 During the period of recorded history, there is little evidence to indicate that man has changed in any major respect. Among living creatures, he is not the strongest or the fastest, but rather a unique compromise. If we were to look at man as if he were a machine, we would say that he is made of three interrelated parts. First, he is a physical structure. Second, he is a biochemical laboratory. Third, he is an emotional, psychological computing device. Although modern man's aspirations carry him into new and hostile environments, he is essentially the same as he has always been. His mechanical, chemical, and psychological abilities are severely limited. When the demands of the situation exceed these limits, man breaks down. The result? An accident. Physiological man is a ground animal, and in the early days of the American farmer, he had little reason to think about himself as a biochemical laboratory. He lived in a relatively simple civilization, and most of his needs were met by simple means. He got plenty of sunshine and fresh air. His water was good to drink, and he grew most of his own food. He put in a hard day's work, but he got plenty of rest. Except for periods of illness when his biochemical laboratory broke down as a result of disease, he lived, at least according to some romantic versions of history, a short but happy life. But man's incredible ingenuity and his insatiable lust for pioneering changed all that. Now there appears to be more automobile exhaust and industrial waste than fresh air. The work is easier, and he gets most of it done sitting down. He has plenty of leisure time, but gets very little rest. His periods of illness are more frequent, but less devastating, and his biochemical laboratory seldom breaks down completely, but gradually wears away. So that he lives, at least according to the contemporary novel, a long but miserable life. Although his tools are more complex, their operation is simple, scanning lights, throwing switches, and pushing buttons. The work is easier, but he lives in a highly dangerous environment. If he wants to stay alive, if he wants to prevent accidents, he must not only take technical precautions, but he must understand his own internal physiological limits. Man is highly complicated, and it would take an elaborate chemical laboratory to reproduce the biochemical actions taking place in his body. So to put it simply, when the blood is pumped through the body adequately and contains the proper chemicals, his body structures are nourished. His sensory apparatus remains acute. He can arrive at clear-cut decisions and take efficient action. If this biochemical balance is upset, dangerous inefficiency results. Man's most immediate chemical need is for the oxygen in the atmosphere. Without it, life can be sustained only a matter of minutes. He needs oxygen for the production of energy. He takes it into his lungs, and from there, it goes into his blood. While the unwanted waste product, carbon dioxide, comes out of the blood and is discharged into the air. The bloodstream carries the oxygen to the hungry tissues. Some toxic gases, however, can prevent man from getting enough oxygen. The most common is carbon monoxide. Taken into the lungs, it prevents the oxygen from being carried by the blood, depriving the tissues of nourishment. Early stages of oxygen deficiency can induce a feeling of well-being and render man incapable of perceiving his impaired abilities. Increased amounts of this toxic gas can lead to asphyxiation, unconsciousness, and ultimately death. The modern world requires man to handle toxic materials, both industrially and in daily life, with a deadly over familiarity. Poisoning is common in man's daily life, not only in a highly dramatic way, but also by small insidious doses, deadly because they damage the body tissues and retard or inhibit man's reactions and judgment. These poisons can enter his body through the respiratory tract, or by the way of skin absorption into his bloodstream, or they may enter through his gastrointestinal tract, where they can cause injury to visceral organs such as liver and kidneys. They may affect the blood-forming system in his bone marrow. Man, sometimes unwittingly, sometimes deliberately, uses one of the most common systemic poisons, ethyl alcohol. The primary ingredient of alcoholic beverages. What he hopes will be a stimulant turns out to be a depressant. Ethyl alcohol acts like an anesthetic or narcotic. It can depress the nervous system, eventually causing pain, tremors, acute hallucinations, and general personality deterioration, even psychosis. Proper nourishment is essential. Without it, the tissues may become dehydrated. Waste products build up in the bloodstream with nothing to displace them. The blood flows like a sluggish stream full of mud and debris, barely moving. This reduces man's efficiency and causes errors in his judgment. Similar malfunctions of man's body can occur during illness, and even medication may be a contributing factor. And this can be further complicated by self-medication. Perhaps one of the most frequently violated limits of man is his need for rest. Fatigue probably causes and contributes to more accidents than any other single factor. Fatigue may be brought on by either too much or too little physical activity. Efficiency decreases and man tolerates errors much more readily and even fails to see that errors have been committed. After 48 to 72 hours without sleep, the body becomes extremely inefficient. Man grows highly irritable and he is apt to fall asleep involuntarily at any moment. Man used to work and live among rather simple external hazards. But now he ventures into more hostile environments for which he is poorly constructed. Man's body is built to function under the pressure of the atmosphere at sea level. Lack of pressure at high altitude can cause the release of gas bubbles as the liquids in his body evaporate. In effect, they boil and this may lead to collapse. Even his breathing 100% oxygen cannot prevent it. Too much pressure creates a crushing effect, such as experience by an astronaut under the force of great acceleration. These G-forces cause incapacitation by slowing down or stopping the flow of blood. Although excessive heat or cold can destroy body cells, man can, with the aid of his technical skill, function over a wider range of temperature than any other animal. But no matter where he exists, he must maintain a constant body temperature of 98.6 degrees. A rise of 5 degrees results in high fever, possible delirium. A rise of only 3 more degrees and death may result. Man travels freely only within very narrow margins of pressure and temperature. He is further limited by his need for fuel, being able to survive about 30 days without food, 3 days without water, and little over 3 minutes without oxygen. It is indeed a small cage within which man lives, confined by pressure, temperature, and fuel limitations. By fantastic technical skill, however, man has succeeded in expanding his living working area into outer space. Here failures in body chemistry become even more critical. The physiological limits of man are constantly being tested, measured, and evaluated. Today, great task forces of scientists are at work, creating and developing a ground environment for man to take with him. When he leaves the earth in a capsule, or penetrates it in a silo, so that man may live and work under these extreme conditions, the scientists create systems that will provide him with the proper amount of oxygen that will minimize the effects of toxic substances. The disabling effects of G-forces, systems that will control atmospheric temperature, humidity, purity and pressure, provide him with the proper nourishment, and warn him of radiation and other hazards. All these systems are created to arm man with the most effective equipment science can devise to prevent his physiological limits from being violated, to protect him against himself. In spite of all the exacting scientific calculations, there will be accidents, not only here in these unique environments, but on the ground. For dangers lurk everywhere in modern civilization, and every man should know the danger areas in his own external environment. They may not look dangerous, but they are insidious. There are lethal toxic substances in paint and gasoline vapors, as well as in highly corrosive acids and missile fuels. There are dangers to the body cells from excessive heat and cold, as well as from electromagnetic equipment. Danger from oxygen and pressure in scuba diving, as well as in flying at altitudes over 10,000 feet. Danger from high pressure in a big fat aircraft tire, as well as in a skinny helium line. In an electric storm on a golf course, as well as in a silo power box. Every man should also know the dangers to his internal environment. Temptations to biochemical disaster from alcohol, from improper foods and food substitutes, from a great variety of medicines, antihistamines and tranquilizers, and fatigue. I came off a long and delayed mission, released at 2300. A message was waiting for me. My aunt and uncle wanted to see me right away. You never know whether it's serious or not, so I drove right out to their house. You see, I'm a long way from my hometown, and they feel they have to do something to keep me cheered up. They'd invited a lovely looking girl over to meet me, and she'd been waiting here all that time. I admit it was kind of pleasant, and I enjoyed meeting her. But we sat around till three in the morning. I was halfway home, and I could feel myself going to sleep. I kept saying only three more miles to go. The last thing I remembered was a slow-moving, oncoming car with just one very bright light. I thought I'd pulled over to the right-hand side of the road. When he saw the picture of his car a week later, he didn't believe it. The car had crossed the center line and gone off the left side of the road and plowed into a palm tree. Then he remembered he had fallen asleep. Whenever man's physiological limits are violated, the result is inevitable. Injury or death. I was flying the front seat of an F-100F. The mission had gone well. Rear pilot and I both felt we'd done a real fine job. He was in the habit of taking off his mask to enjoy that well-earned cigarette. And that's what he was doing when it happened. We were at 29,000 feet when, without warning, I looked back for a split second, and saw his scarf blowing around. I sensed he was in trouble. I declared an emergency and let down as fast as I could. I managed to land the aircraft safely. Apparently when the canopy blew, his scarf had become entangled in his headrest because of the slipstream and had strangled him to death. One ugly fact stands out. He didn't have his oxygen mask on at the time of decompression. He never had a chance to untangle that scarf. He was unconscious in less than two minutes from lack of oxygen. You don't have to be at 29,000 feet to suffer from lack of oxygen. It can happen on the ground. It happened to three of us right here on this pad. We were in the process of transferring liquid nitrogen and it's a miracle I was still alive to tell the story. You see, you get to know your crew pretty good at working on a dangerous operation like this. And you know your life may depend on the other guy. So it's understandable that at times of emergency we're a lot more than just a team. When someone spots trouble, he doesn't say let's go. He moves. By the time I looked around one of my men had already gone into the tank. And I could see vapors in the air. I knew something was wrong. But before I could do anything about it, this buddy went in after him. He didn't come out fast enough to suit me. I don't know why I didn't take time to grab an air pack, but in I went after them. There they were. Both lying on the floor, knocked out. I knew I only had a few seconds to get them out. It wasn't my heroics, but the fact that I held my breath until I shut out the valve that saved all our lives. The first man in happened to be the last man out and he was having convulsions. Fortunately, we all recovered. But the man who was in there the longest still has a pretty bad kidney. None of these men wore protective equipment. The Air Force spends millions of dollars developing it, and if you don't wear it, you can be dead wrong. But even wearing the protective equipment is not enough. There's no substitute for knowledge. A man has to know the signs of approaching danger before it's too late. I was getting a backseat ride to observe some high altitude practice intercept missions. When the pilot noticed that we didn't have pressurization at about 28,000 feet. Because nothing else seemed to be wrong, we decided to continue. While passing through 36,000 feet, I felt pain at the base of my neck and a little gas in my stomach. I still thought we could go on unless it got worse. At 40,000 feet, it did. Pain shot through my shoulder and neck like a hot poker. My vision was blurred. The gas pains doubled me up. From that point on, things went black. Rest at ground level wasn't enough to revive me. So they put me under heavy pressure in a recompression chamber. I felt almost immediate relief. Then they gradually began bringing my body back to normal pressure. 36 hours later, that chamber had saved my life. Some things the body needs desperately to stay alive. But there are others it can very well do without. By midnight, the card game was over. We got a little restless and went into town. By the time we headed back to the base, a light fog had made driving difficult. We were feeling no pain. We were traveling at a pretty good speed. When several big trucks came across the bridge. Our driver moved off to the right a little too far. Then crashed into the bridge foundation. I was the only survivor. Alcohol is not a stimulant. It is a depressant. It plays havoc with your nervous system. It can't be said often enough. If you're going to drink, don't drive, don't work, stay home. It is not enough merely to know the physiological limits. The men in this aircraft knew they were violating almost every physiological limit in the book. They were on an extended mission and approximately one hour after take-off had experienced uncontrollable heat in the forward compartment. At times during the first 13 hours of flight, the crew was exposed to temperatures estimated at 125 to 160 degrees. It was hot and the cockpit was like a sweltering oven. You know the zipper on my flying suit was so hot it burned my fingers even through my gloves. The yoke could hardly be handled. Yet the decision had been made to continue the mission. We alternated going downstairs to the navigator station to cool off before going back on duty. About four hours after the second refueling, my window shattered. And the flight had to be continued without pressurization. Soon after that, the co-pilot began to experience severe stomach cramps. The navigator suffered intense pain in his knee. We decided to drop down to 12,000 feet. At this point, the flight was in the soup. Everybody was so worn out from fatigue that we all began making errors. The positive fix was difficult to obtain. Fuel consumption was high. So high that there was doubt as to whether we could make the next refueling point. Although there was an emergency in the making, we didn't declare it until a little too late. A strippler tanker was launched, but before contact could be made, we ran out of fuel. The bailout sequence began at 7,000 feet. Five ejected and three bailed out. The aircraft made one complete 360-degree left turn. And crashed into a clear, flat field at approximately a 45-degree angle. Fortunately, only two of the men received major injuries. Cause of the accident? Physiological breakdown as a result of heat, lack of pressurization, and fatigue. We are moving into new environments all the time. There's no way back. Man will never again be solely a ground animal. We're going deeper, higher, and faster, and there's no alternative. No and accept your physiological limits and stay alive. Thanks for watching!