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3 The communities surrounding airports have become increasingly aware of airport emis- sions and how they contribute to local air quality that may affect public health. The growth in airport operations as well as increased public awareness of health impacts, has spurred the need for airport operators to more fully understand the potential for health impacts and to develop better information and methods to share with the public. Understanding airport contributions to air quality is challenging because it involves many factors including, but not limited to, the following: â¢ Airport source characteristics (including pollutant emission rates), â¢ Type of pollutants, â¢ Location of sources and population, â¢ Meteorology, â¢ Seasonality, and â¢ Geography. Understanding airport contributions to local air quality can be complex because any of these factors can significantly impact airport contributions. They also can contribute in different ways and interfere dramatically with each other (i.e., one factor can interfere with the efficacy of another). For example, one airport may generate lower emissions of certain pollutants, such as nitrogen oxides (NOx), but because the surrounding region experiences weather conditions and a geography that is more conducive to the formation of ozone (O3), the airport may be seen as contributing more to the detriment of local air quality than another airport that may produce higher emissions of NOx. The story becomes more complicated when health effects are being considered, as this depends on the location of the population as well as their vulnerability characteristics. Two different airports may have similar sources (e.g., similar aircraft fleet mixes) resulting in similar concentrations for each pollutant, but if the population surrounding one of the airports is directly downwind of the airport while the population for the other airport is predominantly upwind, the former airport may be seen as contributing more to public health impacts than the latter airport. These examples illustrate the interactive nature of various factors but they also show that airports can vary significantly for each factor. As such, definitive generalizations cannot be made when considering the air quality and corresponding health impacts from airports. Each airport needs to be considered separately when assessing specific air quality contributions and potential public health impacts. With these qualifiers in mind, some conclusions can be drawn from the existing literature of airport studies to help better understand the state of research and its findings. C H A P T E R 1 Introduction
4 Understanding Airport Air Quality and Public Health Studies Related to Airports 1.1 Goal and Scope Many studies have used different methods and data to characterize airport contributions to local air quality and potential health impacts. As such, the scope and approaches utilized in airport-related air quality and public health studies vary widely, resulting in conclusions that can vary widely as well. This variability and insufficient information can make it difficult for airports to properly respond to proximate communities that are concerned about health impacts and look to the airports for answers. Because of the lack of specific guidance regarding the understanding of airport impacts on public health, the Transportation Research Board (TRB) funded this project under the Airport Cooperative Research Program (ACRP). The goal of the project was to develop a guidebook to help inform airport operators and allow them to better respond to public concerns over air quality and health impacts in the vicinity of airports. Overall, the project involved a formal literature review and a critical synthesis of the existing knowledge base. This included reviews of each of the aforementioned factors affecting airport contributions to local air quality and of health impact assessments involving risk estimations to provide an understanding of the current state of knowledge of airport contributions to air qual- ity and health impacts. It should be noted that while pertinent (airport-centric) health-related studies were reviewed in the development of this report, it is not an exhaustive summary, as there are thousands of health studies that address pollutants related to airport emissions but are not specific to airport settings. The composition of the literature materials reviewed for this section includes reports, documents, and articles from various sources including universities, state air agencies, FAA, airport monitoring studies, etc. Most of the reviewed literature is focused on the United States, Common Terms EmissionâThe release of a pollutant from a source (e.g., aircraft engine) and quantified in mass units such as kilograms and pounds. Emission FactorâThe rate of release of a pollutant from a source, typically quantified as mass per activity (e.g., grams/hour). ConcentrationâThe amount (mass) of pollutant(s) within a volume of air with units such as parts per million (ppm) and micrograms per cubic meter (Âµg/m3). A concentration value represents the quality of the air to which human beings can potentially be exposed. ReceptorâA location of interest where an air quality concentration is experienced (e.g., a location representing public exposure). DispersionâThe scattering or diffusion of a pollutant in the air after release from a source. Health RiskâThe chance of harm due to exposure to a pollutant. ToxicityâThe degree to which a pollutant can harm a human being. ExposureâRefers to the âcontactâ a human being may experience with a pollutant (i.e., breathing in a pollutant).
Introduction 5 but some non-U.S. studies also were included. Since there were many potential studies to review, the focus was first placed on those that directly covered airport air quality contributions and health impacts. After this, the reviews were expanded to include documents related to airport ambient measurements and airport air quality modeling. Then more general health impact documents were included. Appendix A provides a list of the documents reviewed under this project in the form of a matrix, look-up table where each document has been assigned categorization factors for easier grouping and identification. The overall scope of this project involved answering key questions related to airport health impacts. As such, it included the development of concise summaries of findings from the litera- ture and appropriately interpreting and critiquing the materials. Although not all of the literature materials listed in Appendix A were cited, they were all reviewed for this project. 1.2 Organization Chapters 2 through 4 present concise background materials to help better understand airport air quality issues and concepts. Chapter 2 provides a review of air quality regulations. Chapter 3 provides descriptions of airport sources and factors affecting airport air quality. Chapter 4 provides a concise primer on pollutant health effects and risk assessments. Pollutants of Interest at Airports Criteria Pollutants â¢ Carbon monoxide (CO) â¢ Lead (Pb) â¢ Nitrogen dioxide (NO2) â¢ Particulate matter with an aerodynamic diameter 10 Âµm (PM10) or lessâcoarse particles â¢ Particulate matter with an aerodynamic diameter 2.5 Âµm (PM2.5) or lessâfine particles â¢ Ozone (O3) â¢ Sulfur dioxide (SO2) Hydrocarbons (HCs) Volatile Organic Compounds (VOCs) Hazardous Air Pollutants (HAPs) â¢ Volatile organic compounds â¢ Aldehydes and ketones â¢ Dioxins and furans â¢ Polycyclic aromatic hydrocarbons (PAHs) â¢ Metal compounds Ultrafine PM â¢ Particulate matter with an aerodynamic diameter less than 0.1 Âµm Other PM Types and Components â¢ Black carbon (BC or elemental carbon) â¢ Nitrates â¢ Sulfates
6 Understanding Airport Air Quality and Public Health Studies Related to Airports Chapter 5 presents the findings of the researchersâ critical reviews. This chapter is com- prised of two sections dealing with pollutant prioritizations and quantifying the contribution of airports to local air quality and health impacts. Chapters 6 and 7 provide the conclusions and recommendations for future research. The recommendations also serve to point out any knowledge gaps. The last three sections provide a list of acronyms; Appendix A, the matrix of references; and Appendix B, Frequently Asked Questions (FAQs). The FAQs section was added to help readers obtain quick answers to commonly asked questions.