Report to the Administrator

on the National Research Council Report,

"The Airliner Cabin Environment and the

Health of Passengers and Crew"

February 6, 2002

####### 

![](media/image1.png){width="2.1131944444444444in"
height="2.082638888888889in"}

Prepared by

The Airliner Cabin Environment Report Response Team

(ACERRT)

#  {#section-1 .unnumbered}

Table of Contents

The Airliner Cabin Environment Report Response Team
[ii](#the-airliner-cabin-environment-report-response-team)

Executive Summary [iii](#executive-summary)

Preface [1](#preface)

NRC Recommendation 1 -- Air Quality Regulations
[3](#nrc-recommendation-1-air-quality-regulations)

NRC Recommendation 2 -- Regulations for Ozone
[13](#nrc-recommendation-2-regulations-for-ozone)

NRC Recommendation 3 -- Air Cleaning Equipment
[16](#nrc-recommendation-3-air-cleaning-equipment)

NRC Recommendation 4 -- Carbon Monoxide Monitoring
[18](#nrc-recommendation-4-carbon-monoxide-monitoring)

NRC Recommendation 5 -- Allergens [21](#nrc-recommendation-5-allergens)

NRC Recommendation 6 -- Health Information
[24](#nrc-recommendation-6-health-information)

NRC Recommendation 7 -- Ventilation Shutdown
[26](#nrc-recommendation-7-ventilation-shutdown)

NRC Recommendation 8 -- Surveillance Program
[28](#nrc-recommendation-8-surveillance-program)

NRC Recommendation 9 -- Research Program
[31](#nrc-recommendation-9-research-program)

NRC Recommendation 10 -- Research Program Lead Agency
[35](#nrc-recommendation-10-research-program-lead-agency)

Appendix 1 -- Regulations and Related Material Cited in the Report
[36](#appendix-1-regulations-and-related-material-cited-in-the-report)

14CFR Part 25, §25.831 - Ventilation
[36](#cfr-part-25-25.831---ventilation)

14CFR Part 25, §25.832 - Cabin Ozone Concentration
[37](#cfr-part-25-25.832---cabin-ozone-concentration)

14CFR Part 121, §121.578 - Cabin Ozone Concentration
[38](#cfr-part-121-121.578---cabin-ozone-concentration)

14CFR Part 25, §25.841 - Pressurized Cabins
[39](#cfr-part-25-25.841---pressurized-cabins)

14CFR Part 21, §121.805 - Crewmember Training for In-flight Medical
Events
[40](#cfr-part-21-121.805---crewmember-training-for-in-flight-medical-events)

The Air Carrier Access Act (ACAA) Rules
[40](#the-air-carrier-access-act-acaa-rules)

FAA Advisory Circular 120-44A [41](#faa-advisory-circular-120-44a)

Appendix 2 -- Abbreviations and Acronyms Used in the Report
[42](#appendix-2-abbreviations-and-acronyms-used-in-the-report)

#  

# 

# The Airliner Cabin Environment Report Response Team

**(ACERRT)**

#### Judi M. Citrenbaum

Program Analyst

Medical Specialties Division

Office of Aerospace Medicine

#### Nancy Lauck Claussen

Cabin Safety Inspector

Flight Standards Service

#### Stephen Happenny

Aerospace Engineer

Environmental Control System Specialist

Transport Airplane Directorate

Aircraft Certification Service

#### Gene Kirkendall

FAA/OSHA Aviation Safety

and Health Team Leader

Flight Standards Service

#### Arnold G. Konheim

Senior Policy Analyst

Office of the Secretary

U. S. Department of Transportation

#### Noal D. May, Ph.D.

Certified Industrial Hygienist

Occupational Health Division

Civil Aerospace Medical Institute

#### Garrison Rapmund, M.D.

Consultant to the Federal Air Surgeon

#### Charles Ruehle, M.D.

Manager, Certification Appeals Branch

Office of Aerospace Medicine

#### 

#### Robert M. Shaffstall

Manager, Protection and Survival Laboratory

Aeromedical Research Division

Civil Aerospace Medical Institute

#### Michael B. Smith

Technical Advisor to the Administrator

Office of the Administrator

#### Jean Watson 

Program Manager

Maintenance Technologies and Procedures

Aircraft Maintenance Division

Flight Standards Service

#### James E. Whinnery Ph.D., M.D.

Manager, Aeromedical Research Division

Civil Aerospace Medical Institute

#### Dee Wolf

Secretary

Office of Aerospace Medicine

#### Invited Participants:

#### 

#### Brenda Courtney

Manager, Aircraft & Airport Rules Division

Office of Rulemaking

#### 

#### Jeffry Goode

Economist

Office of Aviation Policy and Plans

#### Ida M. Klepper

Manager, Airmen & Airspace Rules Division

Office of Rulemaking

#### 

#### Lyle Malotky, Ph.D.

Chief Scientific & Technical Advisor

Civil Aviation Security

#### 

#### Tim Marker

Aerospace Engineer, Fire Safety

Office of Aviation Research

#### 

#### Thomas McCloy

Scientific & Technical Advisor, Human Factors

Office of Aviation Research

#### 

#### Louise Speital

Chemist

Office of Aviation Research

# Executive Summary

The National Research Council (NRC) conducted a study and issued a
report in December 2001 on *The Airliner Cabin Environment and the
Health of Passengers and Crew,* as called for in the Wendell H. Ford
Aviation Investment and Reform Act for the 21^st^ Century (PL106-181).
The report included ten recommendations regarding new regulations,
investigations, and initiatives in public information, surveillance, and
research. The report reiterated concerns raised in a similar 1986 report
and highlighted the need for better data to determine the relationship
between cabin air quality and health problems and complaints among
passengers and crewmembers.

The Federal Aviation Administration (FAA) generally concurs with the
intent of the recommendations and welcomes the report's emphasis on an
increased data collection and research capacity to investigate issues
related to a healthy cabin environment. FAA has begun the rulemaking
process to determine if new regulations are required. It also has taken
other steps short of rulemaking to address the recommendations.

Most important, FAA recognizes that technology advances in identifying
chemical and biological (C/B) terrorist threats have important
implications for cabin air quality. Deploying C/B sensor technology on
commercial aircraft opens the way for on-board sensors for air quality
markers and communicable diseases. The FAA response to NRC's
recommendations should be viewed as interim steps to a much broader
vision of a secure and healthy aviation system.

NRC's Recommendations 1-4 focused on specific aspects of air quality
issue and called for FAA to:

-   Use "quantitative evidence and rationales" to support its existing
    and proposed regulations related to air quality and change the
    ventilation standard

-   Mandate the use of ozone converters or prohibit flights above 25,000
    feet

-   Investigate the need for particulate filters and gaseous filtration
    systems on all aircraft

-   Require a CO (carbon monoxide) monitor in the air supply ducts to
    passenger cabins

FAA is tasking an Aviation Rulemaking Advisory Committee (ARAC) to
review existing standards and propose revisions or new standards.
However, it is not convinced of the need to monitor all of the air
quality characteristics noted by NRC for routine surveillance for
elevated CO concentrations. FAA prefers a system that will ensure that
the flight crew is aware of an "air contaminant" event and will identify
its source.

NRC's Recommendation 5 called for an investigation by FAA to determine
if, because of allergy concerns, small animals should be prohibited in
airplane cabins. It also recommended that cabin crews be trained to
recognize and respond to severe reactions to airborne allergens. FAA
recognizes that allergens in the airplane cabin are a potentially
life-threatening issue for a small segment of the airline passenger
population. It does not believe that prohibition of animals in the cabin
would be effective. However, it will issue an Advisory Circular that
incorporates the most effective industry practices regarding passenger
handling procedures for allergen-sensitive people seated close to
animals. The circular also will address the importance of crewmember
training in recognition and response to in-flight medical events that
result from allergen exposure. In addition, every effort will be made to
ensure that flight attendants and the aviation community in general have
the most up-to-date information for the treatment of allergen-related
medical events. Finally, information on airline policies for the
transportation of animals will be disseminated to the public.

NRC's Recommendation 6 called for increased efforts to provide
information on health issues related to air travel and especially on the
potential risks of flying. FAA concurs with the recommendation and will
continue to focus the attention of its Office of Aerospace Medicine on
health issues faced by passengers and crewmembers. It also will increase
the information and recommendations that are available on public web
sites.

NRC's Recommendation 7 repeated its 1986 call for a regulation to
require air carriers to remove all passengers from an aircraft within 30
minutes after a ventilation failure or shutdown on the ground. FAA
concurs with the objective of the recommendation and believes that it
can be achieved by issuing an Advisory Circular to air carriers on the
subject.

NRC's Recommendation 8, 9, and 10 called for:

-   An FAA surveillance program for air quality and health that would
    provide the data to analyze the relationship between cabin air
    quality and health effects or complaints

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-   A range of potential research efforts that would be defined, in
    part, by the data gathered through surveillance

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-   Congressional designation of a lead agency and funding for a
    research program with an independent advisory committee

FAA concurs with these three related recommendations and will propose
that Congress designate and fund FAA as the lead federal agency for the
air quality research program.

FAA also will recommend to the Secretary of Transportation that a
cooperative effort with the Transportation Security Administration (TSA)
be initiated to place sensor devices on U.S. air carrier aircraft. The
devices would monitor cabin air quality and detect biological and
chemical contamination of cabin air in a manner that warns the aircrew
and locates the source of contamination.

If accepted by the Secretary of Transportation, a research council
administered by both FAA and TSA would provide oversight for the
monitoring and research efforts. The Safety Subcommittee of FAA's
Research, Engineering and Development (RE and D) Advisory Committee
could provide technical oversight. The expanded nature of the response
will require additional resources beyond those necessary to meet the
basic NRC recommendations. The Administrator will request additional
funding from Congress to support the cabin air monitoring and data
collection as well as the research initiatives recommended by NRC.

# Preface

Section 725 of the Wendell H. Ford Aviation Investment and Reform Act
for the 21^st^ Century (PL106-181), enacted on April 5, 2000, directed
the FAA Administrator to

> ...provide necessary data to the National Academy of Sciences to
> conduct a 12-month, independent study of air quality in passenger
> cabins of aircraft used in air transportation and foreign air
> transportation, including the collection of new data, in coordination
> with the Federal Aviation Administration, to identify contaminants in
> the aircraft air and develop recommendations for means of reducing
> such contaminants.

The National Research Council (NRC), the principal operating agency of
the National Academy of Sciences (NAS) and the National Academy of
Engineering, conducted the study and issued its report, *The Airliner
Cabin Environment and the Health of Passengers and Crew*, in December
2001. The report included nine recommendations to FAA and one to
Congress that called for new regulations, further investigations in
specified areas of concern, and increased efforts in public information,
surveillance, and research.

The Federal Air Surgeon, Jon L. Jordan, M.D., took responsibility for
preparing a Report to the Administrator that would summarize NRC's
recommendations and present FAA's response to them. He created an
inter-disciplinary group, the Airliner Cabin Environment Report Response
Team (ACERRT), chaired by Charles Ruehle, M.D., Manager of the
Certification Appeals Branch, Office of Aerospace Medicine. The group
met weekly over a period of two months to study NRC's report, determine
what has been done and is being done to address the concerns raised in
the report, and develop an appropriate FAA response to NRC's
recommendations.

The Report to the Administrator quotes in full each of NRC's ten
recommendations, followed by the FAA response to the recommendation and
a discussion of the issues on which that response was based. FAA concurs
with the intent or objective of most of the recommendations, although
not always with the specific proposals for action. For many of the
recommendations, actions that address the underlying concerns have been
taken already or are in progress.

Viewed as a whole, NRC's report should be seen as evidence that
passengers and crewmembers on commercial aircraft have a continuing
concern about a variety of health and comfort problems that they ascribe
to poor air quality in airliner cabins. Such concerns are not a new
phenomenon. NRC conducted a similar study fifteen years ago and
presented similar findings and recommendations. Some actions were taken
as a result of the 1986 study, notably the ban on smoking on all U.S.
domestic flights. However, neither NRC nor FAA has sufficient data to
assess objectively passenger and crewmembers' complaints, design
effective interventions, or determine whether rulemaking or guidance
will be the most effective tactic for making changes.

To monitor cabin air quality and use the resulting data to establish or
rule out cause-and-effect relationships between air quality and
complaints of discomfort and health problems will be a costly
enterprise. Until now, the expense of cabin air monitoring has been
borne by industry, but industry is naturally resistant to making
significant new investments in cabin air monitoring equipment in the
absence of clear evidence of a related health problem. Congress has thus
far not been persuaded to fully fund a research effort of the magnitude
envisioned by NRC.

The tragic events of September 11, 2001 were not addressed by the NRC
report. However, they have raised the government and the public's
consciousness of the threat of chemical and biological (C/B) terrorism,
including the threat on board commercial airliners during flight.
Combating terrorism and increasing the safety and security of airline
passengers and crewmembers overlaps with the air quality and health
issues studied by NRC.

The Department of Defense (DOD) has invested heavily over the past
decade in new sensor technology for detecting C/B agents and in
developing miniaturized sensors. Deployment of C/B sensor technology on
commercial aircraft would open the way for onboard sensors for carbon
dioxide, carbon monoxide, and ozone as well as for human communicable
diseases. Sensor technology for C/B agents has not yet been adapted to
air quality markers, but preliminary inquiries to the scientific
community suggest that adaptation is possible.

To be fully effective, sensors for cabin environmental monitoring must
identify target agents in real time and communicate the identification
to appropriate authorities. The identification step may be integral to
the sensor device or it may be achieved by telemetry of sensor reactions
to a base station for analysis. Technology already exists that makes
these concepts feasible for cabin air monitoring.

The responses to NRC's recommendations that comprise this report
describe the actions FAA is taking to address the air quality issues
that it raised. These actions are important and necessary, but they do
not address the security issues that DOT now faces. This report serves
as a basis for achieving a much broader vision that could not have been
fully appreciated before September 11. The compelling vision of the
future that is now emerging is of a global network of surveillance
systems, operating 24 hours a day, communicating via satellite with base
stations for real-time identification of agents, data analysis, and
threat alert. If continuous monitoring for aircraft cabin contaminants
becomes a component of a global surveillance system, the problems of air
quality, disease transmission, and C/B threat could be managed
effectively to the great benefit of airliner passengers and crewmembers.

# NRC Recommendation 1 -- Air Quality Regulations

.

*FAA should rigorously demonstrate in public reports the adequacy of
current and proposed FARs related to cabin air quality and should
provide quantitative evidence and rationales to support sections of the
FARs that establish air quality-related design and operational standards
for aircraft (standards for CO, CO~2~, O~3~, ventilation, and cabin
pressure). If a specific standard is found to be inadequate to protect
the health and ensure the comfort of passengers and crew, FAA should
revise it. For ventilation, the committee recommends that an operational
standard consistent with the design standard be established.*

**Response**

NRC made several recommendations regarding air quality in the airliner
cabin environment. Its first recommendation included a general proposal
that FAA use "quantitative evidence and rationales" to support its
existing and proposed regulations related to air quality, and a specific
proposal to change the ventilation standard.

Existing FAA air quality regulatory requirements reflect a general
consensus of aircraft manufacturers that the minimum levels of CO
(carbon monoxide) and CO~2~ (carbon dioxide) are good indicators of
overall air quality. The existing design standards have assured airplane
passengers and crewmembers an acceptable cabin environment during normal
operations. In fact, the environmental control systems on board
commercial transport category airplanes provide an environment that is
equivalent to or better than that of other forms of commercial transport
when they are properly operated and maintained. Three corroborative
studies are excerpted in a Research Addendum below.

However, FAA rulemaking may not have kept pace with public expectation
and concern about air quality and does not afford explicit protection
from particulate matter and other chemical and biological hazards.

FAA concurs with the intent of NRC's recommendation and is in the
process of tasking an Aviation Rulemaking Advisory Committee (ARAC) to
review the existing standards and, if they are inadequate, to propose
revisions and/or new standards. The ARAC tasking directs its working
group to review 14CFR Part 25, §§25.831, (a) through (d) and 25.832[^1],
and to:

> Evaluate the current transport category airworthiness regulations
> regarding the airplane environment to determine if revisions are
> needed to ensure that the ventilation systems provide a suitable
> environment for crew and passengers.
>
> Assess the following issues:

-   The types of airplane system failure conditions that should be
    addressed (e.g. engine lubricant leakage, hydraulic fluid leakage,
    etc.).

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-   The types of ventilation system operating conditions that should be
    evaluated throughout the airplane's flight envelope as well as
    transient conditions (e.g., reduced ventilation rates during
    "packs-off" takeoff procedures).

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-   The appropriate ventilation rate to ensure proper control of ozone,
    carbon dioxide and carbon monoxide. The working group will also
    consider any other contaminants of concern identified by the current
    National Academy of Sciences committee on aircraft air quality.

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-   The appropriate cabin pressure altitude, humidity, and the maximum
    and minimum sustained temperature limits needed to maintain crew
    performance and crew and passenger health and comfort levels.

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-   The relevant NASA, U.S. Armed Forces, NIOSH, OSHA, FAA, and their
    respective European counterparts, academia, and industry standards
    for established concentration limits for particulates, chemical,
    biological, and other contaminants for the respective occupational
    and public health limits.

-   Recommendations of the FAA Office of Aviation (now Aerospace)
    Medicine and the National Institute of Occupational Safety and
    Health Study, the National Academy of Science investigation of
    passenger cabin air quality (scheduled for completion in FY02), the
    U.K. House of Lords, Select Committee on Science and Technology,
    5^th^ Report HL Paper 121-1, titled "Air Travel and Health,"
    published 22 November 2000; and other new European or U.S. industry
    investigations of air quality.

Without attempting to predict the outcome of the ARAC review, it appears
that the air quality regulations may evolve into a more comprehensive
standard that adopts applicable parts of an existing consensus standard
for environmental health.

**Discussion**

Present federal regulations governing the cabin environment of large
commercial transport category airplanes are found under §§25.831
(ventilation), 25.832 (cabin ozone concentration), and 25.841
(pressurized cabins). Together, the three regulations provide the
minimum standard that manufacturers of large transport category aircraft
(i.e. aircraft of more than 12,500 pounds maximum certified takeoff
weight operated by an air carrier) must meet.

The intent of §25.831 is to ensure that passengers and crewmembers have
sufficient uncontaminated air to allow reasonable comfort during normal
operating conditions and after a "probable" failure of any system that
would adversely affect the cockpit or cabin ventilation air. Of special
note are the requirements for ventilation airflow per occupant, (i.e.,
0.55 lbm per minute) and carbon monoxide. While no specific oxygen
requirement was ever specified, the 10 cfm of fresh air provides more
oxygen than is necessary for respiration while carrying out normal
activities. While the hazardous nature of CO and CO~2~ are known from
many sources, FAA selected the levels that seemed appropriate to the
airplane environment.

Section 25.832 was added in January 1980 following complaints from
crewmembers and passengers about various adverse health effects
associated with ozone in the airplane cabins. Ozone is a gas that can be
irritating to the respiratory tract and eyes when present in high enough
concentrations. Because the level of discomfort is proportional to the
level of activity of the parties exposed, cabin attendants are more
likely to be adversely affected. The ozone limits in this section are
intended to protect passengers and crewmembers from exposure to
concentrations high enough to be hazardous.

Section 25.841 provides standards for pressurized compartments in
transport category airplanes and addresses the requirements for various
controls and pressure relief valves. Testing required for demonstrating
compliance with many of the requirements of this section is addressed in
§25.843.

The ARAC rulemaking process will determine whether changes are needed in
the regulations related to air quality. It will also provide an
opportunity to address safety issues that may be related to air quality.

In 1999, FAA concluded a preliminary internal review of its event
database between January 1978 and December 1999 involving "air quality"
in the aviation Accidents and Incident Data Systems (AIDS). The review
is described in detail in the Research Addendum that follows.

Of 240 events identified in the search, about 60 were "airplane
ventilation toxic contaminant events." Of the 60 events, 24 resulted in
statements from crewmembers indicating that their performance was
impacted. In 2000, FAA broadened its investigation to include incidents
where the database included a reference to "smoke in cockpit" or "smoke
in cabin." These investigations revealed that the number of events per
flight is statistically very low. However, during some events,
crewmembers were impaired in the performance of their duties. There also
have been a number of reports of foreign airline crew members having
their performance impaired to the point that they had to be assisted in
performing their flight duties or had to relinquish their flying duties
during the flight. This is a matter of great concern to FAA.
Furthermore, during the investigation, a potential safety problem became
apparent regarding system isolation during an air contaminant event. The
ARAC working group will address this issue.

Evaluations of FAA Aviation Safety Research System reports (ASRS)
database and FAA Service Difficulty Reporting System (SDRS) database are
in progress and will be shared with the ARAC.

FAA remains concerned over the discrepancy between the number of
reported events filed in our National Aviation Safety Data Analysis
Center (NASDAC) databases and the number reported by industry
organizations. Currently, FAA only requires that a report be filed when
a direct impact on safety has occurred. Additional requirements to file
a report after an "air quality incident" will be discussed by the ARAC.

**Research Addendum**

The following research studies support FAA's position on airliner cabin
air quality.

1.  "Environmental Survey on Aircraft and Ground-Based Commercial
    Transportation Vehicles," Harvard School of Public Health, May
    31, 1997. Measurement data and information are specific to the
    Boeing 777 airplane.

> Overall, while in the air, airplanes had (except for subways) the
> lowest CO~2~ concentrations of the vehicle types. Low CO~2~
> concentrations are indicative of relatively high per-person
> ventilation, since CO~2~ is primarily derived from human occupants. On
> the other hand, relatively high CO~2~ concentrations and temperature
> during the boarding process indicate relatively low ventilation rates,
> compared to cruise periods in aircraft and to travel in other types of
> vehicles. Passengers may be exposed to these uncomfortable conditions
> for periods ranging from 30-60 minutes.
>
> In addition, concentrations of CO, NO~2~, and particles were lowest
> for aircraft, perhaps, in part, indicating the good quality of supply
> air.
>
> Humidity was also lowest for aircraft. The very low humidity during
> actual travel (cruise), compared to other transportation modes,
> results from the very low water content in supply air.
>
> Of the volatile organic compounds detected, only ethyl alcohol and
> acetone were highest in aircraft. The high ethyl alcohol levels
> probably reflect the intensive beverage service that occurs during
> cruise in aircraft. Ethyl alcohol and acetone are human effluents, and
> acetone is also used in a variety of commonly found products ....
>
> Concentrations of biological agents were generally low in aircraft
> compared to other transportation modes, outdoor air, and residential
> environments. Although geometric mean values for dust mite allergens
> were higher for airplanes than for other vehicles or homes, both mean
> and maximum levels were quite low (below levels that are considered to
> pose a risk for either sensitization or exacerbation of symptoms). Cat
> allergen levels were above the hypothetical limits for sensitization,
> but below those considered necessary to induce acute symptoms. It
> should be noted that sensitization requires chronic exposure over many
> months. It is also important to note that cat allergen is ubiquitous
> in modern environments unless specifically and rigorously excluded.

2.  "Relate Air Quality and Other Factors to Symptoms Reported by
    Passengers and Crew on Commercial Transport Category Aircraft,"
    Consolidated Safety Services, Inc., American Society of Heating,
    Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Research
    Project 957-RP, Final Report, February 1999. Measurement data and
    information are specific to the Boeing 777-200 airplane.

> The mean CO~2~ concentrations measured in this study were similar to
> levels measured by other researchers including the 1989 U.S.
> Department of Transportation study where \"measured CO~2~ levels
> averaged 1,500 ppm".
>
> Carbon dioxide levels are approximately 50% higher than the surrogate
> levels recommended in ASHRAE Standard 62-1989 for public buildings.
> However, there are no published studies that suggest the CO~2~ levels
> encountered on aircraft will result in adverse health effects. In
> fact, people are likely exposed to much higher CO~2~ levels in their
> own residences than in the aircraft. The 1,000 ppm concentration
> recommended in ASHRAE, 62-1989 is not a health hazard level, but a
> comfort level standard set to satisfy the body odor perception of 80%
> of unadapted persons (visitors) in an occupied space. Additional data
> needs to be collected on the aircraft to adequately determine what the
> CO~2~ comfort threshold is for the commercial aircraft. It appears
> however, based on the results of the data that was collected during
> this study, that the CO~2~ comfort odor threshold for aircraft will be
> higher than that of buildings, possibly around 1,500 ppm.
>
> Based on the results of this study and other studies that were
> reviewed, including the NIOSH Alaska Airlines Health Hazard
> Evaluation, harmful levels of carbon monoxide are not likely to occur
> during routine commercial aircraft operations.
>
> While harmful ozone concentrations were not recorded during this
> study, elevated ozone plumes can occur at higher altitude polar
> routes, thereby placing passengers and flight attendants that
> frequently travel these routes at an increased risk for ozone-related
> health effects.... More research concerning the health effects of
> short-term ozone exposure is needed, especially in-flight attendants
> and passengers that travel polar routes where high levels of
> atmospheric ozone are present.
>
> Exposure to harmful concentrations of volatile organic compounds
> (VOCs) does not appear to present a significant health hazard for
> passengers or flight attendants. This study, as well as other
> published and unpublished data seem to indicate that concentrations of
> total VOCs are lower on aircraft than in other public environments.
>
> This study and other studies performed to date, indicate that
> respirable suspended particulate (RSP) levels during flight are very
> low when compared with other indoor environments. There is an
> indication that elevated RSP levels (in the 200 μg/m^3^ range) are
> encountered for brief periods during boarding and deplaning. However,
> these levels are not likely high enough to present a significant
> health hazard, if one assumes that the increased levels of RSP are
> generated by passengers moving around and storing baggage and other
> personal effects. Persons with allergies to human activity allergens
> such as fabric fibers, animal dander and dust mites may experience
> symptoms similar to other crowded environments such as buses, subways,
> theaters, and auditoriums.
>
> Based on the results of this study ... and other published and
> unpublished research that was reviewed, there does not appear to be
> data supporting an increased risk of airborne disease producing
> bacteria and fungi associated with commercial airline travel. This is
> because data generally suggest that airborne levels of bacteria and
> fungi found on commercial aircraft are very low when compared with
> levels found in outdoor environments and in public buildings. Also, a
> study conducted by the Centers for Disease Control, concerning the
> transmission of Mycobacterium Tuberculosis onboard several commercial
> airline flights, concluded that it was unlikely that the organism was
> spread via the aircraft ventilation system. This is important since
> there are some researchers that contend an increase in the amount of
> outside air will lower the risk of transmission of disease producing
> bacteria and fungi. If there is an increased risk of the transmission
> of bacteria, fungi and viruses onboard commercial aircraft it is
> likely associated with the close proximity of the passengers.
> Therefore, increasing the amount of outside air will not minimize this
> type of disease transmission.
>
> Results of this study indicated the percent of oxygen onboard
> commercial aircraft remains relatively constant at approximately 21%.
> The oxygen percentage is not affected by the recirculation system due
> to the much larger supply of oxygen compared to the consumption rate.
> Obviously, the partial pressure of oxygen is reduced significantly at
> an altitude equivalent of 7,000 feet (124 mm Hg) than at sea level
> (160 mm Hg). This decrease in the partial pressure of oxygen should
> not pose a significant health hazard to healthy passengers and flight
> attendants. People with health problems that could be exasperated by
> lower oxygen pressures should consult their physician before flying.
> More data should be collected on other aircraft types to determine if
> oxygen concentrations are being maintained at a safe concentration.
>
> The relative humidity measured during the study averaged approximately
> 14% in the economy section while the aircraft was aloft. The minimum
> relative humidity recorded was 6.4% and this occurred when the
> recirculation fans were turned off (with 100% of the cabin air being
> supplied from the outside or bleed air).

3.  "HETA 90-266-2281, Alaska Airlines, Seattle, Washington," National
    Institute for Occupational Safety and Health (NIOSH) Health Hazard
    Evaluation Report, January 1993. U.S. Department of Health and Human
    Services, Public Health Service, Centers for Disease Control.
    Measurement data and information are specific to the McDonnell
    Douglas MD-80s and Boeing 727 and 737.

> Results of NIOSH environmental monitoring (continuous and grab
> measurements) aboard the \"worst case\" and \"normal\" MD-80 flights
> did not reveal a health hazard. In-flight average ranges for cabin air
> pressure (654-656 millimeters of mercury \[mm Hg\]), carbon dioxide
> (550-1191 parts per million \[ppm\]), nitrogen dioxide (not detected,
> \<2.5 ppm), oxygen (20.75-20.84%), ozone (0.005-0.017 ppm),
> temperature (74-75^o^F), total particulates (0.003-0.026 milligrams
> per cubic meter \[mg/m^3^\], and relative humidity (20-21%) were
> consistent with previous studies of commercial aircraft cabin air
> quality. The results indicated that cabin conditions commonly may not
> meet the American Society of Heating, Refrigerating and
> Air-Conditioning Engineers (ASHRAE) comfort criteria for temperature,
> relative humidity, and carbon dioxide concentrations, particularly
> during gate time. The highest instantaneous and in-flight average
> carbon dioxide concentrations, 4882 and 1191 ppm, respectively, were
> measured on the \"normal\" flight, which unintentionally had the
> longest gate time. In-flight grab sample results for carbon monoxide
> on the test flights were low (2-6 ppm), all below the ambient level of
> 9 ppm measured at Seattle/Tacoma airport. Results of direct reading
> continuous monitoring for CO were inconclusive (due to instrument
> miscalibration in the field); however, the consistent finding of
> apparent short-term peaks (5-10 ppm above baseline) indicated a
> possible source of CO exposure and the need for follow up monitoring
> (see below).
>
> Several methods were used to sample volatile organic compounds (VOCS)
> in cabin air on the test flights. Continuous in-flight monitoring with
> photoionization detectors found average total VOCs concentrations to
> be well below 10 ppm toluene equivalent (range: 1.8-3.2 ppm toluene
> equivalent). A brief, relatively high concentration peak in total VOCs
> was measured at one seat location (72-176 ppm toluene equivalent); no
> unusual events or odors were associated with the event. The major
> compound identified in sampling for VOCs was ethanol; other compounds
> found in trace (non- quantifiable) concentrations were
> cyclopentadiene, 1,1,1 trichloroethane, benzene, trichloroethylene,
> perchloroethylene, toluene, xylene isomers, siloxane compounds,
> limonene, and aliphatic compounds. No ethanol was detected in samples
> collected prior to take off (\<0.5 ppm); in-flight average
> concentrations were low, but quantifiable (range: 0.9-4.6 ppm). It is
> likely that alcoholic beverages served during the flights were the
> source. No alidehydes were detected in air samples (\<0.07 ppm).
> Neither grab air sampling method (1-liter gas bag and 50-mL evacuated
> container) tested for possible flight crew use during incidents was
> satisfactory for sampling for trace levels of VOCs.
>
> Follow up monitoring for CO was conducted by Alaska Airlines and the
> AFA (with electrochemical dosimeters) on 10 non-incident commercial
> flights, which involved nine McDonnell Douglas (MD-80s) and Boeing
> (727 and 737) aircraft, five of which had been involved in a previous
> incident. The ranges for time-weighted average (TWA) personal and area
> CO concentrations were \< 1-5 ppm (5 samples) and \< 1-7 ppm (59
> samples), respectively; all were well below the NIOSH Recommended
> Exposure Limit (REL)-TWA (adjusted for altitude) of 20 ppm.
> Corresponding instantaneous peak CO concentrations ranged from \< 1 to
> 25 ppm, all well below the NIOSH REL-Ceiling Limit of 200 ppm;
> however, the consistent finding of apparent CO peaks on commercial
> flights suggested either a common source or interference. During two
> additional non-incident commercial flights, NIOSH investigators
> conducted monitoring for CO using paired sealed and unsealed
> dosimeters, and a laboratory-based grab sampling method. The results
> indicated that a CO peak measured with a dosimeter (30-35 ppm) was due
> to an interfering gas or vapor.

4.  In 1999, FAA concluded a preliminary internal review of events
    involving "air quality" in the aviation Accidents and Incident Data
    Systems (AIDS) database. The database is part of FAA National
    Aviation Safety Data Analysis Center (NASDAC) database and it
    contains data records for general aviation and air carrier incidents
    that do not meet the damage or injury thresholds of the National
    Transportation Safety Board (NTSB) definition of an accident. The
    search was conducted on *Air Carrier/Commercial* operations within
    the United States between January 1978 and December 1999 using the
    search string: odor, fume, gas, smell.

> The 240 events identified in the search included, as the largest group
> of events, 144 in the category of "electrical failure" (i.e.,
> recirculation fan failures, electrical component failures, arcing of
> wires, etc.). Approximately 60 events were "airplane ventilation toxic
> contaminant events," where failures occurred in airplane, engine, or
> auxiliary power unit (APU) systems that may have caused tri-cresyl
> phosphate lubricants, or phosphate ester hydraulic fluids, or products
> of decomposition from these fluids to enter the cockpit/cabin
> ventilation systems. Of these 60 events, approximately 24 resulted in
> statements from crewmembers indicating that their performance was
> impaired.
>
> To put the number of events in proper context, it is necessary to
> relate it to the number of airplane departures and/or flight hours.
> Using reported data from 1989 through 1996 and a linear extrapolation
> to estimate data for 1997, 1998 and 1999, from January 1989 through
> December 1999 there were approximately 82,570,744 departures with a
> total accumulated aircraft hours of 121,241,680. An AIDS search over
> the same period identified a total of 167 events of which
> approximately 14% were connected to air contaminants present in the
> ventilation system. These results indicate a likelihood of an event
> occurring as 0.000000278 per departure, or 0.000000189 per aircraft
> hour.
>
> In 2000, FAA broadened its investigation by conducting a search of the
> database using the search string: "smoke in cockpit," "smoke in
> cabin," odor, fume, gas, smell. The search was conducted on *Air
> Carrier/Commercial* operations within the United States between
> January 1978 and December 1999 and resulted in a match with
> approximately 416 events. The result of that search appears in Tables
> 1-3. The numbers of occurrences are given per an indicator of root
> cause (i.e., the failure that led to the event). In addition, Figure 1
> shows the breakdown per general system failure. To put these events
> into perspective, actual data on the total number of aircraft hours
> originating from U.S. airports from 1987 through 1996 was used. The
> total number of "air quality" events during this period was
> approximately 222; the total number of aircraft hours was 100,551,114.
> The likelihood of an "air quality" event occurring on a large
> commercial transport airplane was 0.00000221 per aircraft hour or 2.2
> events every 1,000,000 aircraft hours. Because there is currently no
> requirement that crewmembers report "air quality" events, however,
> these numbers may understate actual occurrences.
>
> **Table 1: FAA AIDS Results from 1991 through 1999 for all Air Carrier
> Part 121**
>
> **US Airplanes; Search String: "smoke in cockpit", odor, fume, vapor,
> smell, gas**

![](media/image2.wmf)

> **Table 2: FAA AIDS Results from 1982 through 1990 for all Air Carrier
> Part 121**
>
> **US Airplanes; Search String: "smoke in cockpit", odor, fume, vapor,
> smell, gas**
>
> ![](media/image3.wmf)
>
> **Table 3: FAA AIDS Results from 1978 through 1981 for all Air Carrier
> Part 121**
>
> **US Airplanes; Search String: "smoke in cockpit", odor, fume, vapor,
> smell, gas**

![](media/image4.wmf)

![](media/image5.wmf){width="4.0in"
height="2.329861111111111in"}**Figure 1: Sources of "smoke in cockpit",
odor, fume, vapor, smell, gas**

**in the cabin or cockpit; 1978 through 1999**

# NRC Recommendation 2 -- Regulations for Ozone

FAA should take effective measures to ensure that the current FAR for
O~3~ (average concentrations not to exceed 0.1 ppm above 27,000 ft, and
peak concentrations not to exceed 0.25 ppm above 32,000 ft) is met on
all flights, regardless of altitude. These measures should include a
requirement that either O~3~ converters be installed, used, and
maintained on all aircraft capable of flying at or above those
altitudes, or strict operating limits be set with regard to altitudes
and routes for aircraft without converters to ensure that the O~3~
concentrations are not exceeded in reasonable worst-case scenarios. To
ensure compliance with the O~3~ requirements, FAA should conduct
monitoring to verify that the O~3~ controls are operating properly (see
also recommendation 8).

**Response**

NRC recommended that FAA ensure that existing regulations regarding O~3~
(ozone) concentration are met by mandating the use of ozone converters
or prohibiting flights above 25,000 feet (i.e., below the minimum
altitude applicable for existing rules.).

FAA concurs with the intent of the recommendation as an appropriate and
measured response to the potential of new airplanes to cruise at higher
altitudes and to changes in the atmospheric composition of trace gases.
As noted under the response to NRC's Recommendation 1, FAA is in the
process of tasking an ARAC to review the existing standards and, if they
are inadequate, to propose revisions and/or new standards. The ARAC
tasking directs its working group to review 14CFR Part 25, §§25.831(a)
through (d) and 25.832, and to:

> Evaluate the current transport category airworthiness regulations
> regarding the airplane environment to determine if revisions are
> needed to ensure that the ventilation systems provide a suitable
> environment for crew and passengers.
>
> Assess the following issues:

-   The appropriate ventilation rate to ensure proper control of ozone,
    carbon dioxide and carbon monoxide.

> The working group will also consider any other contaminants of concern
> identified by the current National Academy of Sciences committee on
> aircraft air quality.

The ARAC review also will address design mitigation strategy and means
of compliance. Without attempting to predict the outcome of the review,
it appears that an ozone converter (i.e., a device that removes ozone
from the air) on large transport category airplanes may be the most
robust methodology to ensure consistent, successful compliance with
regulations governing airplane ozone control.

**Discussion**

Ozone is a gas that can be irritating to the respiratory tract and eyes
when present in high enough concentrations. The existing Federal
Aviation Regulations governing ozone in the airplane cabins is 14CFR
§25.832. There is a parallel requirement in the operating rules
(§121.578). The regulation was adopted in January 1980 after complaints
and a petition for rulemaking by crewmembers and passengers. The
objective of the rule is to protect cabin occupants from various adverse
health effects associated with ozone in the cabin environment by setting
maximum standards for concentrations of ozone in the occupied areas of
transport category airplanes.

Although the results of two relevant studies (quoted in the Research
Addendum below) have shown that ozone concentration does not represent a
threat to the occupants of large transport category airplanes,
additional research may be needed. FAA's regulatory guidance material
regarding ozone concentration[^2] was developed in the 1960's and 70's.
Information from NASA[^3] indicates that the ozone content and
distribution have changed significantly since then. In addition, future
airplanes will be able to cruise at higher altitudes in the stratosphere
where the concentration of external ozone is much higher than in the
troposphere.[^4]

**Research Addendum**

1.  "HETA 90-266-2281, Alaska Airlines, Seattle, Washington," National
    Institute for Occupational Safety and Health (NIOSH) Health Hazard
    Evaluation Report, January 1993. U.S. Department of Health and Human
    Services, Public Health Service, Centers for Disease Control.
    Measurement data and information are specific to the McDonnell
    Douglas MD-80s and Boeing 727 and 737.

> Results of NIOSH environmental monitoring (continuous and grab
> measurements) aboard the \"worst case\" and \"normal\" MD-80 flights
> did not reveal a health hazard. In-flight average ranges for cabin air
> pressure (654-656 millimeters of mercury \[mm Hg\]) ... ozone
> (0.005-0.017 ppm) ...were consistent with previous studies of
> commercial aircraft cabin air quality.

2.  "Relate Air Quality and Other Factors to Symptoms Reported by
    Passengers and Crew on Commercial Transport Category Aircraft",
    Consolidated Safety Services, Inc., American Society of Heating,
    Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Research
    Project 957-RP, Final Report, February 1999. Measurement data and
    information are specific to the Boeing 777-200.

> Continuous ozone (O~3~) measurements were collected using a
> direct-reading, electrochemical sensor, with measurements averaged
> every five minutes.... The mean O~3~ level for all flights while the
> aircraft was aloft was 51 ppb \[parts per billion by volume\]. The
> mean concentration for domestic flights was 46 ppb, while the mean
> level for international flights was 53 ppb. The mean concentration was
> higher on the ground, 62 ppb during boarding and 77 ppb during
> deplaning, than when the aircraft was aloft. The highest five-minute
> mean recorded was 122 ppb during an international flight between
> Washington and London. Of the 287 five-minute mean periods that were
> recorded when the aircraft was aloft, 100 ppb was only met or exceeded
> during nine periods. \[The accuracy of the ozone sensor was plus or
> minus 100 ppb, therefore these results cannot be considered
> conclusive.)"
>
> Analysis of the symptoms data collected from the comfort questionnaire
> indicated that passengers did not significantly experience
> ozone-related health symptoms. For example, shortness of breath and
> dizziness, two symptoms often associated with ozone exposure were the
> two symptoms least experienced by passengers, 4.7% and 5.7%,
> respectively. Other symptoms associated with ozone exposure (e.g.
> headache; dry itchy or irritated eyes; and sore, dry throat) were
> reported more frequently however, these symptoms can also be caused by
> other confounding factors such as low humidity.

# NRC Recommendation 3 -- Air Cleaning Equipment

*FAA should investigate and publicly report on the need for and
feasibility of installing air-cleaning equipment for removing particles
and vapors from the air supplied by the ECS \[environmental control
system\] on all aircraft to prevent or minimize the introduction of
contaminants into the passenger cabin during ground operation, normal
flight, and air quality incidents*.

**Response**

NRC recommended that FAA investigate the need for particulate filters
and gaseous filtration systems on all aircraft. FAA concurs with the
intent of NRC's recommendation and is in the process of tasking an ARAC
to review the existing standards and, if they are found to be
inadequate, to propose new standards. The ARAC tasking directs its
working group to review 14CFR Part 25, §§25.831(a) through (d) and
25.832, and to:

> Evaluate the current transport category airworthiness regulations
> regarding the airplane environment to determine if revisions are
> needed to ensure that the ventilation systems provide a suitable
> environment for crew and passengers.
>
> Assess the following issues:

-   The appropriate filtration and monitoring mechanisms to provide
    suitable cabin air quality. Odors, chemical and biological
    contaminants (bio-aerosols), particulates, and other contaminants
    should be included in the review to ensure that sufficient design
    safeguards exist such that any contaminants present do not reach a
    concentration which would impact crew performance, disable any
    passenger, or create long term health problems in passengers or
    crew.

Without attempting to predict the outcome of the ARAC review, FAA
anticipates that the regulations governing airplane air quality may
evolve into a more comprehensive standard based on applicable parts of
an existing consensus standard for environmental health that includes a
maximum level of particulate and gaseous contaminants.

**Discussion**

Section 25.831 established standards for the quantity of fresh air to be
provided per occupant of an airplane cabin and the maximum amount of
carbon dioxide and carbon monoxide gas that can be present. Section
25.832 established the maximum amount of ozone that can be present.
Section 25.841 established standards for the pressurized compartments in
all transport category airplanes. None of these regulations require the
airplane manufacturer to incorporate a particulate filtration system or
gaseous adsorption system into the environmental control system.

Manufacturers of most new airplanes incorporate either High Efficiency
Particulate Air (HEPA) filters (rated at 99.97% removal efficiency for
0.3 μm particles) or particulate filters that are somewhat less
efficient (rated at 97-99.5% removal efficiency for 0.3 μm particles) at
the request of their customers. Several airlines have installed HEPA
filters on board airplanes that did not originally incorporate them in
their design. Others are experimenting with the use of gaseous
adsorption systems onboard large commercial airplanes, but no large
transport category airplane is routinely manufactured with these systems
installed.

# NRC Recommendation 4 -- Carbon Monoxide Monitoring

FAA should require a CO monitor in the air supply ducts to passenger
cabins and establish standard operating procedures for responding to
elevated CO concentrations.

**Response**

NRC recommended that FAA mandate the installation of a CO (carbon
monoxide) monitoring system and that it establish flight crew procedures
for responding to elevated CO. The text of its report included four
related recommendations that suggest that NRC envisioned a more
comprehensive air quality monitoring system:

-   Because CO is most likely produced during air quality incidents
    involving leaks of engine lubricating oils or hydraulic fluids in
    the ECS, it should be monitored in the ducts that introduce air into
    the cabin or cockpit.

-   More research should be conducted to determine products that might
    be generated when engine lubricating oils, hydraulic fluids, and
    deicing fluids are exposed to high temperatures that might be
    encountered in the ECS.

-   Instruments for monitoring O~3~, CO, and CO~2~, temperature, cabin
    pressure, relative humidity, and particulate material (PM) should be
    used in the surveillance or research investigations aboard
    commercial aircraft as described in Chapter 8 (of the NRC report).

-   Routine surveillance of a number of air quality characteristics
    (O~3~, CO and CO~2~, fine PM, cabin pressure, relative humidity and
    temperature) should be implemented in a continuing program to
    characterize the range of air quality found in aircraft.

As noted in the response to NRC's Recommendation 1, FAA supports the
development of a system that would alert the crew to the presence of an
air contaminant. It also agrees that research is needed regarding the
products of pyrolysis associated with hydraulic fluids, engine oils, and
lubricants. The need for monitoring for the air quality characteristics
noted above may result from the research initiatives outlined in the
response to NRC's Recommendations 9 and 10. For FAA, the flight crew's
response to an "air contaminant" event is a more important concern than
CO monitoring. It envisions a system that will ensure that the flight
crew is aware of an "air contaminant" event and will identify the
source. FAA concurs with the need for a warning and it communicated this
to NRC during its study. However, CO may not be the correct or the only
contaminant to "trigger" on.

As noted above, FAA is tasking an ARAC to review the existing standards
and, if they are found to be inadequate, to propose new standards. The
ARAC tasking directs its working group to review 14CFR Part 25,
§§25.831(a) through (d) and 25.832, and to:

> Evaluate the current transport category airworthiness regulations
> regarding the airplane environment to determine if revisions are
> needed to ensure that the ventilation systems provide a suitable
> environment for crew and passengers.
>
> Assess the following issues:

-   The appropriate filtration and monitoring mechanisms to provide
    suitable cabin air quality. Odors, chemical and biological
    contaminants (bio-aerosols), particulates and other contaminants
    should be included in the review to ensure that sufficient design
    safeguards exist such that any contaminants present do not reach a
    concentration which would impact crew performance, disable any
    passenger, or create long term health problems in passengers or
    crew.

While it would be inappropriate to predict the outcome of the ARAC's
deliberations, FAA believes that the regulations governing airplane air
quality will evolve into the adoption of a requirement that the airplane
be designed with features which enable the flight deck crewmembers to
successfully isolate system failures. Such a system would discriminate
between "normal" and "abnormal" levels of certain types of gaseous
agents, chemicals and bioaerosols. It may be feasible to incorporate a
dual monitoring system that continuously measures background levels as
well as the unusual "spikes" that indicate the presence of a
contaminant. However some contaminant hazards may require unique
monitoring instruments.

**Discussion**

The existing Federal Aviation Regulations governing the cabin
environment onboard large transport category airplanes are contained in
14CFR §§25.831, 25.832, and 25.841.

Section 25.831 intends that passengers and crewmembers have enough
uncontaminated air to provide reasonable comfort during normal operating
conditions and also after any probable failure (i.e. failure conditions
with a probability of 1 x 10^-5^ or greater) of any system that would
adversely affect the cockpit or cabin ventilation air. FAA's
interpretation of the regulation has always been restricted to
compliance with ventilation, CO or CO~2~. There is no requirement for
the presence of a system to monitor cabin "air quality" (i.e., O~3~, CO
and CO~2~, temperature, cabin pressure, relative humidity, and
particulate material, as discussed by NRC).

Available data do not suggest that a continuously operated air quality
monitoring system will add significant benefit for passengers and crews,
especially relative to the added cost. As communicated to NRC, FAA has
never required an air quality monitoring system that provides a warning
to the crew that an air contaminant is present. FAA's internal review
has shown that air quality events or failures that impact cabin air
quality are highly improbable (i.e., between 10^-5^ and 10^-7^). FAA is
searching its databases to determine the number of air contaminant
events.

However, there have been a number of serious incidents in Australia,
Europe and Canada in which pilots have become incapacitated during a
flight because of suspected air contaminants. It is not clear whether a
CO monitor would have been sufficient to detect the presence of the
contaminant. FAA believes that there may be other chemicals or a broader
set of hazards, including biohazards, that should be monitored. FAA is
aware that some manufacturers are pursuing the development of bleed air
monitors to provide real-time notification of the presence of air
contaminants to the flight crew to enable enhanced failure isolation
procedures. Currently, no large transport category airplane is routinely
manufactured with these systems installed.

FAA is aware that several airlines are experimenting with the use of
gaseous adsorption for some types and quantities of contaminants.
Gaseous adsorption would fail to provide protection for massive
quantities of contaminants. Currently, no large transport category
airplane is routinely manufactured with these systems installed.

All existing commercial transport category airplanes have procedures in
their airplane flight manuals to follow in the event of smoke or an
unknown contaminant or smell in the cockpit. These typically require the
flight crew to don oxygen masks and attempt to isolate the source.
However, currently, no commercial transport category airplane
incorporates a monitoring system that informs the crew when an air
contaminant is present or enables the flight deck crewmembers to know
the exact location of the contaminant's introduction into the system. As
noted above, the issue of air contaminant isolation will be included in
FAA rulemaking activities.

# NRC Recommendation 5 -- Allergens 

Because of the potential for serious health effects related to exposures
of sensitive people to allergens, the need to prohibit transport of
small animals in aircraft cabins should be investigated, and cabin crews
should be trained to recognize and respond to severe, potentially
life-threatening responses (e.g., anaphylaxis, severe asthma attacks)
that hypersensitive people might experience because of exposure to
airborne allergens.

#  

**Response**

NRC, in response to concerns about health risks to airline passengers
who are sensitive to allergens, recommended an investigation to
determine if small animals should be prohibited in airplane cabins. It
also recommended that cabin crews be trained to recognize and respond to
severe reactions to airborne allergens.

Allergens in the airplane cabin are a serious, potentially
life-threatening, issue for a small segment of the airline passenger
population. FAA will take several actions to address this area of
concern. It will issue an Advisory Circular that incorporates the most
effective industry practices regarding passenger handling procedures for
allergen-sensitive people seated close to animals. The circular also
will address the importance of crewmember training in recognizing and
responding to in-flight medical events that result from allergen
exposure.

In addition, every effort will be made to ensure that flight attendants
and the aviation community in general have the most up to date
information for the treatment of allergen-related medical events. This
information will complement existing FAA regulations and guidance
specific to flight attendant training regarding the response to severe
allergic reactions. FAA guidance on this area of flight attendant
training is also contained in Advisory Circular 120-44A, Air Carrier
First Aid Programs.

Vehicles for disseminating information on allergen related events would
include:

-   FAA's Civil Aerospace Medical Institute (CAMI) Cabin Safety Workshop
    for flight attendants

-   A CAMI web site that will be established (see the response to NRC's
    Recommendation 6, below)

-   The Department of Transportation (DOT), Aviation Consumer Protection
    Division's web site that provides safety and security information

-   The Flight Standards Service web site

Information currently provided on DOT and FAA web sites about pets and
service animals will be enhanced to include FAA policy on the carriage
of animals in the cabin, the policies of air carriers, including those
that do not allow animals in the cabin, and additional sources of
consumer information.

As part of the surveillance and research efforts described in
Recommendations 8 and 9, the data collection forms now used in the
in-flight medical event program will be evaluated to ensure optimum
coverage of allergen-related medical problems. The program also will be
enhanced to include as many airlines as possible.

Responding to allergen-related medical events such as anaphylaxis and
asthma attacks may require the use of the regulatory-mandated in-flight
emergency medical kit. FAA published a final rule on Emergency Medical
Equipment on April 12, 2001 which required automated external
defibrillators on large passenger-carrying aircraft as well as
enhancements to the emergency medical kits, including a bronchodilator
inhaler and additional epinephrine. Under §121.805, crewmembers must
receive instruction in emergency medical event procedures as well as
instruction that will familiarize them with the contents of the
emergency medical kit.

With regard to NRC's recommendation regarding the prohibition of animals
in the cabin, FAA does not believe a regulatory action in this area is
warranted. Currently, air carriers formulate their own policies and
procedures pertaining to animals in the cabin. The Air Carrier Access
Act (ACAA)[^5] rules require that dogs and other service animals be
allowed to accompany passengers with disabilities in the airline cabin.
Prohibiting animals will not completely eliminate the exposure of
sensitive passengers to allergens introduced from other sources,
including passenger clothing, in the cabin environment. Animal dander
typically remains localized near the animal for the duration of the
flight because of zonal airflow within the cabin and the industry's
increasing use of HEPA filters in the cabin ventilation systems.

**Discussion**

A review of the major airlines found that they all have procedures
related to the carriage of animals in the cabin and that existing
procedures are fairly standard among air carriers. Conditions of
acceptance of animals in the cabin typically include:

-   A list of animals that would be accepted for transport

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-   A limit on the number of animals in the cabin

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-   A limit on the number of animals that may accompany one passenger

-   A requirement that the animal be harmless, inoffensive and odorless

-   A requirement that the animal be confined in a container or cage
    that fits completely under the seat

-   A requirement that the passenger be able to produce a health
    certificate issued within 30 days of originating travel

Typical flight attendant procedures to address passenger concern include
reseating the passenger with the animal away from an allergen-sensitive
passenger or coordinating with customer service personnel to offer
another flight to the passenger with the animal. At present, one major
airline does not accept animals for transportation in the aircraft
cabin, except for service animals trained to assist persons with
disabilities. Present FAA regulations[^6] and guidance specific to
flight attendant training address recognition and response to the severe
allergic reactions that hypersensitive passengers might experience
because of the presence of allergens on the aircraft.

The literature reviewed in NRC's report supports its concern about
animal allergens in airliner cabins. However, another recent study[^7]
found that, although dog and cat allergens were present in public
transportation vehicles at levels that can cause symptoms in sensitive
persons, prohibiting them probably would bring only a modest reduction
in allergen levels because much of the allergen contamination that is
present in the aircraft cabin is carried in on the clothes of other
passengers.

Additional information is available from the CAMI through its
collaboration with Medaire®, an industry provider of in-flight medical
support. A study[^8] based on 1996-97 data on passenger and crew medical
events that resulted in a call to Medaire for support covered about 20%
of U.S. airline passengers. The study showed that 2.4% of the in-flight
medical events were allergic events. There were no deaths in this
category of in-flight medical events and no mention of animals in the
cabin. The data are from actual in-flight medical events and is not
likely to have excluded serious cases of allergy. If the study is
repeated in the future, it will benefit from a much larger (\~50%) level
of airline industry participation.

The Allergy and Respiratory categories were searched to evaluate the
past history of reported problems with allergens. When searched for
allergy, no cases specifically mentioned animals as the cause of the
allergic reaction. Specific mention was made of shellfish (2), insect
bite (1), peanut allergic reaction (1), egg allergic reaction (1), drug
reaction (1), and allergy shot reaction (1).

In the Allergy data set (n=27), the emergency medical kit was used about
half the time (13 out of 27 events). Oxygen was used in 4 of the 27
events. In the Respiratory data set (n=92), 8 of the 92 events were
identified as asthma. No cases specifically mentioned animal allergy as
the cause of the respiratory condition and no deaths were reported. The
Respiratory data set included one case of a passenger who choked on a
peanut, but not due to allergy.

The emergency medical kit was not used in 48 of the 92 events; it was
used in 39; its use was not specified in 5. Oxygen was used 83 of the 92
events (90%). Epinephrine was used 1 time in an asthma case listed in
the respiratory category. Benzodiazepine was used 1 time. Bronchodilator
was used in 14 of 92 events (15%). Oral antihistamine was used 2 times
and injectable diphenhydramine was not used in any of the 92 events.

# NRC Recommendation 6 -- Health Information 

Increased efforts should be made to provide cabin crew, passengers, and
health professionals with information on health issues related to air
travel. To that end, FAA and the airlines should work with such
organizations as the American Medical Association and the Aerospace
Medical Association to improve health professionals' awareness of the
need to advise patients on the potential risks of flying, including
risks associated with decreased cabin pressure, flying with active
infections, increased susceptibility to infection or hypersensitivity.

**Response**

NRC recommended increased efforts to provide cabin crew, passengers, and
health professionals with information on health issues related to air
travel, and especially on the potential risks of flying. This effort
should be a collaborative one that includes airlines and professional
medical organizations such as the American Medical Association and the
Aerospace Medical Association.

FAA concurs with NRC's recommendation and will continue to focus the
attention of its Office of Aerospace Medicine on potential health issues
and problems for healthy passengers, for passengers with a variety of
medical problems, and for crewmembers. In addition, it will increase its
efforts to make available information and recommendations on air travel
health and medical issues through a web site that is accessible to the
general public.

FAA's Office of Aerospace Medicine has established and will continue to
enhance a readily accessible portion of the CAMI web site to provide
appropriate health and medical information and recommendations that is
as up-to-date as possible. This will include research findings and other
information that becomes available as a result of activities that
develop from NRC's Recommendations 8 and 9. Based on data from the
surveillance and research programs, special groups such as young and
elderly passengers and patient populations that have unique
predisposition to problems in the civilian aviation environment would be
identified and informed of the risks associated with air travel.

**Discussion**

The Aerospace Medical Association has developed general medical
guidelines for passengers in civilian aviation. The American College of
Obstetricians and Gynecologists Committee on Obstetric Practice recently
developed and published recommendations concerning air travel during
pregnancy[^9]. Similar recommendations from other medical specialties
should be readily available and accessible in the up-to-date form to all
medical professionals, aviation passengers and crewmembers, and the
general public.

CAMI conducts seminars and other training activities for Aviation
Medical Examiners (AMEs) that include discussion of health issues in
civil aviation operations. The AME courses are oriented to the
professional health care provider and medical certification of airmen
and provide an opportunity to communicate with over 4,500 health care
providers. These professionals represent a significant asset for
providing health-related information to aviators and the flying public.
CAMI produces aeromedical publications that, in the future, will include
coverage of more health issues. New educational outreach activities and
instructional tools (such as brochures, videos, and web page
information) will be developed by the Aeromedical Education Division at
CAMI to provide cabin crew, passengers, and health care providers with
information regarding health issues in civil aviation. Adequate
distribution of the material will depend on the availability of
additional resources.

In addition to the seminars and training for AMEs, the CAMI Aeromedical
Education Division provides courses in aviation physiology and global
survival. These training programs for aviation professionals may be used
as a conduit for passenger and cabin safety information. The CAMI
Aeromedical Education Division also provides seminars and demonstrations
at numerous air-shows and aviation-related events. While these events
are generally attended by aviation professionals and general aviation
pilots and owners, information on passenger and cabin safety that is of
interest to the general public is also disseminated. The CAMI
Aeromedical Research Division conducts a Cabin Safety Workshop that is
oriented toward cabin safety and flight attendant issues. The workshop
provides current information and practical training on cabin evacuation,
biodynamics, altitude, recent accidents and general cabin safety
information. These training programs transmit information to the flying
public both directly and indirectly.

As noted above, DOT's Aviation Consumer Protection Division maintains a
web site that provides safety and security information and acts as a
focal point for consumer problems and complaints. The Assistant
Secretary for Transportation Policy maintains a web site on smoking and
disinsection policies of airlines and countries. The Office of the
Secretary of Transportation and FAA provide information regarding
traveling with animals or service animals and guidance for passengers
with special travel requirements (oxygen bottles, wheel chairs, other
support needs).

# NRC Recommendation 7 -- Ventilation Shutdown 

The committee reiterates the recommendation of the 1986 NRC report that
a regulation be established to require removal of passengers from an
aircraft within 30 minutes after a ventilation failure or shutdown on
the ground and to ensure the maintenance of full ventilation whenever
on-board or ground-based air conditioning is available.

**Response**

NRC repeated its 1986 recommendation that a regulation be established to
require air carriers to remove all passengers from an aircraft within 30
minutes after a ventilation failure or shutdown on the ground and also
require air carriers to use full ventilation on the ground whenever
on-board or ground-based air conditioning is available.

FAA concurs with the objective of the recommendation. It will issue an
Advisory Circular to expand its guidance to all air carriers regarding
the need to maintain full ventilation whenever onboard or ground
air-conditioning is available and the need to deplane passengers within
30 minutes after a ventilation failure or shutdown on the ground, when
possible.

This guidance will include a statement of the problem, background
information, and a discussion of all relevant issues and operational
considerations that may impact an air carrier's decision to deplane
passengers. NRC's recommendation was based on a concern about the spread
of disease among passengers when forced air ventilation is not available
on the ground. However, FAA also is aware that there may be other
issues, including safety, job performance, and comfort of passengers and
crewmembers who are required to remain onboard an aircraft on the ground
during a ventilation failure or shutdown.

**Discussion**

The original recommendation in the 1986 NRC report was based on
information regarding a 1977 outbreak of influenza among passengers and
crew exposed to a passenger in the early stages of influenza. The
aircraft was on the ground for several hours undergoing maintenance and
the ventilation system was inoperative while repairs were attempted. The
passengers who were onboard the aircraft were given a choice whether to
remain onboard or return to the terminal. Of those passengers who
elected to remain onboard, which included the passenger with influenza,
a majority was inflicted with influenza in varying degrees of severity
within a few days. None of the passengers who elected to wait in the
terminal and then continue the flight on a substitute, normally
ventilated aircraft, contracted influenza.

NRC concluded that proper operation of the air circulation equipment
might have prevented the outbreak of influenza. It recommended in 1986
and again in 2001 that, during passenger operations, when ventilation
could not be maintained on any aircraft on the ground, all passengers
must be deplaned within 30 minutes or less from ventilation failure or
shut down.

The 1986 NRC recommendation was as follows:

> Because a likelihood of occurrence of epidemic disease when forced air
> ventilation is not available on the ground has been demonstrated, the
> Committee recommends that a regulation be established that requires
> removal of passengers from an airplane within 30 minutes or less after
> a ventilation failure or shutdown on the ground and maintenance of
> full ventilation whenever onboard or ground air-conditioning is
> available.

The response to this recommendation stated in part:

> DOT agrees that confinement in an unventilated enclosure (room, car,
> bus, etc.) will facilitate spread of epidemic disease. Because the
> occurrence of complete ventilation cessation on passenger-laden
> airplanes is extremely rare.... we do not believe that regulatory
> action is necessary....
>
> Planned Action
>
> While the risk of occurrence of complete ventilation cessation on
> passenger-laden airplanes is extremely low, we believe that there may
> be value in bringing this concern to the attention of the air
> carriers. FAA will advise air carriers of the need to deplane
> passengers, if possible, after thirty minutes without ventilation.

An Action Notice to FAA Inspectors on "Passenger Handling During Ground
Operations with No Cabin Ventilation" was issued on October 19, 1987 and
was in effect through October 1988. In the Action Notice and its 1987
response to Congress, FAA interpreted NRC's recommendation to require
removal of all passengers, if possible, after thirty minutes without
ventilation. FAA's current understanding of the recommendation, based on
clarifying information in NRC's report, is that the removal of
passengers from an airplane must be completed within 30 minutes after a
ventilation failure or shutdown on the ground.

# NRC Recommendation 8 -- Surveillance Program

To be consistent with FAA's mission to promote aviation safety, an air
quality and health surveillance program should be established. The
objectives and approaches of this program are summarized in Table S-2.
The health and air quality components should be coordinated so that the
data are collected in a manner that allows analysis of the suggested
relationship between health effects or complaints and cabin air quality.

> **Table S-2 Surveillance and Research Programs**
>
> [Surveillance Program Objectives]{.underline}

-   To determine aircraft compliance with existing FAR\'s for air
    quality

-   To characterize accurately air quality and establish temporal trends
    of air quality characteristics in a broad sample of representative
    aircraft

-   To estimate the frequency of non-routine operations in which serious
    degradation of cabin air quality occurs

-   To document systematically health effects or complaints of
    passengers and crew related to routine conditions of flight or air
    quality incidents; to be effective, this effort must be conducted
    and coordinated in conjunction with air quality monitoring

> [Surveillance Program Approach]{.underline}

-   Continuously monitor and record O~3~, CO, CO~2~, fine particles,
    cabin pressure, temperature, and relative humidity

-   Sample a representative number of flights over a period of 1-2 years

-   Continue to monitor flights to ensure accurate characterization of
    air quality as new aircraft come online and aircraft equipment ages
    or is upgraded

-   Conduct a program for the systematic collection, analysis, and
    reporting of health data with the cabin crew as the primary study
    group

**Response**

NRC recommended that FAA establish a surveillance program for both air
quality and health. The program's objectives and approaches are
summarized in Table S-2, Surveillance and Research Programs. The
components of the surveillance program are to be coordinated so that the
data collected allows analysis of the suggested relationship between
health effects or complaints and cabin air quality. The proposed air
quality and health surveillance is to be linked closely to NRC's
Recommendation 9 that covers a broad range of potential research
efforts. Data gathered from the proposed surveillance effort could be
used to help define the scope of the research effort. FAA concurs with
the intent of NRC's recommendation.

NRC's report correctly linked its research proposal with a health
effects survey effort and suggested that they both should be addressed
by the agency that is designated to lead the research project. NRC
proposed that the NIOSH air sampling and health effects survey projects
be reviewed to determine their applicability to the proposed research
effort. The NIOSH effort has developed the sampling capability and
survey procedures to conduct a preliminary study. Similarly, the lead
research organization should review all available data to develop
procedures that could accurately define the frequency of non-routine air
quality incidents and determine if and what after-the-fact investigation
procedures could be implemented. Combined government, industry, and
union participation will be critical to the success for the effort.

**Discussion**

As required by FAA Authorization Act,[^10] FAA contracted with the
Centers for Disease Control and Prevention, National Institute for
Occupational Safety and Health (NIOSH) to conduct a study to
characterize and identify potential health issues related to the
aircraft cabin environment. A preliminary study established a
surveillance program to continuously monitor and record seven cabin air
quality parameters: ozone (O~3)~, carbon monoxide (CO), carbon dioxide
(CO~2~), fine particles that are less than 10 micrometers in diameter
(PM ~10~), cabin atmospheric pressures, dry bulb temperatures, and
relative humidity. These and additional parameters were monitored by
NIOSH over two years on 33 commercial flights on ten different types of
airplanes owned by four air carriers. NIOSH was also directed to conduct
a health effects survey of female flight attendants that initially
focused on reproductive health, and was later expanded to include
respiratory effects. The respiratory effects survey included a generally
non-flying comparison group of teachers. The study addresses respiratory
symptomatology (both infectious and noninfectious etiology), flight
history data, and lifestyle factors. The study did not include direct
linkage to measurement of cabin environment conditions. The survey
respondents flew on a wide variety of aircraft in which the cabin
environment was not sampled.

The process established in this research effort provides a starting
point for the development of a longer-term surveillance and health
effects assessment that could meet some of NRC's recommendations for
routine flights. With the cooperation and coordination of the airlines,
flight attendants and other parties, a health effects survey could be
used on a small number of monitored flights (NRC's report suggests 100
flights) to support linkage of air quality sampling and comfort and
health effects.

Surveillance to identify the potential cabin air contaminants and their
potential health effects during non-routine, air quality system events
is a more complex and difficult issue. As part of the surveillance
program, NRC suggests that methods be developed or utilized to estimate
the frequency of non-routine operations in which serious degradation of
cabin air quality occurs. As discussed under Recommendation 1, available
data suggest that air quality system failures are extremely rare events.
This was recognized by NRC's statement in Chapter 8 that sampling the
number of flights necessary to gain valid air quality data during
non-routine flights "is not feasible." Chapter 8 provided a number of
suggestions on how to identify potential air quality incidents and
establish a monitoring regimen. These suggestions include "ad-hoc" air
sampling and a health effects survey or interview to be conducted
following a potential air quality incident. FAA could provide some
laboratory analytical support for the ad hoc sampling program. However,
gathering data on-site and completing health effects surveys or
interviews would require industry or other agency participation as would
any medical follow up. The other NRC suggestions on how to isolate
non-routine air quality events include review of aircraft maintenance
records, focusing on "problem aircraft," analysis of contaminants in air
filtration systems, and investigation of only aircraft or flights which
have reported problems. Each of these areas will require further
investigation by both government and industry to determine feasibility
and potential effectiveness. It must be noted that while the
identification of air quality incidents and air sampling may be improved
by a number of methods, the health effects information from surveys and
interviews will remain primarily subjective.

# NRC Recommendation 9 -- Research Program

To answer specific questions about cabin air quality, a research program
should be established (see Table S-2). The committee considers the
following research questions to be of high priority:

-   O~3~. How is the O~3~ concentration in the cabin environment
    affected by various factors (e.g., ambient concentrations, reaction
    with surfaces, the presence and effectiveness of catalytic
    converters), and what is the relationship between cabin
    concentrations and health effects on cabin occupants?

-   Cabin pressure and oxygen partial pressure. What is the effect of
    cabin pressure altitude on susceptible cabin occupants, including
    infants, pregnant women and people with cardiovascular disease?

-   Outside-air ventilation. Does the ECS provide sufficient quantity
    and distribution of outside air to meet the FAA regulatory
    requirements (FAR 25.831), and to what extent is cabin ventilation
    associated with complaints form passengers and cabin crew? Can it be
    verified that infectious-disease agents are transmitted primarily
    between people in close proximity? Does recirculation of cabin air
    increase cabin occupants' risk of exposure?

-   Air quality incidents. What is the toxicity of the constituents or
    degradation products of engine lubricating oils, hydraulic fluids,
    and deicing fluids, and is there a relationship between exposures to
    them and reported health effects on cabin crew? How are these oils,
    fluids, and degradation products distributed from the engines into
    the ECS and throughout the cabin environment?

-   Pesticide exposure. What are the magnitudes of exposures to
    pesticides in aircraft cabins and what is the relationship between
    the exposures and reported symptoms?

-   Relative humidity. What is the contribution of low relative humidity
    to the perception of dryness, and do other factors cause or
    contribute to the irritation associated with the dry cabin
    environment during flight?

**Table S-2, Surveillance and Research Programs**

[Research Program Objectives]{.underline}

-   To investigate possible association between specific air quality
    characteristics and health effects or complaints

-   To evaluate the physical and chemical factors affecting specific air
    quality characteristics in aircraft cabins

-   To determine whether FAR's for air quality are adequate to protect
    health and ensure comfort of passengers and crew

-   To determine exposure to selected contaminants (e.g., constituents
    of engine lubricating oils and hydraulic fluids, their degradation
    products, and pesticides) and establish their potential toxicity
    more fully

[Research Program Approach]{.underline}

-   Use continuous monitoring data from surveillance program when
    possible

-   Monitor additional air quality characteristics on selected flights
    as necessary (e.g., integrated particulate-matter sampling to assess
    exposure to selected contaminants)

-   Identify and monitor "problem" aircraft and review maintenance and
    repair record to evaluate issues associated with air quality
    incidents

-   Collect selected health data (e.g., pulse-oximetry data to assess
    arterial O~2~ saturation of passengers and crew)

-   Conduct laboratory and other ground-based studies to characterize
    air distribution and circulation and contaminant generation,
    transport, and degradation in the cabin and ECS

**Response**

NRC's report noted that existing air quality data are inadequate for
evaluating the possible association between air contaminants and cabin
environmental conditions during routine operations and the health
problems and complaints from passengers or crewmembers. Data are also
inadequate regarding the possible associations of cabin air quality and
health effects for non-routine operations. As discussed in previous
sections, data on accident and incident, pilot incapacitation, and
Medair calls are available but reports seldom contain actual air sample
contaminant data. To address these issues, NRC's report proposed a
combined surveillance and multifaceted research program addressing
"Air-quality Surveillance, Health Surveillance, Air Quality Research,
and Staging." FAA concurs with the intent of this recommendation.

The NRC report is a well-documented assessment of the questions
currently facing FAA and the aviation industry concerning transport
aircraft air quality and health and comfort issues. While the report
does not identify significant flight safety issues related to the cabin
environment, these too deserve future research attention. To address
these issues, the simplest step facing the researcher may be to develop
sampling equipment and techniques to determine air quality. The most
difficult step may be to accurately relate the cabin air quality to a
given effect and to determine if the effect is health or simply comfort
related. A combined effort by aviation officials (government, union, and
industry) will be needed to develop and execute a successful research
effort.

**Discussion**

[Air Quality Surveillance.]{.underline} As mentioned in the discussion
of Recommendation 8, FAA has initiated a cabin air quality monitoring
effort through NIOSH. While this project has not included monitoring (33
flights during the last 2 years), sampling capability and procedures
have been developed, and further monitoring will be conducted. NRC's
report suggested that an air quality surveillance program should conduct
air sampling on a minimum of 100 flights. A modification and
continuation of the NIOSH effort could meet this recommendation and
provide initial air quality and health effects data to determine if more
extensive efforts are required for routine flight conditions.

### 

[Health Surveillance.]{.underline} The NIOSH effort did conduct a health
effects survey. This survey included a questionnaire for flight
attendants and a comparison group of schoolteachers. The NIOSH study was
partially successful in gathering questionnaire data. Currently the
NIOSH study is attempting to validate the questionnaire data through a
follow-up review of actual medical data. NRC's report notes that to
provide an effective cabin air quality assessment, both air samples and
occupant health questionnaire data should be gathered from the same
flight. The report also notes that the principal focus of the health
questionnaire should be the flight attendants. While it is recognized
that air quality in the cabin section of the aircraft could be different
from the cockpit, the pilots are required to undergo frequent medical
examinations and have significant medical documentation that could be
used to establish preexisting conditions and validate questionnaire
responses. Such information might not be available from the flight
attendants and the researcher is faced with subjective health
questionnaire data that may or may not be supported by medical
information.

FAA gathers data from any reported pilot incapacitation and has data on
failures of cabin pressure, smoke, or fumes in the aircraft or other
major environmental control system failures. Additionally, FAA gathers
information from in-flight or flight-related medical events that are
reported through Medaire. While these reports are generally focused on
flight safety issues, reports on any use of the in-flight emergency
medical kit and the equipment/medications used are provided. The
presence or absence of reported medical incidents might assist in
developing a monitoring program to evaluate major health-related issues.
FAA conducted an evaluation on the use of the Automated External
Defibrillators (AEDs) carried onboard commercial aircraft in 1996-97.
This evaluation provided in-flight medical information, but when the
passenger was removed from the aircraft to a medical facility, tracking
and gathering medical data became very difficult. Similar follow-up
problems may be inherent in any in-flight health reporting system or
assessment.

### 

[Air Quality Research.]{.underline} NRC's report identifies air quality
research as separate from the surveillance programs but closely related.
Areas specifically identified for more intensive research were ozone,
cabin pressure and oxygen partial pressure, and outside air ventilation.

[Ozone.]{.underline} From the data available, NRC's report concludes
that CO and CO~2~ concentrations generally do not appear to exceed FAA
guidelines, although they may on occasion. Other sections of the report
note that symptoms of ozone exposure are nonspecific and that common
respiratory symptoms could be rightly or wrongly attributed to ozone
exposure. In this proposed research area, the major emphasis appears to
be the definition of ozone concentrations in various phases of flight,
the interaction/reaction of ozone with cabin surfaces and the
effectiveness of ozone converters in the aircraft. As discussed under
the response to Recommendation 8, a preliminary sampling of a number of
aircraft could help define the ozone concentration levels and, if
aircraft with and without ozone converters are sampled, a preliminary
finding on the effectiveness of ozone converters could be developed.

[Cabin Pressure and Oxygen Partial Pressure.]{.underline} NRC's report
suggested that cabin pressure equivalents of 8,000 feet could be
hazardous for susceptible passengers, such as those with pulmonary or
cardiovascular disease and infants). Headache and other symptoms of mild
altitude sickness may occur in some healthy individuals at elevations
below 8,000 feet, a phenomenon encountered not infrequently by
physicians practicing in mountainous areas. NRC's report suggested that
pulse oximetry techniques could be used in-flight to monitor hemoglobin
saturation in the passengers and crew.

NRC documented a significant literature in this area. However, the
majority of the research has been conducted on healthy individuals in
appropriate research facilities. An evaluation of the effect of altitude
on susceptible individuals would require significant medical evaluation
to determine the extent of their disability and to relate this
disability to arterial oxygen levels. These procedures would not be
possible in a flight environment. An in-depth review of current medical
research should be conducted to determine if adequate information is
available to better advise physicians and the flying public on medical
fitness to fly questions. As emphasized in Recommendation 6, education
of health professionals, aircrew, and the flying population is an
important flight safety concern.

[Outside Air Ventilation.]{.underline} Comments on Recommendation 1
address FAA certification requirements for airflow in the passenger
compartment of a transport aircraft. The adequacy of these requirements
and general questions regarding bioaerosol transmission in the aircraft
are being studied at several levels. The NIOSH cabin environment
research effort includes a study of in-flight disease transmission. An
environmental chamber and a Computational Fluid Dynamics (CFD) model
were developed to measure and track particles emitted during
physiological maneuvers (speaking, coughing, and sneezing).
Additionally, the NIOSH study contracted with a major aircraft
manufacturer to develop a model of airflow within a transport aircraft
cabin to determine airflow pattern of bioaerosols. In a separate effort,
CAMI started development of a CFD model to evaluate the potential spread
of biological or chemical weapons materials in an aircraft. This study
is using airflow data gathered from their Boeing 747 cabin environment
simulator to support the modeling effort.

### 

[Air Quality Incidents.]{.underline} In Chapter 8 of its report, NRC
noted that gathering cabin air quality and health effects data during
infrequently occurring air quality incidents is a difficult issue. The
report correctly observes that air handling system failures are an
infrequent event and accurate sampling of induced contaminants would
require monitoring thousands of flights. The report suggests that the
task of gathering samples during air quality incidents could be made
less daunting by using aircraft maintenance data to focus on specific
aircraft or aircraft types. Obviously such use of aircraft maintenance
information would support a monitoring effort; however, industry legal
and operational concerns could affect the effort. FAA and industry
knowledge of the frequency of air quality incidents would be improved by
requiring crewmembers to report all such events. The issue of air
quality incidents will be included in FAA rulemaking activities.

# NRC Recommendation 10 -- Research Program Lead Agency 

*The committee recommends that Congress designate a lead federal agency
and provide sufficient funds to conduct or direct the research program
proposed in recommendation 9, which is aimed at filling major knowledge
gaps identified in this report. An independent advisory committee with
appropriate scientific, medical, and engineering expertise should be
formed to oversee the research program to ensure that its objectives are
met and the results publically disseminated.*

**Response**

NRC recommended the Congressional designation and funding of a research
program with an independent advisory committee. FAA concurs with the
recommendation and recommends that FAA be designated as the lead federal
agency for the air quality research program and that sufficient
additional funding be appropriated to accomplish NRC's recommended
environmental monitoring, data collection, and research initiatives. FAA
also proposes to include the research needs related to biological and
chemical terrorism on board aircraft with those related to air quality.
To this end, the FAA Administrator will recommend to the Secretary of
Transportation that a cooperative effort with the Transportation
Security Administration (TSA) be initiated to place sensor devices on U.
S. air carrier aircraft. The devices would monitor airliner cabin air
quality and detect biological and chemical contamination of cabin air in
a manner that warns the aircrew and locates the source of contamination.

**Discussion**

The cooperative effort described above will address the air quality
concerns of the flying public as well as the concerns of crewmembers and
will provide a preemptive level of security against biological and
biochemical attack recommended by national scientific experts
knowledgeable in this area. Through this approach, the Administrator
will implement NRC's recommendations relative to environmental
monitoring and data collection and further address with TSA security
concerns of the aviation industry and the flying public.

The expanded nature of the response will require additional resources
beyond those necessary to meet the basic NRC recommendations. The
Administrator will request Congress to provide additional funding to
support these FAA initiatives. The request will include funds to support
research for the cabin air monitoring and data collection as well as the
research initiatives recommended by NRC.

The Administrator will implement the cabin air monitoring, data
collection and other research initiatives through collaboration with
research and standardization organizations.

#  

# Appendix 1 -- Regulations and Related Material Cited in the Report

## 14CFR Part 25, §25.831 - Ventilation

> (a)Under normal operating conditions and in the event of any probable
> failure conditions of any system which would adversely affect the
> ventilating air, the ventilation system must be designed to provide a
> sufficient amount of uncontaminated air to enable the crewmembers to
> perform their duties without undue discomfort or fatigue and to
> provide reasonable passenger comfort. For normal operating conditions,
> the ventilation system must be designed to provide each occupant with
> an airflow containing at least 0.55 pounds of fresh air per minute.
>
> \(b\) Crew and passenger compartment air must be free from harmful or
> hazardous concentrations of gases or vapors. In meeting this
> requirement, the following apply:
>
> \(1\) Carbon monoxide concentrations in excess of 1 part in 20,000
> parts of air are considered hazardous. For test purposes, any
> acceptable carbon monoxide detection method may be used.
>
> \(2\) Carbon dioxide concentration during flight must be shown not to
> exceed 0.5 percent by volume (sea level equivalent) in compartments
> normally occupied by passengers or crewmembers.
>
> \(c\) There must be provisions made to ensure that the conditions
> prescribed in paragraph (b) of this section are met after reasonably
> probable failures or malfunctioning of the ventilating, heating,
> pressurization, or other systems and equipment.
>
> \(d\) If accumulation of hazardous quantities of smoke in the cockpit
> area is reasonably probable, smoke evacuation must be readily
> accomplished, starting with full pressurization and without
> depressurizing beyond safe limits.
>
> \(e\) Except as provided in paragraph (f) of this section, means must
> be provided to enable the occupants of the following compartments and
> areas to control the temperature and quantity of ventilating air
> supplied to their compartment or area independently of the temperature
> and quantity of air supplied to other compartments and areas:
>
> \(1\) The flight crew compartment.
>
> \(2\) Crewmember compartments and areas other than the flight crew
> compartment unless the crewmember compartment or area is ventilated by
> air interchange with other compartments or areas under all operating
> conditions.
>
> \(f\) Means to enable the flight crew to control the temperature and
> quantity of ventilating air supplied to the flight crew compartment
> independently of the temperature and quantity of ventilating air
> supplied to other compartments are not required if all of the
> following conditions are met:
>
> \(1\) The total volume of the flight crew and passenger compartments
> is 800 cubic feet or less.
>
> \(2\) The air inlets and passages for air to flow between flight crew
> and passenger compartments are arranged to provide compartment
> temperatures within 5 degrees F. of each other and adequate
> ventilation to occupants in both compartments.
>
> \(3\) The temperature and ventilation controls are accessible to the
> flight crew.
>
> \(g\) The exposure time at any given temperature must not exceed the
> values shown in the following graph after any improbable failure
> condition.
>
> Temperature curve from Amdt. 25-87

![](media/image6.png){width="6.498611111111111in"
height="2.928472222222222in"}

> \[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt.
> 25-41, 42 FR 36970, Jul. 18, 1977; Amdt. 25-87, 61 FR 28695, Jun. 5,
> 1996; Amdt. 25-89, 61 FR 63956, Dec. 2, 1996\]

## 14CFR Part 25, §25.832 - Cabin Ozone Concentration

> \(a\) The airplane cabin ozone concentration during flight must be
> shown not to exceed-
>
> \(1\) 0.25 parts per million by volume, sea level equivalent, at any
> time above flight level 320; and
>
> \(2\) 0.10 parts per million by volume, sea level equivalent,
> time-weighted average during any 3-hour interval above flight level
> 270.
>
> \(b\) For the purpose of this section, \'\'sea level equivalent\'\'
> refers to conditions of 25o C and 760 millimeters of mercury pressure.
>
> \(c\) Compliance with this section must be shown by analysis or tests
> based on airplane operational procedures and performance limitations,
> that demonstrate that either-
>
> \(1\) The airplane cannot be operated at an altitude which would
> result in cabin ozone concentrations exceeding the limits prescribed
> by paragraph (a) of this section; or
>
> \(2\) The airplane ventilation system, including any ozone control
> equipment, will maintain cabin ozone concentrations at or below the
> limits prescribed by paragraph (a) of this section.
>
> \[Amdt. 25-50, 45 FR 3883, Jan. 1, 1980, as amended by Amdt. 25-56, 47
> FR 58489, Dec. 30, 1982\]

## 14CFR Part 121, §121.578 - Cabin Ozone Concentration

\(a\) For the purpose of this section, the following definitions apply:

> \(1\) \"Flight segment\" means scheduled nonstop flight time between
> two airports.
>
> \(2\) \"Sea level equivalent\" refers to conditions of 25^o^C and 760
> millimeters of mercury pressure.
>
> \(b\) Except as provided in paragraphs (d) and (e) of this section, no
> certificate holder may operate an airplane above the following flight
> levels unless it is successfully demonstrated to the Administrator
> that the concentration of ozone inside the cabin will not exceed:
>
> \(1\) For flight above flight level 320, 0.25 parts per million by
> volume, sea level equivalent, at any time above that flight level; and
>
> \(2\) For flight above flight level 270, 0.1 parts per million by
> volume, sea level equivalent, time-weighted average for each flight
> segment that exceeds 4 hours and includes flight above that flight
> level (For this purpose, the amount of ozone below flight level 180 is
> considered to be zero).
>
> \(c\) Compliance with this section must be shown by analysis or tests,
> based on either airplane operational procedures and performance
> limitations or the certificate holder\'s operations. The analysis or
> tests must show either of the following:
>
> \(1\) Atmospheric ozone statistics indicate, with a statistical
> confidence of at least 84%, that at the altitudes and locations at
> which the airplane will be operated cabin ozone concentrations will
> not exceed the limits prescribed by paragraph (b) of this section.
>
> \(2\) The airplane ventilation system including any ozone control
> equipment, will maintain cabin ozone concentrations at or below the
> limits prescribed by paragraph (b) of this
>
> section.
>
> \(d\) A certificate holder may obtain an authorization to deviate from
> the requirements of paragraph (b) of this section, by an amendment to
> its operations specifications, if:
>
> \(1\) It shows that due to circumstances beyond its control or to
> unreasonable economic burden it cannot comply for a specified period
> of time; and
>
> \(2\) It has submitted a plan acceptable to the Administrator to
> effect compliance to the extent possible.
>
> \(e\) A certificate holder need not comply with the requirements of
> paragraph (b) of this section for an aircraft:
>
> \(1\) When the only persons carried are flight crewmembers and persons
> listed in Sec. 121.583;
>
> \(2\) If the aircraft is scheduled for retirement before January 1,
> 1985; or
>
> \(3\) If the aircraft is scheduled for re-engining under the
> provisions of Subpart E of Part 91, until it is re-engined.
>
> \[Doc. No. 121-154, 45 FR 3883, Jan. 21, 1980. Redesignated by Amdt.
> 121-162, 45 FR 46739, July 10, 1980; Amdt. 121-181, 47 FR 58489, Dec.
> 30, 1982; Amdt. 121-251, 60 FR 65935, Dec. 20, 1995\]

## 14CFR Part 25, §25.841 - Pressurized Cabins

> \(a\) Pressurized cabins and compartments to be occupied must be
> equipped to provide a cabin pressure altitude of not more than 8,000
> feet at the maximum operating altitude of the airplane under normal
> operating conditions.
>
> \(1\) If certification for operation above 25,000 feet is requested,
> the airplane must be designed so that occupants will not be exposed to
> cabin pressure altitudes in excess of 15,000 feet after any probable
> failure condition in the pressurization system.
>
> \(2\) The airplane must be designed so that occupants will not be
> exposed to a cabin pressure altitude that exceeds the following after
> decompression from any failure condition not shown to be extremely
> improbable:
>
> \(i\) Twenty-five thousand (25,000) feet for more than 2 minutes; or
>
> \(ii\) Forty thousand (40,000) feet for any duration.
>
> \(3\) Fuselage structure, engine and system failures are to be
> considered in evaluating the cabin decompression.
>
> \(b\) Pressurized cabins must have at least the following valves,
> controls, and indicators for controlling cabin pressure:
>
> \(1\) Two pressure relief valves to automatically limit the positive
> pressure differential to a predetermined value at the maximum rate of
> flow delivered by the pressure source. The combined capacity of the
> relief valves must be large enough so that the failure of any one
> valve would not cause an appreciable rise in the pressure
> differential. The pressure differential is positive when the internal
> pressure is greater than the external.
>
> \(2\) Two reverse pressure differential relief valves (or their
> equivalents) to automatically prevent a negative pressure differential
> that would damage the structure. One valve is enough, however, if it
> is of a design that reasonably precludes its malfunctioning.
>
> \(3\) A means by which the pressure differential can be rapidly
> equalized.
>
> \(4\) An automatic or manual regulator for controlling the intake or
> exhaust airflow, or both, for maintaining the required internal
> pressures and airflow rates.
>
> \(5\) Instruments at the pilot or flight engineer station to show the
> pressure differential, the cabin pressure altitude, and the rate of
> change of the cabin pressure altitude.
>
> \(6\) Warning indication at the pilot or flight engineer station to
> indicate when the safe or preset pressure differential and cabin
> pressure altitude limits are exceeded. Appropriate warning markings on
> the cabin pressure differential indicator meet the warning requirement
> for pressure differential limits and an aural or visual signal (in
> addition to cabin altitude indicating means) meets the warning
> requirement for cabin pressure altitude limits if it warns the flight
> crew when the cabin pressure altitude exceeds 10,000 feet.
>
> \(7\) A warning placard at the pilot or flight engineer station if the
> structure is not designed for pressure differentials up to the maximum
> relief valve setting in combination with landing loads.
>
> \(8\) The pressure sensors necessary to meet the requirements of
> paragraphs (b)(5) and (b)(6) of this section and 25.1447(c), must be
> located and the sensing system designed so that, in the event of loss
> of cabin pressure in any passenger or crew compartment (including
> upper and lower lobe galleys), the warning and automatic presentation
> devices, required by those provisions, will be actuated without any
> delay that would significantly increase the hazards resulting from
> decompression.
>
> \[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt.
> 25-38, 41 FR 55466, Dec. 20, 1976; Amdt. 25-87, 61 FR 28696, Jun. 5,
> 1996\]

## 14CFR Part 21, §121.805 - Crewmember Training for In-flight Medical Events

> \(a\) Each training program must provide the instruction set forth in
> this section\
> with respect to each airplane type, model, and configuration, each
> required\
> crewmember, and each kind of operation conducted, insofar as
> appropriate for\
> each crewmember and the certificate holder.\
> (b) Training must provide the following:\
> (1) Instruction in emergency medical event procedures, including
> coordination\
> among crewmembers.\
> (2) Instruction in the location, function, and intended operation of
> emergency\
> medical equipment.\
> (3) Instruction to familiarize crewmembers with the content of the
> emergency\
> medical kit.\
> (4) Instruction to familiarize crewmembers with the content of the
> emergency\
> medical kit as modified on April 12, 2004.\
> (5) For each flight attendant \--\
> (i) Instruction, to include performance drills, in the proper use of
> automated\
> external defibrillators.\
> (ii) Instruction, to include performance drills, in cardiopulmonary\
> resuscitation.\
> (iii) Recurrent training, to include performance drills, in the proper
> use of an\
> automated external defibrillator and in cardiopulmonary resuscitation
> at least\
> once every 24 months.\
> (c) The crewmember instruction, performance drills, and recurrent
> training\
> required under this section are not required to be equivalent to the
> expert\
> level of proficiency attained by professional emergency medical
> personnel.

## The Air Carrier Access Act (ACAA) Rules 

> Carriers shall permit dogs and other service animals used by
> individuals with disabilities to accompany the person on a flight.
>
> \(1\) Carriers shall accept as evidence that an animal is a service
> animal identification cards, other written documentation, presence of
> harnesses or markings on harnesses, tags or the credible verbal
> assurances of the qualified individual with disabilities using the
> animal.
>
> \(2\) Carriers shall permit a service animal to accompany a qualified
> individual with disabilities in any seat in which the person sits,
> unless the animal obstructs an aisle or other area that must remain
> unobstructed in order to facilitate an emergency evacuation.

##   FAA Advisory Circular 120-44A

> The Handling of Illness and Injury. An air carrier\'s first aid
> program should provide information about protection of crewmembers
> from bloodborne pathogens (including use of barrier gloves),
> familiarization with the contents of the medical kit and the
> assessment of the severity and possible treatment of the medical
> problems listed below. This list also provides suggestions pertinent
> to some problems. However, neither the list nor the suggestions are
> all inclusive. Each air carrier should develop first aid programs that
> are appropriate to that air carrier\'s operations, equipment, and
> personnel. These programs should include information on the
> following:\
> \
> (1) History and Assessment of individuals who are ill or injured. This
> information should be communicated to the flight crewmembers, any
> on-board medical assistants, and anyone offering medical assistance to
> the flight from the ground, and should be given to medical personnel
> who meet the flight....\
> (4) Shock, Unconsciousness, Major Allergic Response....\
> d. Assistance.\
> (1) From Persons on Board. Each first aid program should provide a
> procedure for identifying medically qualified persons on board the
> aircraft. These procedures should list those persons who would be
> considered medically qualified. For example, medical doctors, nurses,
> emergency medical technicians, or first aid instructors could be
> listed.\
> (2) From Persons on the Ground. Many airlines have procedures which
> allow crewmembers on board the flight to consult with medical
> personnel on the ground. This practice is highly desirable. Air
> carrier manuals and training should provide guidelines to crewmembers
> about obtaining medical consultation from the ground. The information
> obtained through the medical history and assessment should be passed
> on to these medical personnel.

# Appendix 2 -- Abbreviations and Acronyms Used in the Report

ACAA: Air Carrier Access Act

AED: Automated External Defibrillators

AFSA Association of Flight Attendants

AIDS: Accidents and Incident Data Systems

AME: Aviation Medical Examiner

ASHRAE: American Society of Heating, Refrigerating and Air-conditioning
Engineers, Inc.

ASRS: Aviation Safety Research System

ARAC: Aviation Rulemaking Advisory Committee

CAMI: Civil Aerospace Medical Institute

C/B: Chemical and biological

CFD: Computational Fluid Dynamics

cfm cubic feet per minute

CFR: Code of Federal Regulations

CO: Carbon Monoxide

CO~2~: Carbon Dioxide

DOD Department of Defense

DOT: Department of Transportation

ECS: Environmental Control System

FAA: Federal Aviation Administration

FAR: Federal Aviation Regulation

HEPA: High Efficiency Particulate Air

lbm pounds mass

Medaire: A worldwide aviation medical support system

NAS: National Academy of Sciences

NASA: National Aeronautics and Space Administration

NASDAC: National Aviation Safety Data Analysis Center

NIOSH: National Institute for Occupational Safety and Health

NO~2:~ Nitrogen Dioxide

NRC: National Research Council

NTSB: National Transportation Safety Board

O~3~: Ozone

OSHA: Occupational Safety and Health Awareness

PM: Particulate material

RE and D Research, Engineering and Development

REL Recommended Exposure Limit

RSP: Respirable Suspended Particulate

SDRS: Service Difficulty Reporting System

TSA Transportation Security Administration

VOC: Volatile Organic Compound

[^1]: See Appendix 1 for full text of all CFRs cited

[^2]: Advisory Circular AC 120-38, Transport Category Airplanes Cabin
    Ozone Concentrations

[^3]: NASA Earth Observing System (EOS) Handbook available at
    http://eospso.gsfc.nasa.gov/

[^4]: For example, Table 1, "Major and Selected Trace Gases in the
    Atmosphere", "Global Biomass Burning: Atmospheric, Climatic, and
    Biospheric Implications, Levine, J.S., ed, published by MIT press,
    Inc, 1991,

[^5]: See Appendix for partial text

[^6]: See Appendix 1, §121.805 -- Crewmember Training for In-flight
    Medical Events

[^7]: "Occurrence of Dog, Cat and Mite Allergens in Public Transport
    Vehicles"; Partti-Pellinen K., Marttila O., Makinen-Kiljunen S.,
    Haahtela T. [Allergy]{.underline} 55(1): 65-8, 2000.

[^8]: Reported in DOT/FAA/AM-97/2 DeJohn, Véronneau, Hordinsky and
    DOT/FAA/AM-00/13 DeJohn, Véronneau, Wolbrink, Larcher

[^9]: [Obstet. Gynecol]{.underline}. 2001; 98:1187-1188

[^10]: PL 103-305, §304