Meteorological elements and their influence on human health

Meteorological (climatic) elements

temperature, humidity and precipitation, sunshine, wind velocity, air pressure.

Climate

The average weather, usually taken over a 30 year time period, for a particular region and time period.

It is the average pattern of weather for a particular region.

Earth has three climate zones: Polar, Temperate and Tropical.

Climate zones are further classified into ecosystems and biomes.

Weather

Weather consists of the short-term (minutes to about 15 days) variations of the atmosphere state.

Microclimate

Variations of the climate within a given area, usually influenced by hills, hollows, structures or proximity to bodies of water. A microclimate differs significantly from the general climate of a region.

Air temperature

(Also termed surface temperature in meteorology). The ambient temperature indicated by a thermometer exposed to the air but sheltered from direct solar radiation. The temperature is indicated by a thermometer placed in an instrument shelter 1.5 to two meters above ground. Thermometer is an instrument for measuring temperature.

Atmospheric pressure

Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of the air molecules above that surface.

Atmospheric pressure is measured with an instrument called a barometer.

Barograph is a recording barometer. Either daily or week barographs are used.

Atmospheric pressure

Humidity Water vapor content of the air (Some measure of

the water-content of air). Hygrometers and psychrometers are

instruments used for measuring the water vapor content in the air.

Absolute humidity (1) The ratio of the mass of water vapor to the

volume occupied by a mixture of water vapor and dry air.

(2) Mass of water contained in a unit volume of moist air.

Relative humidity

The (dimensionless) ratio of the actual vapor pressure of the air to the saturation vapor pressure. The relative humidity is usually expressed in per cent, and can be computed from psychrometric data.

Relative humidity

Relative humidity=(absolute humidity: maximum humidity)x 100%

Dew point (dew-point temperature) The temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur. When this temperature is below 0 °C, it is called the frost point.

In the dew point hygrometer a polished surface is reduced in temperature until the water vapour from the atmosphere forms on it. The temperature on this dew point enables the relative humidity of the atmsphere to be calculated.

The wet and dry bulb hygrometer

In this hygrometer , there are two thermometers mounted side by side, the bulb of one being surrounded by moistened muslin. The thermometer with the wet bulb will register a lower temperature than that with the dry bulb owing to the cooling effect of the evaporating water. The temperature difference enables the relative humidity to be calculated.

Saturation The condition in which the partial pressure of any fluid constituent (water in the atmospheric air) is equal to its maximum possible partial pressure under the existing environmental conditions, such that any increase in the amount of that constituent will initiate within it a change to a more condensed state. Evaporation ceases under such conditions.

Evaporation The physical process by which a liquid or solid substance is transformed to the gaseous state; the opposite of condensation. In meteorology, evaporation usually is restricted in use to the change of water from liquid to gas, while sublimation is used to the change from solid to gas as well as from gas to solid.

Insolation

Exposure of an object to the Sun. Intensity of incoming solar radiation

incident on a unit horizontal surface at a specific level.

Surface wind Wind blowing near the Earth's surface. Anemometer is an instrument which

measures wind speed or wind speed and direction.

Surface wind is measured, by convention, at a height of 10 m above ground in an area where the distance between the anemometer and any obstruction is at least 10 times the height of the obstruction.

Climate change

A study dealing with variations in climate on many different time scales from decades to millions of years, and the possible causes of such variations.

Global warming is shorthand for "climate change”. Climate scientists say the evidence is strong that humans are responsible for at least some of the warming since early in the 20th century.

Greenhouse effectThe sun supplies the energy that keeps the Earth warm enough for life. Once this energy reaches Earth, it follows complex paths. Some solar energy is reflected back into space, while the rest is absorbed by the atmosphere and the Earth's land and oceans. The absorbed energy warms the Earth, which in turn radiates heat back towards space as infrared energy. Water vapor, carbon dioxide and other greenhouse gases in the atmosphere absorb some of the outgoing infrared energy, which heats them. These molecules then radiate the energy in all directions, including back to Earth. In effect, some of the energy remains in our atmosphere, warming the planet. This process is often called the "greenhouse effect" .

Greenhouse gases

Carbon dioxide Water vapour Methane Oxides of nitrogen Ozone

temperature

T[C]=5(t[F]-32)

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Temperature regulation Humans and other mammals are homeothermic, able to maintain a relatively constant internal body temperature despite widely ranging environmental temperatures. Although the average human body temperature is 36.7 degrees Celsius (98.2 degrees Fahrenheit), this temperature varies depending on individual differences, time of day, the stage of sleep, and the ovulatory cycle in women. Thermoregulation is the balance between heat production mechanisms and heat loss mechanisms that occur to maintain a constant body temperature.

Temperature regulation mechanisms

Heat production mechanisms are:

metabolism, exercise, shivering.

Heat loss mechanisms divide into passive:

infrared radiation, conduction, convection

Active: evaporation.

Hypothermia

or low body temperature, is a result of prolonged exposure to cold. With a decrease in body temperature, all metabolic processes begin to slow. Hypothermia can be life-threatening.

Stages of Hypothermia in humans

Stage 1( mild hypothermia) - Body temperature drops 1-2 ° (1.8-3.6 °F, or between 99 - 95 degrees F - mild shivering occurs. One is unable to perform complex tasks with hands, shivering may be mild to severe, hands numb. Blood vessels in outer extremities contract, lessening heat loss to the outside air. Breathing becomes quick and shallow. Goose bumps form, to raise body hair on end in an attempt to create an insulating layer of air around the body.

Stages of Hypothermia in humans

Stage 2 - Body temperature drops 2-4 °C (3.6-7.2 °F, or between 95 - 90 degrees F) - Shivering becomes more violent. Muscle incoordination becomes apparent, movements slow and labored, stumbling pace, mild confusion, but may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm. Victim becomes pale. Lips, ears, fingers and toes may become blue.

Stages of Hypothermia in humans

Stage 3 (severe hypothermia)- Body temperature drops below approx 32.2 °C (90 °F). Violent shivering persists, difficulty speaking, sluggish thinking, amnesia starts to appear, unable to use hands, stumbling. Cellular metabolic processes shut down. Below 86 degrees F (28 C) shivering stops, exposed skin gets blue to puffy, muscle coordination is very poor, inability to walk appears, incoherent/irrational behavior turns into stupor, pulse and respiration rates are much decreased. Major organs fail. Clinical death occurs.

The donts in hypothermiaDo not rub or massage the casualty. Do not give alcohol.Do not give food or drink (this includes warm drinks, this is only in extreme cases). The reason being that blood is diverted from the major organs where it is needed, and is sent to the stomach and intestines to digest the food/liquid, therefore lowering the core temperature further.) Do not treat any frostbite.Do not allow the body to become vertical.

What you should do...

Call the emergency services. Get the patient to shelter. If possible, put the patient in a bath with

medium-temperature water, with the clothes on; do not do this to an elderly patient as death may occur as the blood flows to the surface of the skin restricting flow to the heart and brain.

What you should do...Place hot water bottles in the patient's armpits and between their legs. Monitor the patient and be prepared to give cardio-pulmonary resuscitation.Remove wet clothing if and only if a dry change is available.If in a wilderness environment, remove wet clothing from the victim and from one other person. Both individuals should get into the same sleeping bag if possible, or wrap in the same blanket, if the sleeping bag is too small.

Hospital treatment In a hospital, warming is accomplished by external techniques (blankets, warming devices) for mild hypothermia and by more invasive techniques such as warm intravenous fluids or even (washing) of the bladder, stomach, chest and abdominal cavities with warmed fluids for severely hypothermic patients. These patients are at high risk for arrythmias (irregular heartbeats), and care must be taken to minimize jostling and other disturbances until they have been sufficiently warmed, as these arrhythmias are very difficult to treat while the victim is still cold. An important tenet of treatment is that a person is not dead until he/she is warm and dead - remarkable stories of recovery after prolonged cardiac arrest have been reported in patients with hypothermia. This is presumably because the low temperature prevents some of the cellular damage that occurs when blood flow and oxygen are lost for an extended period of time.

Frostbite (congelatio) is the medical condition whereby damage is caused to skin and other tissues due to extreme cold. At or below 15°C (59° F), blood vessels close to the skin start to narrow (constrict). This helps to preserve core body temperature. In extreme cold or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of the body to dangerously low levels. The combination of cold temperature and poor blood flow can cause tissue injury. Frostbite is most likely to happen in body parts farthest from the heart, and those with a lot of surface area exposed to cold. These areas include the toes, fingers, ears and nose.

SymptomsGenerally, frostbite is accompanied with discoloration of the skin, along with burning and/or tingling sensations, partial or complete numbness, and possibly intense pain. If the nerves and blood vessels have been severely damaged, gangrene may follow, and amputation may eventually be required. If left untreated, frostbitten skin gradually darkens after a few hours. Skin destroyed by frostbite is completely black and looks loose and flayed, as if burnt.

TreatmentMove the victim to a warm, safe area. Wrap the affected areas with dressings and/or cloths. Do NOT rub or massage affected areas. Place the affected areas in warm (not hot) water, until the areas are soft and sensation has returned. Wrap the areas in clean, sterile dressings and attempt to reach medical help (if necessary). If has occurred, treat the hypothermia first.Medication: painkillers, anitibiotics, anti-tetanus vaccination.

Immersion foot/Trench foot Tissue damage to the foot caused by cold, damp conditions is called trench foot, immersion foot, chillblains or pernio. Damage occurs to soft tissue cell, blood vessels and nerves. Injury may be temporary or may result in permanent damage particularly to the nerves of the feet. Trench foot injuries are sustained in temperatures ranging from 32-65 degrees Fahrenheit. Trench foot differs from frostbite in that frostbite is the actual freezing of cells at or below 32 degrees Fahrenheit. Another difference between trench foot and frostbite is that frostbite can easily occur in the absence of moisture.

Symptoms

burning and tingling of the feet loss of sensation toes appear cyanotic (gray) and blotchy burning after rewarming maceration and fissures of the skin blisters, erythema (redness) peeling

skin

Warm water and tropical immersion foot

Occur with prolonged exposure to moisture in folks with excessive perspiration who work in enclosed rubber boots. Symptoms include painful thickening and maceration of the skin of the bottom of the foot. They are most common in adolescents and young adults. Quite often we'll see that a person's occupation contributes to warm water immersion foot. Workers who wear rubber boots and insulated boots, are most susceptible to trench foot and warm water immersion foot. The jungles of Vietnam and combat boots were a 'shoe in' for tropical immersion foot.

Treatment Limiting exposure to cold. Use in-shoe foot warmers or tropical L-arginine

cream. Maintain a dry envirinment inside the shoe. Rotate your shoes every other day to allow them to

dry thoroughly. Avoid synthetic materials like rubber or vinyl, wear

leather or cloth that can absorb moisture. Frequently change the socks to wick away moisture. Use talc or baby powder daily to wick away moisture. Hyperhydrosis (excessive perspiration) can be

treated with drying agents (aluminium chloride), formalin, antihistamine, injections of Botox).

Hyperthermia a body temperature that is higher than normal. One example of hyperthermia is fever. A fever is generally considered to be a body temperature over 38 degrees Celsius (100.4 degrees Fahrenheit). A fever is the body's natural defense to an infection by a bacterium or virus. Fevers are one of the body's mechanisms for eliminating an invading organism. Fevers may even make the immune system work more effectively. Heat exhaustion and heatstroke are other examples of hyperthermia. These occur when heat production exceeds the evaporative capabilities of the environment. Heatstroke may be fatal if untreated.

Heatstroke

occurs when the body fails to regulate its own temperature and body temperature continues to rise, often to 105° (40.6°) or higher.

Heatstroke is a medical emergency. Even with immediate treatment, it can be life-threatening or result in serious, long-term complications.

Symptoms

unconsciousness convulsions difficulty breathing rectal temperature over 104°F (40°C) confusion, restlessness, anxiety fast heart rate hot, dry skin (no sweating) vomiting or diarrhoea

First aid Move the person into a cool place. Remove the person's unnecessary clothing, and place the

person on his or her side to expose as much skin surface to the air as possible.

Cool the person's entire body by sponging or spraying cool—not cold—water, and fan the person to lower the body temperature. Apply ice packs to the groin, neck, and armpits, where large blood vessels lie close to the skin surface. Do not immerse the person in an ice bath. Check the person's rectal temperature frequently, and try to reduce it to 102.3° (39.1°). Do not give aspirin or acetaminophen. If the person is awake and alert enough to swallow, give the person fluids [32 -64 fl oz (1-2 L)] within the first 2 hours for hydration. However, a person with heatstroke may have an altered mental status and may not be able to safely drink fluids without help.

Sunstroke

Develops after prolonged exposure of an uncovered head to intense sun radiation. As a result the blood vessels inside the skull dilate thus pressing on the brain tissue.

The symptoms are like in heat stroke (headache, vomiting, unconsciousness).

First aid- remove the victim to a shelter protected from sunlight.

Heat exhaustion Heat exhaustion is one of the heat-related

syndromes, which range in severity from mild heat cramps to heat exhaustion to potentially life-threatening heatstroke.

Symptoms include: fainting, nausea, heavy sweating, rapid, weak heartbeat, low blood pressure, cool moist skin, low-grade fever.

Get the person out of the sun and into a shady or air-conditioned location.

Heat Cramps Heat cramps are muscle contractions,

usually in the muscles at the back of the calves. These contractions are forceful and painful.

These cramps seem to be connected to heat, dehydration, and poor conditioning, rather than to lack of salt or other mineral imbalances. They usually improve with rest, drinking water, and a cool environment.

Burns

1°burn- reddened, painful skin; leaves no scar, hair and glands will regrow

2°- painful; blisters filled with serum-like fluid form; leaves no scar, hair and glands will regrow

3°- tissues under the skin are burnt;it is anaesthetic as nerves are damaged; it heals leaving a scar

4°-tissues burn into an ash.

A-epidermis B-skin C-subcutaneous

tissue

Decompression sickness (DCS), the diver’s disease, the bends,

or caisson disease DCS is the name given to a variety of

symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. It is a type of diving hazard and dysbarism.

DCS is caused by inert gases (mainly nitrogen), normally dissolved in body fluids and tissues, to come out of physical solution and form gaseous bubbles.

Decompression sickness can happen in any of the following

situations: A diver ascends from a dive. An unpressurized aircraft flies upwards. The cabin pressurization system of an aircraft fails. Divers flying in any aircraft shortly after diving. Pressurized

aircraft are not risk-free, since the cabin pressure is not maintained at sea-level pressure.

A worker comes out of a pressurized caisson, or out of a mine, which has been pressurized to keep water out.

An astronaut exits a space vehicle to perform an extra-vehicular activity because the pressure in the space suit is lower than the pressure in the vehicle.

Predisposing factors Magnitude of the pressure reduction: A large pressure reduction is more

likely to cause DCS than a small one. Repetitive Exposures: Repetitive dives or ascents to altitudes above

18,000 feet within a short period of time (a few hours). Rate of Ascent: The faster the rate of ascent to altitude, the greater the

risk of developing altitude DCS. Time at Altitude: The longer the duration of the flight to altitudes of 18,000

feet and above, the greater the risk of altitude DCS. Age: There are some reports indicating a higher risk of altitude DCS with

increasing age. Previous Injury: There is some indication that recent joint or limb injuries

may predispose individuals to developing "the bends." Very cold ambient temperatures may increase the risk of altitude DCS. High body fat content increases the risk of altitude DCS. The after-effects of alcohol consumption increase the susceptibility to

DCS. Patent foramen ovale in the heart.

Signs and symptoms Bubbles can form anywhere in the body, but symptomatic

sensation is most frequently observed in the shoulders, elbows, knees, and ankles.

"The bends" (joint pain) accounts for about 60 to 70% of all altitude DCS cases, with the shoulder being the most common site. These types are classifed medically as DCS I.

Neurological symptoms are present in 10% to 15% of all DCS cases with headache and visual disturbances the most common. DCS cases with neurological symptoms are generally classified as DCS II.

"The chokes” (shortness of breath, cough) are rare and occur in less than 2% of all DCS cases.

Skin manifestations are present in about 10 to 15% of all DCS cases.

This rash appeared 9 hours after a scuba dive. What is the diagnosis?

1. Decompression sickness2. Jellyfish envenomation3. Mycobacterium marinum infection4. Phylum Porifera contact dermatitis5. Scombroid fish poisoning

Answer

Decompression sickness

Cutis marmorata is a dermal manifestation of decompression sickness. Initially, there is erythema accompanied by pruritus, and then the rash spreads irregularly and deepens in color. It develops a mottled appearance, with areas of pallor surrounded by cyanotic patches. During recompression, the rash resolves.

Treatment

Recompression is the only effective treatment for severe DCS, although rest and oxygen (increasing the percentage of oxygen in the air being breathed via a tight fitting oxygen mask) applied to lighter cases can be effective. Recompression is normally carried out in a recompression chamber. In diving, a high-risk alternative is in-water recompression.

High-Altitude Sickness Lack of oxygen causes high-altitude

sickness. As altitude increases, the air becomes "thinner," which means less oxygen is in the atmosphere. You get less oxygen in your lungs with each breath, so the amount of oxygen in your blood declines. (This is called hypoxia). All people can experience mountain sickness, but it may be more severe in people who have heart or lung problems.

Symptoms Symptoms usually begin within 48 hours of arriving at high

altitude. The higher the altitude, the greater the effects. People can notice effects when they go to an altitude of 7,000 to 8,000 feet. If you have heart disease (such as heart failure) or lung disease (such as emphysema), you may have symptoms at lower altitudes. Symptoms include:

headaches, breathlessness, fatigue

nausea or vomiting inability to sleep swelling of the face, hands and feet. At very high altitudes, body fluid can leak into the brain

(called brain edema) or into the lungs (pulmonary edema). Both these conditions can be serious or even life-threatening.

Avoidance Increase altitude slowly. Climbers and hikers can take two

days to reach 8,000 feet, and then another day for each 1,000 to 2,000 higher feet. Most people can adjust or "acclimatize" to the high altitude within a few days. Here are some tips:

Avoid strenuous activity for the first day or two.

Drink extra fluid. Be careful of drinking alcohol.  Its effect is magnified at high

altitude. Your doctor may prescribe medication to help prevent or

treat altitude sickness. If you have a heart or lung condition, consult your physician

before going to high altitude. He or she can tell you whether your condition will let your body adjust to the lower oxygen in the atmosphere.

Thank you for your attention!