COMMERCIAL AND BUSINESS
AVIATION ADVISORY CIRCULAR
No. 0185
2001.06.11
The Effect of Beards or Long Hair on the Efficiency of Demand Type, Continuous Flow Oxygen Masks, or Smoke Hoods
INTRODUCTION
The purpose of this Commercial and Business Aviation Advisory Circular (CBAAC) is to inform air operators of the effect of beards, heavy facial hair or long hair on the efficiency of respirator/oxygen (demand type), continuous flow oxygen masks and smoke hoods provided on board aircraft for use by crew members.
REFERENCES
- Sections 605.31, 605.32, 703.67, 703.68, 704.66, 704.67, 705.94, 705.71 and 705.72 of the Canadian Aviation Regulations (CARs);
- Aviation Occupational Health and Safety Regulations (aircraft) 6.8(1) and Canadian Standardization Association Standard Z94.4-M1982;
- Federal Aviation Administration (FAA) Advisory Circular (AC) No. 120-43;
- Technical Standard Orders (TSO) C78, C89, C99 and C116.
BACKGROUND
Some years ago and following several reports of possible problems with oxygen mask efficiency when used by persons with beards, the Civil Aeromedical Institute (CAMI) at the U.S. Federal Aviation Administration's Protection and Survival Laboratory investigated the effects of beards on oxygen mask performance.
Demand type mask
The CAMI research involved testing of three popular Technical Standard Orders (TSO) approved crew member oxygen masks equipped with mask mounted regulators, each of which is widely used in civil aviation operations.
The test data indicated that a decrease in performance does occur when facial hair is present along the sealing surface of the crew oxygen masks. The decrease in efficiency is proportional to the amount of facial hair present, the type of mask worn, the suspension system associated with the mask, and the exercise level to which the individual is subjected. The study, like studies conducted previously by oxygen equipment manufacturers and the U.S. military, concluded that respirator/oxygen (sometimes referred to as "demand type") masks cannot be donned rapidly and do not seal over beards or heavy facial hair. This lack of a seal could result in a reduction in the amount of oxygen in the mask and the entry of smoke or toxic fumes that could reduce the capability and performance of the crew member.
Continuous flow mask
Additional research was conducted on the effect of beards on the efficiency of passenger continuous flow oxygen masks of the type used to provide protection from hypoxia in the event of decompression. Again, three types of masks were tested of which two were TSO-approved.
The test data indicated that the presence of beards adversely affects the efficiency of continuous flow oxygen masks. The researchers found that the leakage of ambient air caused by beards does not permit an adequate percentage of oxygen to be presented to the lower portion of the respiratory tract.
The proper functioning of the continuous flow mask relies on having the greatest concentration of oxygen presented at the beginning of inspiration with dilution of oxygen permitted during the latter phase of inspiration. The concentration of oxygen and the inspiration phase during which it is inhaled are more critical factors than the total oxygen received.
The researchers concluded that bearded passengers using these continuous flow masks might expect some deficit in oxygenation following decompression that could lead to varying degrees of hypoxia. If the mask is properly donned and usual emergency descent procedures can be followed, the deficit in oxygenation might not be severe enough to be life threatening but could cause loss of consciousness.
Flight attendants are more physically active than passengers during flight and this results in an increased respiratory exchange rate. Earlier studies have already shown that physical activity representative of flight attendant duties reduces the time of useful consciousness by about 40 percent over that of a resting individual. Other data collected by CAMI indicates that bearded individuals with the highest respiratory exchange rate experienced the greatest degradation in oxygenation. Thus, the combination of the increase in respiratory exchange rate and decrease in efficiency of an oxygen mask when worn by a bearded flight attendant could result in that individual being impaired in the performance of their assigned safety related duties.
Smoke Hoods
Data obtained from tests on smoke hood type protective breathing equipment has identified that leakage is likely to occur if a proper seal at the neck is not obtained. A beard that extends down the neck or hair that extends below chin level can interfere with the integrity of the neck seal with the result that the efficiency of the smoke hood is compromised.
POLICY DEVELOPMENT
Air operators are advised to ensure that their crew members are made aware of the following:
- demand masks, such as those used in protective breathing equipment, often cannot be donned rapidly, nor seal effectively when used by bearded persons or persons with heavy facial hair. This can adversely affect the performance of the mask and reduce crew member awareness, capability and performance;
- a flight attendant's job-related physical activity reduces the time of useful consciousness and increases respiratory exchange rates. These factors, combined with the reduced efficiency of continuous flow oxygen masks that is associated with beards, could produce physiological symptoms that might reduce the flight attendant's ability to perform their safety related duties following a decompression; and
- the efficiency of smoke hood style protective breathing equipment is considerably decreased if a firm neck seal is not established and maintained. A beard that extends down the neck or the presence of long hair in the neck seal area, can render the neck seal susceptible to leakage thus affecting the efficiency of the smoke hood.
CONCLUSION
It is important that crew members are made aware that the presence of beards, heavy facial hair or long hair can have an adverse effect on the efficiency of respirator/oxygen (demand type) oxygen masks, continuous flow oxygen masks or smoke hoods provided on board aircraft for use by crew members. Air operators should take the content of this CBAAC into consideration when establishing procedures and policies for inclusion in their Operations Manuals, Flight Attendant Manuals and Training Programs.
M.R. Preuss
Director
Commercial & Business Aviation
Commercial & Business Aviation Advisory Circulars (CBAAC) are intended to provide information and guidance regarding operational matters. A CBAAC may describe an acceptable, but not the only, means of demonstrating compliance with existing regulations. CBAACs in and of themselves do not change, create any additional, authorize changes in, or permit deviations from regulatory requirements.