7. EFFECTS OF ATMOSPHERIC
PRESSURE ON HEALTH
1.HIGH ALTITUDES-
• AIR DENSITY
• PARTIAL PRESSURE OF O2
• SURVIVAL
PHYSIOLOGICAL EFFECTS:
1.INCREASE IN RESPIRATION
2.INCREASE IN CONCENTRATION OF HB
3.INCREASE IN CARDIAC OUTPUT
8. EFFECTS OF ATMOSPHERIC
PRESSURE ON HEALTH
1. HIGHER ALTITUDES
• A. ACUTE MOUNTAIN SICKNESS
• B. HIGH ALTITUDE PULMONARY OEDEMA
2. LOWER ALTITUDES-
GASES O2, CO2 AND N2
EXCESS OF EACH
AIR EMBOLISM
CAISSON’S DISEASE
9. AIR TEMPERATURE
• FACTORS INFLUENCING:
1. LATITUDE
2. ALTITUDE
3. DIRECTION OF WIND
4. PROXIMITY TO SEA
10. AIR TEMPERATURE
• MEASUREMENT:
1. MERCURY THERMOMETER- WIDELY USED
2. ALCOHOL THERMOMETER
ESSENTIAL CONDITIONS-
1. FREE ACCESS OF AIR TO BULBS
2. PROTECTION AGAINST RADIANT HEAT
STEVENSON SCREEN-SPECIAL APPROVED SCREEN
11. AIR TEMPERATURE
1. DRY BULB THERMOMETER
2. WET BULB THERMOMETER
3. MAXIMUM THERMOMETER
4. MINIMUM THERMOMETER
5. SIX’S MAXIMUM AND MINIMUM
THERMOMETER
6. GLOBE THERMOMETER
7. WET GLOBE THERMOMETER
8. SILVERED THERMOMETER
12. AIR TEMPERATURE
9. KATA THERMOMETER: ALCOHOL THERMOMETER
WET KATA
DRY KATA
METHOD OF USE
COOLING POWER OF AIR
KATA FACTOR
THERMAL COMFORT
13. AIR TEMPERATURE
• TYPES:
• 1.STANDARD KATA- 100 DEG F- 95 DEG F- RED
• 2.HIGH TEMP. KATA- 130 DEG F- 125 DEG F-DARK BLUE
• 3.EXTRA HIGH TEMP. KATA- 150 DEG F- 145 DEG F-
MAGENTA
NOT USED IN TROPICAL COUNTRIES AS TEMP. ABOVE
100 DEG F
17. HEAT STRESS INDICES
• DEF- BURDEN/LOAD OF HEAT THAT MUST BE
DISSIPATED IF THE BODY IS TO REMAIN IN
THERMAL EQUILIBRIUM
• FACTORS INFLUENCING:
1. METABOLIC RATE
2. AIR TEMPERATURE
3. HUMIDITY
4. AIR MOVEMENT
5. RADIANT TEMPERATURE
18. HEAT STRESS INDICES
• MANY DEVISED, BUT NONE VALID
1. EQUATORIAL INDEX- THIS DENOTES THE
TEMPERATURE OF STILL AND
SATURATED AIR WHICH IS EQUIVALENT
PHYSIOLOGICALLY TO THE CLIMATE
UNDER CONSIDERATION.
19. HEAT STRESS INDICES
• 2. HEAT STRESS INDEX- THIS TAKES INTO CONSIDERATION
THE METABOLIC RATE AND THE PRINCIPAL CHANNELS OF
HEAT EXCHANGE BETWEEN THE HUMAN BODY AND THE
ENVIRONMENT.
• THE HEAT STRESS INDEX REPRESENTS THE PERCENTAGE
OF THE HEAT STORAGE CAPACITY OF AN AVERAGE MAN.
NOMOGRAMS HAVE BEEN PROVIDED FROM WHICH THE
VALUE OF THE HEAT STRESS INDEX COULD BE EASILY
CALCULATED.
20. HEAT STRESS INDICES
• 3. PREDICTED FOUR HOUR SWEAT RATE:
• THE RATE AT WHICH A MAN SWEATS IS A GOOD INDEX OF
THE HEAT STRESS TO WHICH HE IS SUBJECTED. A SWEAT
RATE OF 4.5 LITRES IN 4 HOURS IS THE UPPER LIMIT OF
TOLERANCE IN HEALTH FOR WORK IN HOT ENVIRONMENT.
A SWEAT RATE OF 2.5 LITRES IN 4 HOURS IS CONSIDERED
OPTIMAL FOR A WORKING MAN. P4SR IS APPLICABLE ONLY
IN THE SITUATION WHERE SWEATING OCCURS.
23. EFFECT OF COLD STRESS
1. GENERAL-NUMBNESS, LOSS OF SENSATION,
MUSCULAR WEAKNESS, DESIRE FOR SLEEP, COMA
AND DEATH
2. LOCAL- IMMERSION/TRENCH FOOT, FROST BITE
TREATMENT- PROPER DRESS, WARMING AFFECTED
PART AT 44 DEG C FOR 20 MIN
24. GLOBAL WARMING
• EMISSION OF GREEN HOUSE GASES
• CO2 MAJOR COMPONENT
• EFFECT
• OVERWHELM CAPACITY TO ADAPT
• CHANGES IN CONFIGURATION
• TEMPERATE ZONE WARMING
• HEAT ISLAND PHENOMENON
25. HUMIDITY
• DEW POINT
1. ABSOLUTE HUMIDITY
2. RELATIVE HUMIDITY- RH EXCEEDS 65%-
AIR STICKY AND UNCOMFORTABLE, BELOW
30% UNPLEASANT
33. CLOUDS AND WEATHER
OBSERVATION
• METEOROLOGICAL SATELLITES- AUTOMATIC
PICTURES
• MEASURE TEMPERATURE, HUMIDITY AND
GIVE IDEA OF CLOUDS
34. PRACTICAL APPLICATION
• DEFENSE FORCE
• HOUSING & CONSTRUCTION
• TRAVEL MEDICINE
• OCCUPATIONAL MEDICINE
• GEOGRAPHICAL INFORMATION SYSTEM
Editor's Notes
1 Acute Moutain Sickness: Relatively common, harmless and transient condition characterized by headache, insomnia, breathlessness, nausea, vomiting and impaired vision
Symptoms inconclusively proved- hypoxia/intricate hormonal & biochemical?
2.High Altitude Pulmonary Oedema- Symptoms appear on 3rd day and indistinguishable from those of acute mountain sickness
Symptoms- cough, irregular or Cheyne-Stokes breathing, oliguria, mental confusion and hallucination, stupor, seizure and coma
Rare below 12,000 feet
Does not respond to antibiotics
Treatment- carried to lower altitudes as soon as possible
Globe thermometer
Structure-
It registers a higher temperature than the ordinary air temperature thermometer because it is affected by both air temperature and radiant heat.
Radiant heat measure –difference between globe thermometer temperature and that of ordinary dry bulb
Influenced by air velocity
