[Federal Register Volume 61, Number 232 (Monday, December 2, 1996)]
[Rules and Regulations]
[Pages 63952-63956]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-30525]
[[Page 63951]]
_______________________________________________________________________
Part IV
Department of Transportation
_______________________________________________________________________
Federal Aviation Administration
Allowable Carbon Dioxide Concentration in Transport Category Airplane
Cabins; Final Rule
Federal Register / Vol. 61, No. 232 / Monday, December 2, 1996 /
Rules and Regulations
[[Page 63952]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. 27704, Amdt. No. 25-89]
RIN 2120-AD47
Allowable Carbon Dioxide Concentration in Transport Category
Airplane Cabins
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: This amendment revises the standards for maximum allowable
carbon dioxide (CO2) concentration in occupied areas of transport
category airplanes by reducing the maximum allowable concentration from
3 percent to 0.5 percent. This action is in response to a
recommendation from the National Academy of Sciences to review the
CO2 limit in airplane cabins, and provides a cabin CO2
concentration level representative of that recommended by some
authorities for buildings.
EFFECTIVE DATE: January 2, 1997.
FOR FURTHER INFORMATION CONTACT: Kristin L. Larson, FAA, Flight Test
and Systems Branch, ANM-111, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-
4056; telephone (206) 227-1760, facsimile (206) 227-1100.
SUPPLEMENTARY INFORMATION:
Background
This amendment is based on Notice of Proposed Rulemaking No. 94-14,
published in the Federal Register on May 2, 1994 (59 FR 22718). As
discussed in that notice, this action reduces the maximum allowable
carbon dioxide concentration level from 3 percent to 0.5 percent.
In October 1984, the Department of Transportation was directed by
Congress (Public Law 98-466) to commission the National Academy of
Sciences (NAS) to conduct an independent study on the cabin air quality
in transport category airplanes. The NAS formed the Committee on
Airliner Cabin Air Quality to study all safety aspects of airliner
cabin air quality, and submitted its report, ``The Airliner Cabin
Environment--Air Quality And Safety,'' to the FAA on August 12, 1986.
One of the recommendations in the report relates to the allowable
carbon dioxide (CO2) concentration in the airplane cabin. This
action is a result of that recommendation. For the purposes of this
rule, the term ``cabin'' is meant to include the passenger cabin, the
flight deck, lower lobe galleys, crew rest areas, and any other areas
occupied by passengers or crew members in a transport category
airplane.
Discussion
Carbon dioxide is the product of normal human metabolism, which is
the predominant source in airplane cabins. The CO2 concentration
in the cabin depends on the ventilation rate, the number of people
present, and their individual rates of CO2 production, which
varies with activity and (to a smaller degree) with diet and health.
Carbon dioxide is also generated by sublimation of dry ice used to cool
food in the galleys, and to preserve certain cargo carried in the cargo
compartments. The carbon dioxide concentration level is frequently used
as an indication of general air quality. At concentrations above a
given level, complaints of poor air quality or ``stuffiness'' begin to
appear.
The maximum CO2 limit of Sec. 25.831(b)(2) of the Federal
Aviation Regulations (FAR) is 3 percent by volume, sea level
equivalent. This 3 percent limit was incorporated into Sec. 4b.371 of
the Civil Air Regulations (CAR) by Amendment 4b6 on March 5, 1952. This
limit was carried over into 14 CFR part 25 when this part was codified
in 1965. This high limit was established to allow for increases in the
carbon dioxide levels in the crew compartment to ensure that, in
airplanes with built-in carbon dioxide fire extinguishing systems, safe
carbon dioxide concentration levels would not be exceeded in the
occupied areas when combating fires in cargo compartments.
The American Conference of Governmental Industrial Hygienists
(ACGIH) has adopted a short-term exposure limit (STEL) for CO2 of
30,000 parts per million (3 percent). The 3 percent limit specified in
part 25 may therefore be satisfactory as a short-term limit, but is
inappropriate for a steady-state condition. However, the NAS Committee
notes in their report that this 3 percent limit is much higher than the
limits adopted by the air conditioning industry for buildings and other
types of interior environments, and recommends that the limit specified
in part 25 be revised to more closely match the currently acceptable
limits. The FAA concurs.
In contrast to the 3 percent limit specified in part 25, the
American Society of Heating, Refrigerating, and Air-Conditioning
Engineers (ASHRAE), in their Standard 62-1989, recommends an outside
air ventilation rate of 15 cubic feet per minute for vehicles. Based on
the ASHRAE calculations, this equates to a CO2 limit of 1,000
parts per million (PPM), or 0.1 percent, if the occupants have a low
physical activity level. As most of the airplane occupants are
passengers who are not active, this is a reasonable parallel. ASHRAE
standards such as the 0.1 percent CO2 limit are frequently quoted
in magazine and newspaper articles when reporting on airliner cabin air
quality.
As CO2 concentration in the air increases, there is an
increase in both the rate and the depth of breathing, reaching twice
the normal rate at 3 percent concentration. At 3 percent concentration,
there is some discomfort; at higher concentrations, headache, malaise,
and, occasionally, fatigue occur, and the air is reported by those
affected as being stale. People can function for long periods of time
at levels of CO2 as high as 1 percent (as in nuclear submarines),
but it is generally felt by ASHRAE that 0.1 percent is a better limit.
This value, however, is based on the dissipation of smoke and odors and
not on health considerations. As noted above, according to ASHRAE
Standard 62-1989, a steady-state CO2 concentration of 0.1 percent
would require a fresh-air ventilation rate of 15 cubic feet per minute
(cfm) per person. In the previous edition of the standard (62-1981),
ASHRAE recommended a limit of 0.5 percent for office buildings and
other occupied spaces, but suggested that 0.25 percent would provide an
additional safety factor. The ASHRAE standard is intended to be used as
a comfort standard rather than a health and safety standard. ASHRAE has
recognized that the 0.1 percent CO2 concentration limit may not be
appropriate for airliner cabins, and has formed an aviation
subcommittee, the charter of which is to develop a transport airplane
cabin air quality standard. While this subcommittee is not an FAA
advisory committee, industry often uses ASHRAE standards in designing
systems. The subcommittee will sponsor research studies to determine
the quality of the ambient air and quantify the correlation between
measurable contaminants and passenger perception of air quality. As
noted above, ASHRAE standards were intended to be used for buildings
rather than vehicles such as airplanes, and they consider it
appropriate to establish a new standard for airplanes at this time.
The Occupational Safety and Health Administration (OSHA), in
Sec. 1910.1000 of part 1910 (CFR 29), sets an interim (transitional)
limit for CO2 at 5,000 ppm or 0.5 percent, with a final rule limit
of
[[Page 63953]]
10,000 ppm or 1 percent, effective December 31, 1993. The increase to 1
percent is apparently in deference to operators of commercial bakeries
and breweries, both of which generate a significant amount of CO2
in their processes. The FAA does not believe it is appropriate to base
the allowable CO2 concentration in transport category airplanes on
the needs of specific manufacturing processes. Other commercial
enterprises have no difficulty in meeting the existing OSHA limit of
0.5 percent.
The American Conference of Governmental Industrial Hygienists, in
its ``Documentation of the Threshold Limit Values and Biological
Exposure Indices--Sixth Edition,'' also recommends 0.5 percent as a
limit, but ACGIH recommends this value as a time-weighted average limit
for repeated daily exposure by workers. The FAA is adopting this value
as a limit. A concentration limit of 0.5 percent is considered to be
appropriate because there are no documented safety or health benefits
associated with the establishment of a lower value.
Copies of the pertinent documents from ASHRAE, OSHA, and ACGIH have
been placed in the public docket for this rulemaking.
Cabin ventilation provides air for dilution of airborne
contaminants, and supplies oxygen for passengers and crew. Oxygen
requirements for sedentary adults can be met with a fresh-air
ventilation rate of only 0.24 cubic feet per minute (CFM) per person.
Ventilation rates for current transport category airplanes vary from a
low of approximately 7 cfm per person (with one or more air
conditioning packs turned off for economy), to over 20 cfm per person
(which includes up to 50 percent filtered, recirculated air). Thus,
even at the lowest ventilation rates available on current airplanes,
there is no significant reduction in the percentage of oxygen, or
increase in the amount of water vapor in the cabin due to respiration.
However, the design parameters for the ventilation systems are driven
by operation on the ground during hot days. Contamination of air with
CO2 varies inversely with the ventilation rate, because CO2
production by sedentary people is nearly constant.
In order to bring the maximum allowable carbon dioxide
concentration into concert with accepted modern limits, this rule
adopts a new maximum allowable carbon dioxide concentration of 0.5
percent. According to ASHRAE, for sedentary people this concentration
can be maintained by a fresh air flow rate of 2.25 cfm per person,
which is lower than that currently measured in transport category
airplanes.
Section 25.831(b)(2) currently reads, ``Carbon dioxide in excess of
three percent . . . is considered hazardous in the case of
crewmembers.'' The health and comfort considerations discussed earlier
are equally valid for passengers. Therefore, the FAA has removed the
reference to crewmembers. In addition, Sec. 25.831(b)(2) also specifies
that, ``Higher concentrations of carbon dioxide may be allowed in crew
compartments if appropriate protective breathing equipment is
available.'' This sentence was incorporated when the 3 percent limit
was established in CAR 4b.371 in 1952. As noted above, the origins of
the 3 percent limit are unclear, but it is likely that the limit was
set at this high level to account for the discharge of CO2 fire
extinguishers in the flight deck, cabin, or cargo compartment. This
thesis is supported by the mention of protective breathing in the
existing rule. However, most CO2 extinguishers have been replaced
by Halon or other types of fire extinguishers. Further, the rule is not
intended to cover the short-duration rise in CO2 concentration
that would accompany discharge of a fire extinguisher. Therefore, that
sentence in Sec. 25.831(b)(2) is removed because it is no longer
considered necessary or appropriate.
Section 25.831(b)(1) specifies a limit for carbon monoxide (CO)
concentration of 1 part in 20,000 parts air (0.005 percent). This limit
is the same as currently recommended by ASHRAE and the Occupational
Safety and Health Administration (OSHA), and therefore this action does
not change this limit.
Discussion of Comments
Comments were received from foreign and domestic airplane
manufacturers through their respective trade associations, foreign
airworthiness authorities, trade organizations representing flight
attendants and US and Canadian pilots, one US operator, an organization
representing airline passengers, and several individuals.
Two commenters support the proposed change as it appears in the
notice. Five commenters wrote to register dissatisfaction with the air
quality on airplanes, mentioning both comfort for passengers and
illnesses believed to be associated with inadequate fresh air flow. One
commenter urges the FAA to ``make the changes necessary so that we can
fly in reasonable health.'' Another commenter is of the opinion that
``very poor recirculation of air in planes is costing a lot of money in
medical terms, not to mention suffering.'' Two commenters state that
the FAA should perform tests on existing airplanes. The FAA infers from
these comments that the commenters are in favor of revising the
requirements to ensure acceptable air quality. Studies conducted by the
FAA and others do not indicate that there is a health hazard associated
with cabin air quality. As none of these commenters suggest specific
changes to the proposal, there are no changes to the final rule in
response to the comments.
One commenter misread the proposal as to the allowable
concentration currently in the regulations and that proposed in the
notice. This commenter states that the standards for cabin air quality
should be better than the standard set for buildings, because the
population density is higher in an airplane, and in an office building
people may exit periodically. While the commenter made no specific
recommendations, the FAA infers that the commenter advocates lower
limits than proposed in the notice. The FAA does not concur that these
factors justify a requirement for a lower carbon dioxide concentration.
The existing standards are all based on a ventilation rate per
occupant. To meet the same requirements with a higher population
density, a greater volume of fresh air ventilation is required. It is
not clear how this concern can be addressed by the airline industry or
the FAA when the studies conducted indicate that the air quality in
airplanes does not present a hazard to the health of the travelers.
Two commenters state that the proposed 0.5 percent carbon dioxide
concentration limit is too high. One commenter suggests that the FAA
``set a limit of 800 parts per million (ppm), the same level proposed
by the Occupational Safety and Health Administration for indoor air
quality,'' which is 0.08 percent. Another commenter recommends that the
FAA adopt an airplane cabin carbon dioxide maximum concentration of 0.1
percent. Both commenters express concerns about the effect of higher
carbon dioxide levels and increased recirculation on the spread of
disease and on people with respiratory difficulties. One commenter
notes that concentrations above 0.1 percent may result in complications
for persons with an existing respiratory difficulty, noting that 12.4
million Americans have asthma.
Another commenter states that flight attendants who are repeatedly
exposed to carbon dioxide levels above 0.1 percent develop a tolerance,
while passengers do not. Another commenter states that flight
attendants are at a greater risk because of this same
[[Page 63954]]
repeated exposure. The FAA does not concur with these views. The
documented studies contained in the docket for this rule indicate that
the air quality currently present in the airliner cabins is comparable
to that found in other indoor environments. The OSHA recommendation
proposed in the Federal Register on April 5, 1994 (59 FR 16035), which
has not been adopted at this time, addresses the carbon dioxide
concentration as a comfort factor to be used in determining the need to
verify proper operation of heating and ventilating equipment. Further,
this proposal addresses non-industrial work environments and
specifically excludes vehicles. A copy of the OSHA proposed amendment
has been included in the docket for this rulemaking. There is no
evidence that concentrations up to 0.5 percent present any health
hazard in terms of general health or the spread of disease. In the
economic evaluation conducted by the FAA, the higher costs associated
with requiring a carbon dioxide concentration limit below 0.5 percent
do not present a favorable cost/benefit ratio and cannot be justified.
Further, there appears to be no specific concentration level, even at
levels down to 0.1 percent, at which at least some passengers might not
be affected. This rule, which will be contained in the airworthiness
requirements of part 25, is intended to provide safe flight and landing
for transport category airplanes. Because carbon dioxide in
concentrations below 0.5 percent do not have adverse safety effects,
the FAA has determined that a concentration limit of 0.5 percent
provides a reasonable balance between cost and benefit, and provides a
significant improvement over the existing allowable concentration.
Several commenters note that the OSHA and ACGIH standards are for
an average concentration over a specific time period. ACGIH, for
instance, recommends 5,000 ppm (0.5 percent) as a time-weighted average
for a normal 8-hour workday or a 40-hour workweek. They note in their
1991 report that Australia, Germany, Sweden, and the United Kingdom all
recommend a time-weighted value of 0.5 percent for carbon dioxide
concentration. OSHA's limits also reflect the average airborne exposure
in any 8-hour work shift of a 40-hour workweek. The FAA infers that the
commenters advocate providing both a time weighted and a short term
concentration limit. The FAA does not concur that the carbon dioxide
level should be averaged over the entire flight for several reasons.
Many flights exceed eight hours in duration, and the occupants are not
able to leave the airplane as are workers in an office. Also, there are
added stresses involved in being in an airplane cabin. The cabin
pressure altitude is significantly above sea level, usually at 6,000 to
8,000 feet. The relative humidity is lower than is usually found in
ground-based environments. There are unquantified stresses associated
with being in a crowded airplane cabin. Many people experience anxiety
from the mere fact that they are aloft. While most of these factors
cannot be controlled, the FAA has determined that the present part 25
limit on carbon dioxide concentration does not reflect industry
standards and should be reduced accordingly.
One commenter suggests that the average concentration should be
limited to 0.5 percent, but ``a limit of 3 percent by volume (sea level
concentration) may be allowed for short term durations.'' The commenter
points out that the 3 percent limit for short term durations
corresponds to the short term exposure limit (STEL) adopted by the
ACGIH, and having two limits should be similar to the two limits on
cabin ozone concentration specified in Sec. 25.832. Again, the FAA does
not concur. The adverse health and safety effects of ozone are defined
in available literature and Sec. 25.832 of the FAR addresses that
concern. There appears to be no reason to phrase the two requirements
similarly.
The FAA has determined, however, that some short term excursions to
values higher than 0.5 percent at some locations in the airplane may
occur during normal, inflight operations when airplane pressurization
and air conditioning systems are controlling the environment in the
cabin. One commenter notes that the area in close proximity to the
galley may experience higher carbon dioxide levels because meals are
often cooled by dry ice, which releases gaseous carbon dioxide. Another
commenter states that cabin air can be contaminated on the ground by
exhaust ingestion or self ingestion during certain wind conditions. The
FAA does not agree that this presents a problem. In one survey,
conducted by the Harvard University School of Public Health, carbon
dioxide levels were measured during boarding and deboarding operations.
The typical levels reported were 2,000 to 2,550 ppm, or 0.2 to 0.25
percent, well below the 0.5 percent proposed by the FAA. However, the
FAA does concur that it is not appropriate for the certification
standards to apply to operations on the ground when the airplane
systems are not operating (e.g., at the gate or during ``push-back'').
The final rule is changed to reflect this determination.
The same commenter expresses concern that the use of carbon dioxide
hand-held fire extinguishers in the cabin could result in local
concentrations exceeding 0.5 percent, noting that the present Halon
extinguishers might be replaced by carbon dioxide devices now that
production of Halon is banned, and suggests a higher short-term
exposure limit. The FAA does not concur that this is a justification
for a higher limit. The use of carbon dioxide fire extinguishers is not
envisioned, although there are no prohibitions against their use in
airplanes. When Halon is no longer available, the replacement
extinguishers will be required to be safe in the concentrations
predicted for use in occupied areas. Further, the use of fire
extinguishers in the cabin is, by its nature, an emergency situation.
This is not, in the context of the previous paragraph, normal in-flight
operations. Therefore, there appears to be no need for the higher limit
on carbon dioxide.
Two commenters state that the utilization of building criteria for
establishing carbon dioxide concentration limits for airplane cabins is
not appropriate. Both commenters add that the statement in the proposal
that concentrations above 0.5 percent are hazardous is not justifiable.
The FAA concurs with the general statement that carbon dioxide
concentrations above 0.5 percent may not be hazardous for most people.
Many standards in use today allow higher concentrations. As noted by
one commenter, the World Health Organization considers 12,000 ppm (1.2
percent) to be a safe level. In any case, the final rule has been
changed and no longer contains the word ``hazardous.'' Both of these
commenters note that the rule, as proposed, would limit carbon dioxide
concentrations in lower lobe galleys, accessible cargo compartments
where animals are carried, cockpits, and other occupied areas. They
express concern that local carbon dioxide concentrations in the galley
areas where food is cooled with dry ice might exceed 0.5 percent. The
FAA concurs in part with these comments. The ventilation requirements
associated with this rule change are intended to address areas that are
normally occupied. Cargo compartments accessible in flight, whether in
all cargo or ``combi'' airplanes with main deck cargo compartments, are
not ``normally occupied.'' The final rule has been changed to reflect
this determination.
One commenter disagrees with the statement in the preamble of the
proposed rule that ``This low ventilation rate is also sufficient to
dissipate the water vapor * * *,'' noting that water
[[Page 63955]]
buildup in insulation blankets is significant with present airplane
fresh air inflow rates, especially in hot day ground conditions. The
FAA concurs and the statement has been removed from the preamble. In
stating this view, the commenter did not recommend any changes in the
rule.
One commenter states that the term ``sea level equivalent'' should
be clarified. The commenter suggests that the clarification include
technical and/or medical rationale, including referenced sources, and
provide an explanation of the methodology by which this value is to be
calculated. If this rationale is not provided, the commenter states
that the FAA should delete the phrase. The FAA does not concur that the
term ``sea level equivalent'' is not defined, although the definition
appears in reference to another gas. In FAA Advisory Circular 120-38,
``Transport Category Airplanes Cabin Ozone Concentrations,'' sea level
equivalent is defined as ``* * * concentration in ppmv referenced to
standard conditions of 25 deg. C and 760 millimeters of mercury
pressure.'' Based on this definition, and calculations provided in the
AC, the maximum measured concentration, sea level equivalent, for a
cabin altitude of 8,000 feet would be 0.5 percent multiplied by 0.74
(the ratio of air pressure at 8,000 feet to air pressure at sea level),
or 0.37 percent. Values of this ratio for other cabin altitudes are
provided in the AC. As the term sea level equivalent is defined, the
rule is adopted as proposed.
The same commenter also notes that the statement in the preamble
that control of carbon dioxide buildup due to respiration is the factor
that dictates the design parameters for ventilation systems is
incorrect. Operation on the ground during high ambient temperatures
generally dictates the ventilation system design parameters. The FAA
concurs and the preamble has been changed accordingly.
One commenter recommends that the new standards for carbon dioxide
concentration not be applied to all-cargo airplanes. The commenter
notes that measured carbon dioxide levels on the flight decks of these
airplanes are well below both the current standard and that proposed in
Notice 94-14. The commenter goes on to state that lowering the limit on
carbon dioxide is a comfort issue, and would place a burden on the
manufacturers of transport category airplanes that is not commensurate
with any safety benefit that might result. The FAA does not concur. As
noted elsewhere in this preamble, the FAA has determined that the
existing concentration limit of 3 percent for carbon dioxide is not
appropriate because many passengers and crewmembers are adversely
affected at that level. The lower levels adopted by this amendment will
provide a standard that, when met, will ensure that passengers and
crewmembers, including those on all-cargo airplanes, will not be
subjected to levels of carbon dioxide that would reduce their ability
to perform their assigned duties. There are no costs associated with
lowering the limit as proposed.
With the exception of the changes noted above, this final rule is
adopted as proposed in Notice 94-14.
Regulatory Evaluation
Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 directs Federal agencies to
promulgate new regulations or modify existing regulations only if the
potential benefits to society justify its costs. Second, the Regulatory
Flexibility Act of 1980 requires agencies to analyze the economic
impact of regulatory changes on small entities. Finally, the Office of
Management and Budget directs agencies to assess the effects of
regulatory changes on international trade. In conducting these
assessments, the FAA has determined that this rule: (1) will generate
benefits exceeding its costs and is not ``significant'' as defined in
Executive Order 12866; (2) is not ``significant'' as defined in DOT's
Policies and Procedures; (3) will not have a significant impact on a
substantial number of small entities; and (4) will not constitute a
barrier to international trade. These analyses, available in the
docket, are summarized below, following FAA's disposition of comments
on the economic aspects of the NPRM.
Response to Comments
One commenter calculates that it would cost about $0.076 per person
per hour to provide 100 percent fresh air in the cabin of a typical
300-seat widebody airplane. The FAA disagrees with this commenter and
estimates that the cost of 100 percent fresh air would be $0.095 per
person per hour.
Another commenter states that the FAA did not account for the
potential costs of applying the rule to all occupiable sections of the
airplane because it evaluated only the passenger cabin area and ignored
the flight deck and lower lobe galleys. The FAA concurs in part with
this comment. The carbon dioxide concentration requirements are
intended to apply to areas that are normally occupied. The final rule
has been changed to reflect this intent. Thus, the commenter's
statement does not alter the FAA's economic analysis.
Another commenter states that the FAA did not evaluate the
possibility that ground-air contamination (ingestion of other
airplanes' exhausts) may temporarily push the CO2 level above the
0.5 percent limit. The FAA does not agree that this presents a problem.
In one survey, conducted by the Harvard University School of Public
Health, CO2 levels were measured during boarding and deboarding
operations. The typical levels reported were 0.2 percent to 0.25
percent, well below the 0.5 percent in this rule. However, the FAA does
concur that it is not appropriate for the certification standards to
apply to ground operations when the airplane systems are not
functioning. As a result, the final rule has been changed to reflect
this determination. Consequently, there is no economic impact as a
result of this remote possibility.
Two commenters state that if live animal cargo areas are included
under the definition of ``inhabited'' areas, there would be
considerable potential costs. The FAA partly concurs with these
comments in that cargo compartments accessible in flight, whether in
all cargo or ``combi'' airplanes with main deck cargo compartments, are
not normally occupied and the final rule has been changed to reflect
this determination. As a result, there is no economic impact from
excluding live animal cargo areas from this rule.
Costs
Airplane cabin CO2 levels can be reliably calculated from the
number of passengers and the ventilation rate. In addition, engineering
analyses have determined the amount of fuel used to provide a unit
ventilation rate. These functional relationships allow the calculation
of the costs to maintain a given cabin CO2 level. The FAA
estimates that the 3 percent CO2 limit under the current rule
costs about 0.27 cents per person per hour while the new 0.5 percent
limit will cost about 1.7 cents per person per hour. Thus, the amended
limit constitutes a 1.43 cent increase per person per hour, or about
$4,475 per (newly certificated) airplane per year.
In point of fact, however, the ventilation rates in current
transport category airplanes currently maintain cabin CO2 levels
below 0.5 percent. As the FAA expects that the minimum ventilation
rates of future aircraft designs will also maintain CO2 levels
below 0.5 percent in order to control
[[Page 63956]]
odors, temperature, water vapor, etc., no actual incremental costs or
benefits will result from the rule change. However, codification of
this limit will ensure that future designs maintain the 0.5 percent
level.
Benefits
Although outdoor air contains CO2 at the 0.03 percent level,
CO2 may produce respiratory center stimulation, mild narcotic
effects, and asphyxiation under high levels and high exposure duration.
At concentrations of 2 to 3 percent, CO2 can produce headaches,
breathing difficulty, and increases in blood pressure and pulse. By
comparison, no ill-effects have been observed at the 0.5 percent level.
Cost-Benefit Comparison
From a strict cost-benefit evaluation of the rule change itself,
isolated from actual practice, the FAA concludes that it would cost
about 1.43 cents per person per hour to increase the ventilation to
reduce cabin CO2 levels from 3 percent to 0.5 percent. By
comparison, this reduction eliminates the cabin CO2 levels known
to produce headaches, breathing difficulty, and increases in blood
pressure and pulse. While no precise economic value has been assigned
to the benefit from avoiding these ill effects, the FAA has determined
that they are worth more than 1.43 cents per person per hour.
Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) was enacted by
Congress to ensure that small entities are not unnecessarily or
disproportionately burdened by Government regulations. The RFA requires
a Regulatory Flexibility Analysis if a proposed or final rule would
have a significant economic impact, either detrimental or beneficial,
on a substantial number of small entities. FAA Order 2100.14A,
Regulatory Flexibility Criteria and Guidance, prescribes standards for
complying with RFA review requirements in FAA rulemaking actions. The
Order defines ``small entities'' in terms of size, ``significant
economic impact'' in terms of annualized costs, and ``substantial
number'' as eleven or more and which is more than one-third of the
small entities subject to the proposed or final rule.
The final rule would affect manufacturers of transport category
airplanes produced under future new airplane type certificates. For
manufacturers, Order 2100.14A defines a small entity as one with 75 or
fewer employees. Since no part 25 airplane manufacturer has 75 or fewer
employees, the rule would not have a significant economic impact on a
substantial number of small entities.
International Trade Impact Assessment
As the certification rules apply to both foreign and domestic
manufacturers that market airplanes in the United States, neither group
will receive a competitive advantage. As no incremental compliance
costs are expected, there will be no competitive trade disadvantage or
advantage for U.S. manufacturers in foreign markets or for foreign
manufacturers in the United States.
Federalism Implications
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule will not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
International Civil Aviation Organization (ICAO) and Joint Aviation
Regulations
In keeping with U.S. obligations under the Convention on
International Civil Aviation , it is FAA policy to comply with ICAO
Standards and Recommended Practices to the maximum extent practicable.
The FAA has determined that this rule does not conflict with any
international agreement of the United States.
Paperwork Reduction Act
In accordance with the Paperwork Reduction Act of 1990 (44 U.S.C.
3501 et seq.), there are no reporting or recordkeeping requirements
associated with this rule.
Conclusion
Because the revised standards for maximum allowable carbon dioxide
concentration are not expected to result in a substantial economic cost
or have a significant adverse effect on competition, the FAA has
determined that this final rule is not significant under Executive
Order 12866. In addition, the FAA has determined that this action is
not significant as defined in Department of Transportation Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). Since no
actual incremental costs are expected to be incurred to comply with the
requirements of this rule, the FAA certifies, under the criteria of the
Regulatory Flexibility Act, that this regulation will not have a
significant economic impact, positive or negative, on a substantial
number of small entities. A copy of the regulatory evaluation prepared
for this final rule has been placed in the public docket. A copy may be
obtained from the person identified under the caption, FOR FURTHER
INFORMATION CONTACT.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Adoption of the Amendment
In consideration of the foregoing, the Federal Aviation
Administration (FAA) amends 14 CFR part 25 of the Federal Aviation
Regulations (FAR) as follows:
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
1. The authority citation for part 25 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.
2. Section 25.831 is amended by revising paragraph (b)(2) to read
as follows:
Sec. 25.831 Ventilation.
* * * * *
(b) * * *
(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.
* * * * *
Issued in Washington, D.C., on November 21, 1996.
Linda Hall Daschle,
Acting Administrator.
[FR Doc. 96-30525 Filed 11-29-96; 8:45 am]
BILLING CODE 4910-13-P
