1. CLIMATE
 DEFINITION:
“The sum total of all the meteorological conditions
in reaction to animal and plant life”
In other words Climate is the average condition
of the atmosphere
• WHEATHER : denotes a single event in a series
of conditions, which make up the climate

2. Climate is composed of
 VARIABLE FACTORS:
1. Freshness of air
2. Freedom from dust and smoke
3. Movement of the air
4. Rain fall
5. Humidity
6. Sunlight
7. Cloudiness
8. Fog
9. Temperature
10. Barometric Pressure
11. Wind velocity

3. Climatic Zones
 The world has been divided into different
climatic zones
 Each zone has its advantage and disadvantages
but the people of that zone get acclimatized to
overcome the difficulties
 Factors Favouring development of insects:
1. High temperature
2. Humidity
3. Rainfall

4. Climate and Disease
 Dry Deserts favour the growth of :
1. Rodents e.g. Rats
2. Flea
3. Ticks
Responsible for diseases like Plague and Tick
fever etc.
• Cold climates………Typhus
• Heat & moisture favours growth of insects
leading to
 Sand Fly fever, Malaria, Filariasis, Dengue fever

5. Contnd……
 MALNUTRITION: specially Vit. B.
deficiency in Tropics
 SEASONS & DISEASES :
• Pollination in spring….Hay Fever, Asthma
• Malaria………………..Rainy season
• Cerebro-spinal fever…..Winter( due to
close contact)

6. Effects of Climate on Health
 TEMPERATURE :
1. Direct heat leads to……..Sun stroke
2. Indirect heat my lead to…
 Syncope
 Anxiety
 Liver disorders
 Bowl disorders
 Changes in Metabolism

7. Contnd……
 HOT & MOIST CLIMATE Leads to……
• Debilitating & enervating effects
• Mental strain
• Humidity & moisture…..the sense of freshness
depends upon air movement
• Moist Climates are less healthy than dry ones
• Heat & moisture leads to growth of micro-
organisms responsible for diseases like,
(a). Cholera (b). Plague (c). Pulmonary T.B.
• Dry air leads to Eruptive lesions

8. Atmospheric Pressure
 THE HIGHEST ALTITUDE :
 at which man can live and work is between 17000
to 18000 ft.
 Un-acclimatized man can survive only for a few
minutes at 25000 ft.
 But there is a record of living for 19 days at this
height by the members of expeditions
 300 ft. under water man can work only for a small
period

9. Contnd……
 All air crafts maintain the cabin pressure to
sea level
 At sea level : 760 mm. / Hg. or 15 lbs. / sq.
Inch
 At higher altitude it falls
 Under water rise of 760 mm. / Hg. For each
33 ft.

10. Effects on Human Body
 Body tissues
 Composed chiefly of water
 Non compressible
 Transmission of pressure to internal tissue is
tolerable
• If there is a pressure difference such as the cavities
containing air e.g. middle ear
 During ascent ----------------------------Barotrauma
 During descent-------in mine workers, Congestion,
Oedema & hemorrhage in lungs

11. Effects of Low Pressure
 An ascent of 1800 ft…..Pressure falls by 1 lbs. /
sq. inch
 An ascent of 300 ft…….Temp. falls by 1 F
MOUNTAIN SICKNESS OR AVIATORS
SICKNESS :
 The condition is due to low pressure, low Oxygen
concentration
 Sudden exposure to 13000 ft….Mountain sickness

12. Contnd……
 There could be two types of presentations:
A. Acute mountain sickness :
 Fatigue
 Irritability
 Headache
 Insomnia
 Bleeding nose
 Ringing ears
 vomiting

13. Contnd……
B. High altitude Pulmonary oedema :
Symptoms appear at the third day
 Cough
 C / S Breathing
 Coma leading to death
 But if the changes are slow the body adapts even
at 15,000-20,000 ft.
 Compensatory Polycythemia is there due to
raised Hb.%

14. Effects of High Pressure
 Isfaced by (workers):
 Divers
 Compressed air shafts
 Mines
 Caissons
 Under water construction

15. Contnd…..
 CAISSONS DISEASE :
 In the Caissons the pressure is rarely 30-35 lbs.
 The divers go as low as 20 Fathoms where the
pressure is 53 lbs.
 Due to the high pressure, the blood present in the
lungs get saturated with air
 During decompression the blood gives up
Nitrogen to the alveolar air
 Oxygen is retained in the tissues & Nitrogen is
liberated causing bubbles………Air Emboli

16. Contnd……
 When the pressure is > 3 atmospheres :
 Working should not be > 1 hour
 Sudden decompression (Bends & Screws)
 Workers or divers should come up slowly
(Haldane’s Method of gradual decompression) to
avoid “Air Embolism”
 Symptoms of exposure to high pressure:
 Euphoria, Sensation of heat, Deep & fast
respiration, Bradycardia, Disturbance of hearing,
Hemorrhages-----of mouth, lungs and tympanic
cavity