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About Aviation Medicine


What is Aviation Medicine?

Aviation Medicine is a medical specialty which combines aspects of preventive, occupational, environmental and clinical medicine with the physiology and psychology of man in flight. It is concerned with the health and safety of those who fly; crew and passengers; as well as the selection and performance of those who hold aviation licenses.

Travel by air:

Air travel; particularly long-distance travel, exposes passengers to a number of factors that may adversely affect their health and well-being. Passengers with pre-existing health problems may find that they are more susceptible to these factors. Health risks associated with air travel can be minimized if the traveler plans carefully and takes some precautions before, during and after the flight. An explanation of the various factors that may affect the health and well-being of air travelers follows:

Cabin air pressure:

Although aircraft cabins are pressurised, cabin air pressure at cruising altitude is lower than air pressure at sea level. At a typical cruising altitude of 11 000 meters (37 feet), air pressure in the cabin is equivalent to that at an altitude of 1 500 - 2 500 meters (5 000 - 8000 feet) above sea level. As a consequence, the available oxygen is reduced and gases within the body expand. The effect of reduced cabin air pressure are usually well tolerated by healthy passengers.

Oxygen and hypoxia:

During all stages of flight, cabin air contains ample oxygen for healthy passengers. However, because cabin air pressure is relatively low, the oxygen saturation of the blood is slightly reduced, leading to mild hypoxia (i.e. reduced supply of oxygen to the tissues). Passengers with cardiovascular or respiratory disease, or certain disorder of the blood such as anaemia or sickle cell disease, may not tolerate hypoxia well. Moreover, the effect of alcohol on the brain is increased by hypoxia.

Gas expansion:

Air expands in all air-filled body cavities as a result of the reduced cabin air pressure. Abdominal gas expansion may cause moderate discomfort, which may be exacerbated by consumption of carbonated beverages and certain vegetables. As the aircraft ascends, air escapes from the middle ear and the sinuses, usually without causing problems. As the aircraft descends air must be allowed to flow back into the middle ear and sinuses in order to equalize pressure differences ("clearing the ears").

Most discomfort can be alleviated by swallowing, chewing or yawning; if the problem persists, forcefully expiration against a closed nose and mouth will usually help. For infants, feeding or giving a pacifier to stimulate swallowing may reduce the symptoms.

People with ear, nose and sinus infection should avoid flying because pain and injury may result from the inability to equalize pressure differences. If travel cannot be avoided and problems arise during flight, decongestant nasal drops may be helpful.

Individuals who have recently undergone certain types of surgery should not fly for a period of time because of possible damage resulting from gas expansion.

Cabin humidity:

The relative humidity in aircraft cabins is low, usually less than 20%. Low humidity may cause discomfort of the eyes, mouth and nose but presents little risk to health. Discomfort can be alleviated by maintaining good fluid intake before and during the flight, using a skin-moisturising lotion, using a saline nasal spray to moisturise the nasal passages and wearing spectacles rather than contact lenses.

Dehydration:

Measures should be taken to prevent dehydration during long flights. Fluids intake should consist of non-alcoholic beverages (water and fruit-juices) both before and throughout the flight. As alcohol contributes to dehydration, consumption of alcohol should be restricted, and preferably avoided before and during the flight.

Ozone and cosmic radiation:

The concentration of ozone (triatomic oxygen, O3) and the intensity of cosmic radiation both increase with altitude. Ozone is easily converted to oxygen by heat and various catalytic processes. In modern jet aircraft, almost all ozone in the ambient air is converted to oxygen in the compressors that provide pressurized air for the cabin.

During descent, when engine power is low, a build-up of ozone is prevented by catalytic converters. At usual cruising altitudes, the concentration of ozone in the cabin air is negligible. Cosmic radiation is the sum of solar and galactic radiation. At aviation altitudes, the cosmic ray field consists of high energy-ionizing radiation and neutrons. The atmosphere and the earth's magnetic field are natural shields. Because of the orientation of the magnetic field and the "flattening" of the atmosphere over the North and South Poles, the cosmic radiation levels are significantly higher at polar than at equatorial latitudes. The intensity of cosmic radiation levels increases with altitude and dose rates of 1 â€" 3 microSv/hour on short haul and 5microSv/hour on long haul rotes are typical. For comparison, the natural background radiation from soil, water and building materials is about 2microSv per year in most countries.

The International Commission on Radiological Protection has set 1mSv per year as a basic safety standard for the protection of the health of the general public against the dangers arising from additional ionizing radiation.

 

Function of the Aviation Medicine Department

The functions of the SACAA Aviation Medicine Department are:

  1. Medical Certification of Aviation Personnel (Part 67 of the Civil Aviation and Technical Standards.
  2. Oversight of the Collaborative Arrangement for the Prevention and Management of Public Health Events in Civil Aviation (CAPSCA)-(Part 64 91,121, 113,139 of the Civil Aviation and Technical Standards.
  3. Oversight of Air Ambulances (Part 138 of the Civil Aviation and Technical Standards).
  4. Oversight of First Aid Cabin Crew Training(Part 64 of the Civil Aviation and Technical Standards

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