Consensus Study Report

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This study was supported by a contract number 6973GH-25-T-00001 (NAS AWD-002572) between the National Academy of Sciences and Department of Transportation/Federal Aviation Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.

International Standard Book Number-13: 978-0-309-59996-2
Library of Congress Control Number: 2026945884
Digital Object Identifier: https://doi.org/10.17226/29261

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2026. Assessing Radiation Exposure, Health Outcomes, and Mitigation Strategies for Flight Crewmembers. Washington, DC: National Academies Press. https://doi.org/10.17226/29261.

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COMMITTEE ON ASSESSING RADIATION EXPOSURE, HEALTH OUTCOMES, AND MITIGATION STRATEGIES FOR FLIGHT CREWMEMBERS

JONATHAN M. SAMET (NAM) (Chair), Professor and Former Dean, Colorado School of Public Health, University of Colorado, Aurora

AMIR A. BAHADORI, Professor, Alan Levin Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, Kansas

THOMAS A. BURKE, Professor Emeritus and Director Emeritus, Johns Hopkins Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland

CASEY I. CANFIELD, Associate Professor, Missouri University of Science and Technology, Rolla, Missouri

SARAH S. COHEN, Director of Public Health Research, DLH, LLC, Durham, North Carolina

MARDI CRANE-GODREAU, Independent Research Scientist, Author, and Assistant Editor at Frontiers in Public Health, Arlington, Vermont

LINDSAY S. FENWICK, Consultant (retired), Incline Village, Nevada

HEIDI A. HANSON, Senior Scientist and Group Lead of Biostatistics and Biomedical Informatics, Oak Ridge National Laboratory, Oak Ridge, Tennessee, and Adjunct Assistant Professor at University of Utah, Salt Lake City, Utah

BENJAMIN W. MCGEE, Assistant Director of Radiation Safety, Department of Environmental Safety, Sustainability and Risk, University of Maryland, College Park

CHRISTOPHER J. MERTENS, Senior Research Physicist, Space Radiation Group, NASA Langley Research Center, Hampton, Virginia

CHRISTOPHER SCHEIBLER, Chief Flight Surgeon, United States Air Force; Assistant Professor, Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biostatistics, Bethesda, Maryland; Affiliated Research Scientist, Harvard School of Public Health, Department of Environmental Health, Cambridge, Massachusetts

Study Staff

DANIEL J. MULROW, Study Director

REBECCA A. ENGLISH, Senior Program Officer

NICHOLAS A. MURDOCK, Associate Program Officer (as of April 1, 2026)

MADELINE L. JENSEN, Research Associate (as of October 31, 2025)

LYDIA TEFERRA, Research Associate (until October 24, 2025)

DARLENE GROS, Senior Program Assistant

REBECCA MORGAN, Senior Research Librarian and Team Lead Research Services

LAURA D. LLANOS, Financial Business Partner

CLARE STROUD, Senior Program Director, Biomedical and Health Sciences Program Area

CHARLES D. FERGUSON, Senior Board Director, Nuclear and Radiation Studies Board and Board on Chemical Sciences and Technology (until December 31, 2025)

THOMAS MENZIES, Senior Board/Program Director, Consensus and Advisory Studies Division

Reviewers

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.

We thank the following individuals for their review of this report:

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by LINDA H. CLEVER (NAM), California Pacific Medical Center, and GAYLE WOLOSCHAK, Northwestern University Feinberg School of Medicine. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

Acknowledgments

This study would not have been possible without the cooperation of many individuals and organizations who assisted with the study’s task.

The committee wishes to acknowledge the U.S. Department of Transportation for sponsoring this study. The committee also wishes to acknowledge Federal Aviation Administration (FAA) staff and contractors who provided guidance, expertise, and support to the study: Anthony Tvaryanas, Aerospace Medical Research Division manager, Civil Aerospace Medical Institute (CAMI); Kyle Copeland, health physicist and team coordinator for the Medical Research Team, CAMI; Stacey Zinke-McKee, branch manager, Human Protection and Survival Research Laboratory, CAMI; Hammad Baig, section manager, Life Science Research, CAMI; and Amie A. Simmons, research project manager, Chickasaw Health Consulting, contractor to the FAA Aerospace Medical Research Division. The committee is grateful to the many experts who presented and provided materials during its information-gathering sessions. The committee wishes to acknowledge the following individuals (in order of presentation across sessions): Rondeau Flynn, Allied Pilots Association; Judith Anderson, Association of Flight Attendants-CWA; Lori Vitto Glattly and Hayley Brewer, Association of Professional Flight Attendants; Diego Garcia, Aerospace Medical Association; Zac Dohnal, Air Canada; Francis Heil, Airlines for America; Renaud Fenster, Transport Workers Union (TWU) Local 579; Michael Massoni, TWU Local 556; Marissa Mianzo, Southwest Airlines; Todd Moore, Air Line Pilots Association, International; Alex Schroeder, American Airlines; Brent Weisner, Southwest Airlines Pilots Association; Michael McCall, PCAire; W. Kent Tobiska, Space Environment Technologies; Eric Benton, Oklahoma State University; Les Braby, Texas A&M University; Katherine Monson and Scott McIntosh, Hale SWx; and David A. Savitz, Brown University School of Public Health.

The committee also wishes to acknowledge Francis Heil, Airlines for America, for recommending speakers, providing additional contacts, and coordinating responses to a committee questionnaire to members of Airlines for America.

The committee wishes to acknowledge consultants Meghan Buran and Kevin Naaman, for their support, particularly for the literature assessment and creation of the forest plots in this report, respectively, and Roberta Wedge for her technical support.

The committee also wishes to acknowledge the many individuals, too numerous to list, who assisted with responses to information requests, provided materials for consideration, and shared expertise that informed the committee’s information-gathering activities.

The committee is grateful to the staff of the National Academies of Sciences, Engineering, and Medicine (the National Academies) for organizing and facilitating this study. Daniel Mulrow, study director, oversaw the information-gathering process and guided the report through writing, review, and publication. Rebecca English, senior program officer, provided oversight and support throughout the study. Madeline Jensen, research associate, assisted with information and data collection and figure preparation. Lydia Teferra, research associate, assisted with initial background research. Nicholas Murdock, associate program officer, for fact checking of the final report. Darlene Gros, senior program assistant, provided administrative support, including meeting coordination and assistance with report production. The committee also wishes to acknowledge Rebecca Morgan, National Academies Research Center, for performing the literature search and for developing methods and protocols for the literature review.

Contents

SYNOPSIS

SUMMARY

1 INTRODUCTION

Study Origin and Scope

Context and Background

Statement of Task

Aspects Beyond the Bounds of the Statement of Task

Committee’s Approach

Report Organization

References

2 EVIDENCE BASE AND INFORMATION GATHERING

Regulatory Landscape

Stakeholder Engagement

Implications for Policy and Practice

References

3 ASSESSMENT OF EPIDEMIOLOGIC LITERATURE

Literature Assessment

Evidence Synthesis: Cancer Outcomes

Evidence Synthesis: Reproductive Outcomes

Commonalities and Limitations

References

4 EVALUATION OF COMPUTATIONAL MODELS

Overview of Important Parameters for Radiation Exposure Assessment of Flight Crew and Current Validation of Models

Comparison of Codes to Estimate Radiation Dose

Cumulative Radiation Exposure Assessments

Framework for Occupational Profile

Using Codes to Evaluate Occupational Dose

References

5 EPIDEMIOLOGIC APPROACHES TO UNDERSTAND HEALTH RISKS

Epidemiologic Research Is Needed

Epidemiologic Research Considerations

Translating Exposures into Lifetime Risks

Feasibility and Design Considerations for Epidemiologic Studies

Approaches for Epidemiologic Research

Summary: Understanding Radiation Exposure and Health Outcomes Through Epidemiology

References

6 MANAGING AND COMMUNICATING RADIATION RISK FOR FLIGHT CREW

Justification for Action

Elements of a Radiation Safety Program

Mitigation Options in U.S. Aviation

Challenges and Opportunities in Communicating Radiation Risk to Flight Crew

Synthesis and Path Forward

References

7 THE WAY FORWARD

Moving Toward a Radiation Safety Program

Taking Action

References

Appendix A Biographical Sketches of the Committee and Project Staff

Appendix B Public Meeting Agendas

Appendix C Summary of Presentations

Appendix D Written Requests to Stakeholders

Appendix E Literature Review: Methods, Approach, and Results

Appendix F Information and Methodologies for Computational Models

Appendix G Information and Methodologies for Cancer Risk Calculations

Boxes, Figures, and Tables

BOXES

1-1 Statement of Task

1-2 Additional Contractual Tasks

4-1 Solar Weather Patterns and Contemporary Examples

6-1 Practical Limitations in the Use of the CARI Model for Flight Crew

6-2 Lay Perceptions of Radiation Risk

E-1 Key Terms for Types of Estimates Used in Forest Plots

FIGURES

1-1 Committee-calculated average dose rates (µSv/hr) at various altitudes averaged across the continental United States

4-1 Important parameters for radiation exposure: (A) the inverse relationship between the solar cycle and GCR, (B) atmospheric shielding, and (C) variances in geomagnetic shielding across the globe with respect to latitude

4-2 Solar storms: (A) Solar flares and (B) Coronal Mass Ejections

4-3 Effective dose calculated for individual flight paths for each code in (a) Solar Cycle 24 under solar maximum condition and (b) Solar Cycle 24 under solar minimum condition

4-4 Effective dose calculated for individual flight paths for each code during the 2003 Halloween SEP event at two different time points: (a) when the storm exhibited strong SEP flux and moderate geomagnetic storming, and (b) when the storm exhibited moderate SEP flux and strong geomagnetic storming

4-5 Effective dose calculated for individual flight paths for each code during the January 2005 event that exhibited a short-lived but intense SEP flux

4-6 Model-, trajectory-, and solar-condition-averaged annual doses to aircraft occupants by occupational profile

4-7 Model-, trajectory-, and solar-condition-averaged career doses to aircraft occupants by occupational profile

4-8 Great circle trajectories and associated four-model-averaged flight crew doses for each of the four flight paths modeled under averaged solar radiation conditions

4-9 Comparison of modeled annual doses to aircraft occupants under trajectory- and SC24 solar-cycle-averaged conditions for each occupational profile

4-10 Comparison of modeled career doses to aircraft occupants under trajectory- and SC24 solar-cycle-averaged conditions

5-1 Framework for cancer risk assessment associated with radiation exposure of flight crew

5-2 Lexis diagram showing the longitudinal follow-up of different cohort types and the motivation for a multi-cohort design

6-1 Example of an icon array to communicate population-level radiation exposure and cancer risk

E-1 Cancer outcomes PRISMA diagram

E-2 Reproductive outcomes PRISMA diagram

E-3 Forest plot showing the summarized results between flight crew radiation exposure and malignant melanoma

E-4 Forest plot showing the summarized results between flight crew radiation exposure and nonmalignant melanoma

E-5 Forest plot showing the summarized results between flight crew radiation exposure and breast cancer

E-6 Forest plot showing the summarized results between flight crew radiation exposure and prostate cancer

E-7 Forest plot showing the summarized results between flight crew radiation exposure and brain/central nervous system cancer

E-8 Forest plot showing the summarized results between flight crew radiation exposure and thyroid cancer

E-9 Forest plot showing the summarized results between flight crew radiation exposure and lymphoma

E-10 Forest plot showing the summarized results between flight crew radiation exposure and leukemia

G-1 Total number of recorded departures by year and haul class

G-2 Total number of pilots and copilots by airline and year for single-year snapshots at 5-year intervals between 1990 and 2020

G-3 Distribution of air time by haul class

G-4 Distribution of exposure estimate by haul class

TABLES

1-1 Broad Categories of Radiation Types in the Aviation Environment

1-2 Flight Crew Demographics from 2023

1-3 Summary of the Committee’s Information-Gathering Activities

2-1 Comparison of FAA and OSHA Authorities Concerning Occupational Exposure to Radiation

2-2 Comparison of U.S. Regulatory Agencies and Approach to Occupational Radiation–Exposed Workers

2-3 Summary of Specifications for Commercially Available Dosimeters Used in Aviation Environments

4-1 Considerations for Selection of Computational Models

4-2 Summary of Selected Codes and Comparison of Key Features

4-3 Route Selection and Committee Rationale for Inclusion in Analysis

4-4 Solar Weather Conditions and Committee Rationale for Inclusion in Analysis

4-5 Summary of AVIDOS Results (μSv)

4-6 Summary of CARI-7A Results (μSv)

4-7 Summary of NAIRAS Results (μSv)

4-8 Summary of SIEVERT Results (μSv)

4-9 Model-Averaged and Solar-Condition-Averaged Single-Flight Hourly and Total-Flight Whole-Body Effective Dose Received by Occupants for All Flight Trajectories Considered (mSv)

4-10 Model-Averaged and Solar-Condition-Averaged Cumulative Annual Occupational Flight Profile Doses for All Flight Trajectories (mSv)

4-11 Model-Averaged and Solar-Condition-Averaged Cumulative 47-Year Career Occupational Flight Profile Doses for All Flight Trajectories Considered (mSv)

4-12 Annual Occupational Flight Profile Exposures for Time-, Trajectory-, and SC24 Solar-Cycle-Averaged Conditions (mSv)

4-13 47-Year Career Occupational Flight Profile Exposures for Time-, Trajectory-, and Solar-Cycle-Averaged Conditions (mSv)

5-1 Challenges in Occupational Epidemiology Studies

5-2 Key Elements to Assess Radiation Risks to Flight Crew

5-3 Estimated Cumulative Number of Flight Crew Potentially Available for Epidemiologic Research, United States, 1999–2023

5-4 Potential Confounding and Modifying Factors in Flight Crew Studies

5-5 Key Assumptions Used in Simulation Modeling

5-6 Results of Power Calculations

6-1 Elements of a Radiation Safety Program and Application to Commercial Aviation

E-1 Studies Identified Reporting on Malignant Melanoma Among Flight Crew

E-2 Studies Identified Reporting on Nonmelanoma Skin Cancer Among Flight Crew

E-3 Studies Identified Reporting on Prostate Cancer Among Flight Crew

E-4 Studies Identified Reporting on Brain/Central Nervous System Cancer Among Flight Crew

E-5 Studies Identified Reporting on Thyroid Cancer Among Flight Crew

E-6 Studies Identified Reporting on Lymphomas Among Flight Crew

E-7 Studies Identified Reporting on Leukemias and Lymphomas Among Flight Crew

E-8 Studies Identified Reporting on Genital Cancer Among Flight Crew

E-9 Studies Identified Reporting on Spontaneous Abortion (SA) Among Flight Crew

E-10 Studies Identified Reporting on Birth Outcomes Among Flight Crew

E-11 Studies Identified Reporting on Birth Defects Among Flight Crew

E-12 Studies Identified Reporting on Sex Ratio Among Flight Crew

E-13 Studies Identified Reporting on Infertility Among Flight Crew

F-1 Commercial Flight Paths and Space Weather Conditions for Cosmic Radiation Exposure Model Evaluation

F-2 Ascent time from ground to cruise flight level and decent from cruise altitude to ground

F-3 Geographic latitudes and longitudes of airport city-pairs

G-1 Examples of Established Surveillance Programs in the United States

G-2 Flight Route Category

G-3 ERR per Gray by Cancer Site and Sex

G-4 Values Used in Simulations for Per-year Exposure Distributions

Preface

This report addresses the ubiquitous and unavoidable exposure of aircraft flight crew—those in the cockpit and those in the cabin—to naturally occurring galactic cosmic radiation and solar energetic particles. Ionizing radiation is a known cause of cancer and other adverse health outcomes, but the risks of the types of radiation received in-flight are not well characterized. The aggregate doses received during the hundreds to thousands of hours in-flight accumulate over a career may raise concern about increased risk for cancer and other adverse consequences for the health of flight crew. The Federal Aviation Administration (FAA), which has jurisdiction over the health and safety of cockpit crew and flight attendants, has acknowledged that radiation exposure occurs and in response has provided recommendations but no requirements regarding their exposure. This report responds to the need to address radiation safety for flight crew.

This report from the National Academies of Sciences, Engineering, and Medicine, called for in the FAA Reauthorization Act of 2024, provides a description of the radiation received by flight crew, what is known about its consequences, and an approach for moving forward in investigating and mitigating risks. The committee brought together experts spanning airline operations, computational modeling, cancer epidemiology, health physics, occupational health and safety, risk communication, risk assessment, radiation epidemiology, and radiation risk mitigation.

In completing its work, the committee conducted a review of the epidemiologic literature on cancer and reproductive outcomes among pilots and flight attendants, evaluated publicly available computational models used to estimate radiation dose in flight environments, and considered representative flight routes to estimate cumulative occupational exposures over a career. The committee also examined approaches to monitoring and mitigating radiation exposure in aviation settings. Its deliberations were informed by engagement with academic researchers, aircraft manufacturers, federal agencies, instrument developers, labor organizations, and U.S. commercial airlines,

which provided important technical and operational context for interpreting the available evidence.

The committee benefited from the insights and experiences shared by numerous representatives of flight crew organizations, who provided valuable perspectives on occupational conditions and concerns. Pilots and flight attendants are concerned about this exposure. The committee also acknowledges the contributions of Airlines for America, the trade association representing major North American airlines, in supporting information gathering for this study. In addition, the committee recognizes the sustained efforts of researchers working to characterize the radiation environment at aviation altitudes, to develop and refine computational models for estimating radiation exposure, and to better understand the potential associations between radiation exposure and adverse health outcomes. These contributions have been essential to advancing knowledge in this field.

The committee recognizes the complexity of this topic and the importance of continued research on coordination about, and attention to occupational radiation exposure in aviation. It urges coordinated action led by the FAA and involving other relevant organizations.

Jonathan M. Samet, Chair
Committee on Assessing Radiation Exposure, Health Outcomes, and Mitigation Strategies for Flight Crewmembers
March 2026

Acronyms and Abbreviations