CHAPTER 1: Introduction

The communities surrounding airports have become increasingly aware of airport emissions and potential impacts of those emissions on local air quality and public health. Those concerns along with growth in airport operations have spurred the need for airport operators to more fully understand the potential for health impacts related to airport operations and to develop better information and methods to share this information with the public. Understanding airport impacts on air quality is challenging because it is affected by many factors including, but not limited to, the following:

• Airport source characteristics (including pollutant emission rates),
• Type of pollutants,
• Location of sources and population,
• Meteorology,
• Seasonality, and
• Geography.

All of these factors can significantly impact airport contributions to local and regional air quality. In addition, the health impacts associated with airport emissions depend on the location of the population as well as their susceptibility and vulnerability characteristics. Aircraft tend to contribute more to pollutant concentrations and health impacts of communities that are located downwind of airports than to those located upwind. However, the distance between airport sources, particularly runways, and neighborhoods or other sensitive receptors, may be even more relevant in determining health impacts due to variations in wind direction. Emissions from airport ground vehicles and other combustion sources may also impact local communities, but those emissions may have different impacts depending on the location and composition of the emissions.

Airports are complex facilities, each with unique characteristics impacting air quality and public health. The factors listed above differ by airport, making it difficult to generalize the impacts of airports on air quality and public health. As such, each airport should be evaluated separately when attempting to quantify air quality contributions and public health impacts from an airport. Nonetheless, there are some conclusions that can be drawn from the existing body of literature related to airport studies to help better understand the state of research and its findings.

1.1 GOAL AND SCOPE

Variations in the scope and approaches utilized in airport-related air quality and public health studies affect the conclusions of those studies. This variability and insufficient information can make it difficult for airports to properly respond to proximate communities that are concerned about health impacts.

In 2015, the Transportation Research Board (TRB) funded ACRP Project 02-42 to provide operators with information on airport impacts on public health. That project developed ACRP Report 135 Understanding Airport Air Quality and Public Health Studies Related to Airports, which includes a guidebook to provide airport operators with information needed to better respond to public concerns over air quality and health impacts in the vicinity of airports. Since that report’s publication, regulations and guidance have been updated, the science has continued to advance, and new areas of interest and research are being explored (e.g., UFPs, EJ, and indoor air quality). As a result, ACRP funded project 02-95 to update Report 135 to include the latest information on the impact of airport operations (e.g., aircraft, ground service equipment, ground transportation, and stationary sources) on air quality and public health to aid airport operators in responding to concerns about air quality at airports and in their surrounding communities. This current report update builds upon Report 135, adding additional relevant information and revising or removing information that is no longer relevant or accurate.

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 quality and health impacts. It should be noted that while pertinent (airport-centric) health-related studies were reviewed in the development of this report, it does not include the thousands of health studies that assess pollutants that may be emitted through airport activities but are not specific to airport settings. Additional information related to the health effects of air pollutants can be found on EPA’s Integrated Science Assessments (ISAs) website (at www.epa.gov/isa). The ISA program intends to “accurately reflect the latest scientific knowledge useful in indicating the kind and extent

of identifiable effects on public health and welfare which may be expected from the presence of pollutant(s) in the ambient air.”

The updated literature review for ACRP 02-95 focused on identifying new information or information that had changed since the time of Report 135. As such, the literature review primarily focused on sources that were published in 2015 or later. Additionally, this literature review was also focused on identifying information and research related to three additional topics related to airport air quality impacts: UFPs, indoor air pollution, and EJ. The searches used various combinations of keywords related to the study topics, including “aviation emissions,” “indoor air quality,” “airport,” “public health,” “environmental justice,” and “air pollution” as well as specific pollutants such as ozone and UFPs.

Materials reviewed for this project include reports, documents, and articles from sources including universities, state air agencies, the Federal Aviation Administration (FAA), the EPA, airport monitoring studies, health organizations, and others. The initial focus of this literature review was on identifying studies that directly addressed airport air quality contributions and health impacts. Next, the search was expanded to include research related to airport ambient measurements and airport air quality modeling. These were supplemented with more general health impact studies, evaluating the toxicity of relevant pollutants. The collected papers and articles were reviewed and evaluated in detail for relevance, appropriateness, and applicability to this study, and summaries of the study purpose, methods, and results, along with other key information including emission sources, pollutants, and study topics, were recorded in a tracking spreadsheet. For the current literature review, Appendix A (a supplemental spreadsheet) provides a list of the documents reviewed under ACRP 02-95 in the form of a matrix, lookup spreadsheet table where each document has been assigned categorization factors for easier grouping and identification. To assist readers just looking for a specific reference, citations for the references from the spreadsheet Appendix A are listed in alphabetical order in the printed Appendix A. The supplemental spreadsheet should be used to identify studies covering a particular topic area or to see brief summaries of the information in each study. Appendix B lists the literature sources identified in the original Report 135, many of which are still cited in this current report.

The overall scope of this project involved answering key questions related to airport health impacts. As such, it included summarizing the findings from the reviewed literature and appropriately interpreting and critiquing the materials. Although not all of the literature materials listed in Appendix A and Appendix B are cited in this report, they were all reviewed in the development of either Report 135 or the current report.

1.2 ORGANIZATION

Chapters 2 through 4 present background information to help better understand airport air quality issues and concepts. Chapter 2 provides a review of air quality regulations relevant to airport emission sources. Chapter 3 provides descriptions of airport emission sources and factors affecting airport air quality. Chapter 4 provides a primer on pollutant health effects and risk assessments related to pollutants emitted by airport sources.

Chapter 5 presents the findings of the researchers’ critical reviews. Chapters 6 and 7 provide the conclusions and recommendations for future research. The recommendations also serve to point out any knowledge gaps.

The last four sections provide a list of acronyms; Appendix A, the matrix of references identified and reviewed during this report update; Appendix B, the references from Report 135; and Appendix C, Frequently Asked Questions (FAQs). The FAQs section was added to help readers obtain quick answers to commonly asked questions.