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AIR HYGIENE.PPTX
- 1. UNIVERSITATEA DE STAT DE MEDICINA SI FARMACIE NICOLAE TESTEMITANU BIVOL NATALIA
- 2. LIST OF CONTENTS 1) ATMOSPHERIC AIR 2) PRINCIPAL LAYERS 3) ATMOSPHERE GASES 4) TROPOSPHERE 5) STRATOSPHERE 6) MESOSPHERE 7) THERMOSPHERE (IONOSPHERE AND EXOSPHERE) 8) COMPOSITION OF AIR 9) CHEMICAL COMPOSITION OF AIR 10) OXYGEN 11) CARBON DIOXIDE
- 3. ATMOSPHERIC AIR The atmosphere of Earth is the layer of gases, commonly known as air that surrounds the planet Earth and is retained by Earth gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variations). By volume, dry air contains 78.09% of nitrogen, 20.95% of oxygen, 0.93% of argon, 0.039% of carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air content and atmospheric pressure vary at different layers, and air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in the Earth's troposphere and in artificial atmospheres.
- 4. PRINCIPAL LAYERS In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions. Because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. 6 In this way, Earth atmosphere can be divided (it is called atmospheric stratification) into five main layers. Excluding the exosphere, Earth has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. From the highest to the lowest, the five main layers are: • Exosphere: 700 to 10,000 km (440 to 6,200 miles) • Thermosphere: 80 to 700 km (50 to 440 miles) • Mesosphere: 50 to 80 km (31 to 50 miles) • Stratosphere: 12 to 50 km (7 to 31 miles) • Troposphere: 0 to 18 km (0 to 7 miles)
- 6. ATMOSPHERE GASES The concentration of atmosphere gases varies depending on the atmosphere layers. The troposphere contains primarily nitrogen (78%) and oxygen (21%). The remaining 1% of the atmosphere is trace gases. The stratosphere contains a layer of relatively high concentrations of 7 ozone. The lower part of the thermosphere is the ionosphere. This layer has free ions and electrons that are the result of ionization of gas molecules. As the distance increases from Earth the atmosphere becomes thinner as the molecules move further and further apart.
- 7. TROPOSPHERE The lower boundary is the surface of the Earth. The upper boundary varies between 7 km (23,000 ft.) above the poles and 14 km (56.000 ft.) above the equator. This is the layer of the atmosphere where we live. The troposphere contains 75% of the total mass of the atmosphere. The air cools 6.5°C for each kilometer above sea level. Most of the energy from the sun travels through the atmosphere and is absorbed by the ground. The ground heats up warming the air above creating air currents. The rising of warm air and falling of cooler air creates convection currents that cause air circulation in this layer of the atmosphere
- 8. STRATOSPHERE The lower boundary is the tropopause which separates the stratosphere from the troposphere. The upper boundary of the stratosphere is 50 km (32 miles; 170,000 feet). The bottom layer of the stratosphere remains constantly at approximately 60°C. Jet streams are formed here as cold air from the poles meets the warmer air rising from the equator. It is a strong eastward moving wind that blows horizontally around the Earth. The stratosphere contains the ozone layer. Ozone is created when radiation from the sun splits two-atom oxygen molecules into separate atoms. They combine with other two-atom molecules to form a three atom molecule. The layer acts as a shield from ultraviolet radiation from the sun. The upper part of the stratosphere warms up to approximately 18°C as the ozone reacts with ultraviolet radiation giving off enough heat to warm this layer.
- 9. MESOSPHERE The mesosphere is the third layer of the atmosphere. It extends from the top of the stratopause to an altitude between 80 and 85 km. The temperature begins to drop in this layer until it reaches minus 90°C. The upper region of the mesosphere is the coldest region of the Earths atmosphere layers. Water vapor is sometimes present in this layer and it can be seen from Earth as thin feathery clouds of ice crystals. Many meteors entering the atmosphere burn up in this layer. The heat causes 8 enough friction between a meteoroid and gas particles in the mesosphere to burn them up. Shooting stars are the trail of hot glowing gases as a meteoroid burns
- 10. THERMOSPHERE (IONOSPHERE AND EXOSPHERE) Location of layer above Earth: 640 kilometers (400 miles; 2.100.000 feet).The thermosphere has two layers of Earths atmosphere layers. The atmosphere is very thin in the thermosphere. The space shuttles orbit in the thermosphere. The layer has free ions and electrons that are the result of ionization of gas particles. Radio waves bounce off the ionosphere allowing communication with countries overseas. The aurora borealis, (northern lights) is formed when electrically charged particles from the sun collide with particles in the ionosphere producing multicolored lights. The temperature in this region can reach 1500°C (2.730 degrees F). The air particles are so far apart that a person would not feel warmth because of the low density of the particles. The exosphere is the highest layer of the atmosphere. It extends up to 10.000 km (6.200 miles; 33.000.000 feet.) above the Earth. Satellites orbit the Earth in the exosphere. The atmosphere in this layer is extremely thin and atoms and molecules of air are constantly escaping into the outer space. Free-moving particles move in and out of the solar wind in the exosphere
- 12. COMPOSITION OF AIR Air contains different gases such as nitrogen, oxygen, carbon dioxide and other gases (It includes water vapour, trace gases like argon and helium, hydrogen, smoke and dust particles, etc.) The below diagram gives an idea about the main components of air. The composition of air varies from place to place. For example, the air is thinner on mountains as compared to plains. This is the reason why mountaineers always carry oxygen cylinders with them. Also, the percentage of oxygen in the air may be higher in areas where there is more greenery. In the desert areas, the water vapour content will be significantly lower than the regular areas because of the lack of water in desert areas.
- 13. CHEMICAL COMPOSITION OF AIR NITROGEN It is the major component found in the air. It is the most abundant gas on the earth’s planet too. It is required by plants and animals for their growth. The circulation of nitrogen between these organisms and the atmosphere is called the nitrogen cycle. The nitrogen cycle is essential for maintaining productive and healthy ecosystems. Nitrogen present in the air is also used to manufacture fertilisers which helps in the healthy growth of plants.
- 14. OXYGEN Air contains around 21% of oxygen. It is called the life-supporting gas. Oxygen is necessary for all living organisms because they derive energy from food with the help of oxygen. Respiration is the process of taking in oxygen, using it to make energy (by breaking down food), and then exhaling carbon dioxide. Besides breathing, the presence of oxygen is required for combustion (that is, burning of fuels and other substances). Both respiration and combustion processes utilise oxygen and release carbon dioxide in the atmosphere.
- 15. CARBON DIOXIDE Carbon dioxide makes up a small component of the air around us. It is an important gas for plants as well as animals. Plants use carbon dioxide for making food during the process of photosynthesis. Carbon dioxide is known as a greenhouse gas as it helps to trap heat. The property of trapping heat on the earth’s atmosphere and thus maintaining a comfortably warm temperature is known as the greenhouse effect. The percentage of carbon dioxide in the atmosphere keeps on changing from one place to another. It will be more in polluted areas.
- 16. MEDICAL IMPORTANCE OF AIR HYGIENE It has thermolytic influence. It has unfavorable effects when it drops below some limits, which are considered to be physiological, or when it exceeds some superior limits. It influences air pollution. It influences the other physical air factors (humidity, air currents, pressure).