterize protected populations. Suggested techniques include local knowledge, field surveys, and public participation-based techniques such as focus groups.
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From page 69... ...
A general air quality review is intended to disclose local and regional air quality concerns and regulations. For environmental justice assessment, comparison of mobile and stationary air quality sources and their proximity to protected populations is included.
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From page 70... ...
For general NAAQS conformance with an environmental justice component, the objective could be stated as "document NAAQS compliance ensuring that the proposed projects cause no violations at worst case intersections and in areas where there is possible environmental justice concern." In situations where air quality is highly controversial and there is a history of concern over impacts to protected populations, the objective could be to obtain emissions reductions. In this case, the goal would be to "evaluate project performance and ensure that the transportation facility yields a net emissions reductions once it is fully implemented." Once the transportation system change and objectives are described, you must assemble all the data necessary to describe intersection-related traffic conditions and demographic characteristics of the intersections.
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From page 71... ...
Example of a microscale environmental justice assessment process Source: FHWA 2001. The results of this step would lead to a finding of distributive effects to protected populations in two cases:
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From page 72... ...
Initial findings, however, can be made simply by identifying where the "high-EJ concern" intersections fall in relation to the worst case intersections. In general, a finding of adverse distributive effects to protected populations would be warranted based on the following results: • Fifty percent or more of the worst case intersections are in areas of high environmental justice concern.
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From page 73... ...
However, due to the localized nature of effects being addressed by the microscale analysis, it is more appropriate to use demographic data collected for specific receptors using field survey, local knowledge, public input, and other detailed data-gathering techniques. A microscale intersection analysis is limited by the fact that only discrete receptors are analyzed.
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From page 74... ...
Because this technique provides only regional estimates and does not provide geographic distinction below the regional level, environmental justice assessment of regional air quality merely involves documenting the protected populations in the region and the air quality concerns that have been raised by those populations. Many of the analysis steps and issues discussed as part of the general air quality review (Method 1)
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From page 75... ...
Step 2 – Document air quality concerns of protected populations. Once the regional air quality analysis is completed, present the findings to protected population groups and address any questions or concerns.
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From page 76... ...
The general air quality review is suitable as a screening technique, but it only provides information as to whether a transportation policy, program, or project may have effects to protected populations, in which case a more detailed assessment technique must be used to characterize the effects. The detailed microscale analysis provides an indication as to how protected populations would be affected at worst case sites, commonly intersections, within a study area.
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From page 77... ...
Statistical methods are techniques that use a combination of regression analysis and known concentrations from monitoring sites to predict pollutant concentrations across the entire study area. Recent examples of model-based research and statistical method research are described below.
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From page 78... ...
This is because monitoring networks generally are sparse and thus do not accurately depict pollutant distributions that are affected by complex topography, complex meteorology, and rapid distance decay functions. Many approaches are used to develop regression models for estimating pollution surfaces.
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From page 79... ...
Land cover High density residential Measured pollutant concentrations Monitoring site adjusted mean concentration Weighted built land factor Weighted traffic factor Altitude Regression model Grid Pollution surface Sampler height Industrial Traffic flows Road network Traffic volume Figure 3-5. The SAVIAH statistical pollution surface development process Source: Briggs, et al.
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From page 80... ...
The groundlevel pollutant concentrations are based on meteorological conditions and the emissions estimates obtained for each grid cell. The physical properties of the pollutant and distance decay functions are also accounted for in the model.
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From page 81... ...
Based on computed predictor variable values for each grid cell, use the selected regression equation to compute predicted pollutant concentrations. This yields a pollution surface for the entire study area.
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From page 82... ...
By using the same set of grid cells to produce pollution surfaces and population surfaces, you create an information-rich dataset that can be evaluated to assess unequal distributive effects to protected populations. More detail on the process for developing population surfaces is provided in Chapter 2.
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From page 83... ...
Tabulated population characteristics and concentrations for each grid cell Determine distributive effects and evaluate significance Average emissions burden for PP, NPP, and TP Map PP and pollutant concentration Comparison charts Figure 3-6. GIS process for combining pollution surfaces and population surfaces The EPA approach based estimates of emissions burden on proximity to pollution sources and on estimates of pollutant emissions in pounds.
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From page 84... ...
When evaluating the codistribution of air quality effects and protected populations, visualizing the information patterns in graphs and maps is often the most insightful form of analysis. To produce graphs, the pollution surface must be combined with a population surface, which yields an estimate of pollutant concentration and protected population characteristics for each grid cell.
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From page 85... ...
If you rely on just the graphs, however, it is easy enough to understand that a disproportionate pattern exists but impossible, without the map, to determine where the patterns are located. Regional analysis is thus a combination of determining relative emissions burden and visualizing any potential disparities using graphs and maps.
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From page 86... ...
Proportion of Specific Population Group 0 5 10 15 20 25 30 35 40 45 0-5 6-10 11-30 31-40 41-50 51-55 56-60 61-65 PM10 Concentration (micrograms/cubic meter) P er ce n t o f P o p u la ti o n Protected Population Other Population Threshold of Concern Above PM10 NAAQS Unequal exposure at levels between 31 & 60 micrograms/cubic meter Total Persons 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000 0-5 6-10 11-30 31-40 41-50 51-55 56-60 61-65 PM10 Concentration (micrograms/cubic meter)
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From page 87... ...
88 Percent of Total Population Number of Persons Figure 3-8. PM10 concentration and protected population patterns in a regional study area
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From page 88... ...
Unlike the micro-scale analysis and regional air quality assessment methods, this method has not yet been mandated, or even widely accepted, as part of the regulatory process. The assessment of relative emissions burden is not the same as determining if people in the study area are exposed or if the level of exposure varies by person.
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From page 89... ...
P o p u la ti o n C o u n t Protected Population Other Population Threshold of Concern Above PM10 NAAQS Unequal exposure at levels between 6 & 55 micrograms/cubic meter Figure 3-9. Comparison of alternative project alignments Data needs, assumptions, and limitations of population surfaces are discussed in Chapter 2.
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From page 90... ...
Analysis of local and regional air quality using pollution surfaces and population surfaces is a very useful technique for evaluating distributive air quality effects to protected populations. Pollution surfaces can be developed using models that extend commonly used regulatory models to account for geographic variability in pollutant concentrations.
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From page 91... ...
It includes information on NAAQS, approved models for evaluating transportation conformity, a discussion on how to perform a regional air quality analysis, and information on how to perform a microscale analysis.
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From page 92... ...
1999. "Environmental Justice and Statistical Summaries of Differences in Exposure Distributions." Journal of Exposure Analysis and Environmental Epidemiology.
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