How aerial travel and Cabin Pressure adversely affects the Human Body

AS and A Level Science

IB Group 4 project (Biology)

IB Biology 1 HL Group 4 Project

Agreed Topic: Transportation

Grade 11

December 2003 - January 2004

Effects of Traveling in an Airplane and the Effects of Travel into Space on the Human Body

The idea of humans traveling to the Moon or other areas out side of the Earth’s orbit is mostly scientific. However, when astronauts remain in space, having to re-balance the body to suit less or no gravity compared to the Earth could bring about many changes to the body. Scientists have found that the time required for recovery depends on the time spent in zero-gravity conditions. The longer one stays off of the Earth’s surface, the more damage can be caused. Strictly speaking, even a trip in an Airplane would require safety precautions to minimize damage to the body of this. For example, cabin pressure increased to maintain balance and prevent feeling different to a lower pressure. This essay will consist of two sections. The first will be of flight effects within the Earth’s hemisphere, and how to perhaps prevent damage to the body. The second, and longer section deals with space travel through Zero-gravity and effects of weightlessness on the body and the counter-measures to prevent damage to the body.

Section 1, flight effects on the passengers, specifically dealing with cabin pressure:

Airplanes fly at the cruising altitude of around 33’000 feet, or approximately 10’000 meters. Because the cruising altitude has a cabin pressure lower than air pressure on ground or even under sea-level, the oxygen availability is less and gases within the body expand. This causes the oxygen saturation level of the blood to reduce, which can lead to mild hypoxia, the reduced supply of oxygen to the tissues around the body. Due to the effects of hypoxia, alcohol consumption would affect the brain much more than it would on Earth.

As the aircraft makes its decent back to Earth, air must be allowed to flow into the middle of the ear to equalize pressure differences. Passengers often can feel this change in air pressure. People with ear, nose and sinus infections are usually advised to avoid flying because of these changes in air pressure.

Air travel in airplanes has less thank 20% humidity. This causes discomfort to the eyes, mouth and nose but does not risk the passenger’s health. This discomfort can be prevented by drinking liquids (water recommended) before and during the flight, and using skin moisturizers. Also passengers with short-sightedness or long-sightedness are advised to wear eye-glasses rather than contact lenses during flight as the contact lenses may dry out. In order to avoid de-hydration, passengers should drink non- alcoholic beverages.

Section 2, how traveling through space affects humans

Astronauts often experience “Zero- Gravity” during their travels through space. This zero gravity or micro gravity can bring about health concern to the body if astronauts remain in space for a long period of time. It would be much healthier for crews to live under artificial gravity.

This is a preview of the whole essay

Section 2, how traveling through space affects humans

In order to prevent any biological changes in the body when experiencing zero gravity, scientists recommend a force of artificial gravity equal to a third of the Earth’s level of gravity. However, scientists still haven’t research affects of artificial gravity on humans but they know for a fact and there is an imbalance in the body due to the shifts of gravity levels. Artificial gravity prevents physiological changes from occurring. In zero-gravity, the body deteriorates.

It takes less muscle to move around, so after a long period of time in space, muscles weaken so the body bends. Because there is no tension in space, muscles relax and after a while they atrophy as a result of disuse and eventually disappear. To prevent the fracture of bones, limbs and muscles, all space shuttles give the opportunity for astronauts to do rigorous exercise everyday to keep the muscles strong.

Staying in Zero-gravity for months causes bones to lose mass and get thinner, as they are not carrying any weight. This means astronauts must go through rigorous trainings in the spacecraft everyday in order to keep muscle and bone strength. “When a great deal of the crew’s precious time in space is spent exercising rather than doing science, money and potential knowledge are being squandered for the sake of health. It is a sacrifice, but a necessary one”

In space, receptors in the inner ear allow humans to sense direction. In space, ear receptors don’t receive the same cues and the mind gets used to ignoring the inner ear’s feelings about balance. Hand-eye coordination, posture and balance are all affected by the disorientation of the mind. When astronauts return to earth, they are often “overwhelmed by dizziness” and have difficulty in maintaining balance. An example of the mind adapting to the new gravity less surroundings would be with Shannon Lucid, who was on board the Russian space Station MIR for six months. The astronaut said “You just sort of get used to floating around” but we also know that floating around is not all that astronauts do- they must resist the effects of micro gravity on the body.

Also, no gravity means no resistance from growing, so some astronauts return to earth some 6 inches taller than when they left. It is only after a few months that they grow down/ shrink back to normal height. This is because of the unloading of spinal discs- because of lack of gravity, the discs in the spine are not holding up or don anything, so they tend to stretch rather than contract.

Traveling through micro gravity causes bodily fluids to shift from the lower body to the cephalic area (head), and so people’s faces tend to swell and become rounder than they are on earth. When the brain senses a higher amount of blood than usual, it interprets the situation that there is now an overall increase in the total volume of fluids in the body. The brain responds by triggering the excretion of fluids, making astronauts prone to dehydration. Also, the fluid redistribution can shrink legs as the bones are weaker. These fluids pass through the kidneys, causing kidney filtration rate to increase, bone loss can cause Kidney stones. Fluids that leave the body include calcium loss and bone demineralization. The loss of blood plasma causes temporary Anemia upon the return to Earth. Some crew members get “space anemia.” Scientists are concerned about the affects of catching this disease on over all crew performance. Blood volume may decrease by 10 percent.

The increase of fluids in the head causes the same feeling as when one has a cold and feels blocked in. in space astronauts begin to lose their sense of taste, causing the craving for strong flavorings in the food such as horseradish, mustard and taco sauce. Fluid loss, lack of exercise and diminished appetite cause weight loss as astronauts tend not to eat as much as they would on earth. Meals and exercise are planned to prevent excessive loss.

Zero-gravity affects the cardio-vascular system. On earth we must cope with gravity, which sustains or slows down the blood-flow. In zero gravity, there is no gravity force, causing the heart to slow down due to the decreased demands of blood as it travels more freely.

The immune system in the body is also affected by weightlessness. In space, one is exposed to illness as the immune response lowers and numbers of anti-bodies decrease after a long exposure to micro gravity. Approximately half of all astronauts are affected by this unpleasant syndrome which affects nausea, headache, lethargy and sweating (taken from NASA sources). Also, minor effects of weightlessness on the body include puffiness in the face, flatulence, weight loss, nasal congestion and often sleeping disturbances.

Upon returning to earth, recovery time depends on the duration of stay in space. Muscles are weak and the body is not used to gravity forces, (causing them to feel dizzy) and so some astronauts are taken back in stretchers. This shows why astronauts need to be “at the peak of fitness.”

If in the near future the human race would build space stations as tourist resorts, some would prefer hotels with zero-gravity and some would want partial gravity, which would bring about competition like hotels on earth, which would drive prices low. As gravity affects all biological, physical and chemical processes on earth, building an International Space Station gives new opportunity to study a world without gravity and its affect on animals and other living organisms. Observing the weightlessness effect on these living organisms could teach scientists about biological processes on earth, such as aging and osteoporosis.

In the end, we can see that human travel through space is safer under artificial gravity when compared to astronauts being exposed to weightlessness, micro gravity or zero gravity (all three mean the same). Most of the problems mentioned such as fluid loss and muscle deterioration would not cause problems as long as the crew remained in a weightless environment. Remaining in a zero-gravity environment for over a long period of time could cause problems, however. In 1987, in the later stages of his 326-day mission, Russian Yuri Romanenko was fatigued both physically and mentally due to traveling through space. The majority of his day was spent sleeping regaining strength, in the meantime his bones were deteriorating. Some say if many like Romanenko stayed in space for much longer, he may not have survived re-entry to the Earth. Returning to Earth could cause problems as the body is much weaker due to demineralization and atrophy of the bones and shortage of red blood cells. One’s balance must now again be readjusted causing many astronauts to feel dizzy when back to a strong “g” force gravity on earth.

Whether or not the large amount of time and money spent on keeping astronauts fit during space flight is worth the scientific findings is debatable. Physiological effects need to be prevented as much a possible. Again, this is usually prevented by rigorous exercise and micro gravity could still be a danger to the astronaut’s health. Many scientists believe that the benefits of transporting/sending out machines (robots) and humans to space, despite the health issues, are nothing compared to the huge benefit that society will receive. Humans will not be perfectly suited to living in a weightless environment, but that won’t stop Astrobiologists and many other research firms like NASA from exploring space. The many benefits of space exploration such as technological knowledge and inspiration easily outweigh the negative aspects.

Total word count excluding diagram: 1837 words

Bibliography:

Sources were from Newspapers, CDs, web sites and a large extract of a book in one of the web-pages. Most web sites accessed on the 11th December 2003 and 9th January 2004.