4. 1. Life giving oxygen
2. Body cooling
3. Transmits stimuli of smell and hearing
4. Disease causation- by agents/ pollutants
Human beings need a continuous supply of 10-20 m3/day air
Functions of Air
4
5. Composition of Air
N2= 78.1%
O2= 20.9%
Argon
Neon
Krypton
Xenon
Helium
Water vapour
Ammonia
Dust
Bacteria
Spores
Veg.debris
CO2= 0.03%
5
6. What makes air impure?
1. Respiration of human beings & animals
2. Combustion of coal, gas, oil, etc.
3. Decomposition of organic matter
4. Trade, traffic and manufacturing processes-dust, fumes, vapors and gases
6
7. Self-cleansing mechanisms
1. Wind: sweeps away the impurities by its movement
2. Sunlight: oxidizing & killing bacteria
3. Rain: cleanses the atmosphere by removing the
suspended & gaseous impurities
4. Plant life: utilize CO2 & generate oxygen
7
8. Air changes of occupied room
• Chemical changes: CO2 O2
• Physical changes
1. Rise in temperature
2. Increase of humidity
3. Decrease in air movement
4. Body odours
5. Bacterial pollution
8
Comfort, health and
efficiency
• Feeling of suffocation/
discomfort
• Headache, drowsiness
• Inability to concentrate
• Risk of droplet infection
Resistance to disease
9. Discomfort
1. Subjective feeling or sensation in ill ventilated and over-crowded place
2. Leads to heat retention
3. Problems of ventilation are physical not chemical, cutaneous not respiratory
9
10. Comfort
1. Complex subjective experience, depends on physical, physiological, and
psychological factors, difficult to determine
2. Comfortable thermal conditions --“a person can maintain normal balance in
production & loss of heat at normal body temperature & without sweating”
3. It’s the range of effective temperatures over which the majority of adults feel
comfortable
10
11. Indices of thermal comfort
1. Air temperature
2. Air temperature + Humidity
3. Cooling power-Air temp.+ Humidity+ Air movement
(measured by Kata thermometer, devised by Hill)
11
12. 4. Effective temperature-combines temp.,
humidity & movement of internal air (obtained by
special charts)
5. Corrected effective temperature (CET)-
includes radiant heat along Effective temperature
& also uses Globe thermometer
12
Indices of thermal comfort
13. McArdle’s maximum allowable sweat rate- P4SR
Predicted four-hour sweat rate can be obtained from any combination
of dry and wet bulb temperature of the air, mean radiant air
temperature and air velocity, under different work intensity
• Comfort zone: 1-3 litre
• Just tolerable: 3-4.5 litre
• Intolerable: 4.5+ litre
13
15. Air pollution
The presence of substances (gases &
particulate matter) generated by the
activity of man in concentrations that
interfere with human health, safety or
comfort
15
16. Sources of air pollution
1. Automobile
2. Industries
3. Domestic
4. Miscellaneous
16
17. Automobiles
• Major source of air pollution through out urban areas, they include
1. Carbon monoxide
2. Lead
3. Nitrogen oxides
4. Particulate matter
17
19. Domestic
• Domestic combustion of coal, wood
or oil is a major source of smoke,
dust, SO2, N02
• The most direct & important source
of air pollution affecting the health
of many people is tobacco smoke
19
24. Monitoring of air pollution
Indicators of air pollution
1. Sulphur dioxide
2. Smoke or soiling index
3. Grit & dust measurement
4. Coefficient of haze
5. Suspended particulate matter (SPM)
6. Air pollution index
25
25. Effects of air pollution
Health aspects:
1. respiratory and cardio respiratory systems
2. the elderly, children, smokers & those with chronic respiratory difficulties
are most vulnerable
Social aspects:
1. destruction of plant & animal life
2. corrosion of metals
3. damage to buildings
4. cost of cleaning & maintenance & repairs
5. soiling of clothing
26
26. Air pollution monitoring-India
• Central pollution control board sponsors “the national air quality
monitoring programme” in India
• database generated over last 14 years in 10 major Indian cities
• evaluation of long-term air quality trends for health related criteria
pollutants
27
27. • Suspended particulate matter
exceeds the CPCB standards
in all cities
• Respirable suspended
particulate matter is higher at
industrial areas
• Acid rain in urban areas of
India
28
32. Prevention & control
1. Containment
2. Replacement
3. Dilution
4. Legislation
5. International action
6. Disinfection
33
33. Containment
• Prevention of escape of toxic substances
into ambient air by a variety of
engineering measures such as
1. Enclosure
2. Ventilation
3. Air cleaning
4. Arresters
34
34. Replacement
• Replacing a technological process
causing air pollution by a new process
1. Use of electricity, natural gas & central heating in place of coal
2. Reduce lead in petrol which is cumulative poison
35
36. Legislation
To decrease the nuisance of air pollution,
the Govt. of India have enacted
“The Air (Prevention and Control of Pollution) Act” in 1981
37
37. International action
• By WHO -international network of laboratories for
monitoring, study and issuing warnings of air pollution
1. two international centers at London & Washington
2. three centres at Moscow, Nagpur & Tokyo
3. 20 laboratories in various parts
38
38. Disinfection of air
• It is still in the experimental stage and the methods employed are
1. Mechanical ventilation
2. Ultraviolet radiation
3. Chemical mists
4. Dust control
39
40. Introduction
• replacement of vitiated air by a supply of fresh outdoor air
• control of quality of incoming air with regard to its temperature,
humidity & purity
• To provide a thermal environment that is comfortable & free from
risk of infection
41
41. Standards of ventilation
• Adequate or inadequate
a. 1/5th of floor space- Windows
b. 2/5th of floor space- Doors + windows
• The fixing of standards is difficult and is based to a large extent on the efficiency
of ventilation in removing body odour
a. Cubic space: 300-3000 c.ft
b. Air change: 2-3 changes in living room & 4-6 changes in work room or
assemblies
c. Floor space: more important than cubic space & optimum requirement per
person vary from 50-100 sft. 42
43. Natural ventilation
• Reliance is placed on certain forces which operate in nature
1. The wind: perflation, aspiration, cross ventilation
2. Diffusion
3. Inequality of temperature
#chief draw back – cant regulate the velocity
of the incoming air nor to adjust its
temperature or humidity
44. Exhaust ventilation
• Air is extracted or exhausted to the outside by exhaust fans
• Exhausting of air creates vacuum
• Used in -
1. Large halls and auditoriums
2. Industries to remove contaminants at their source
45
45. Plenum ventilation
• fresh air is blown into the room by centrifugal fans to create a positive
pressure and displace the vitiated air
46
46. Balanced ventilation
• This is a combination of the exhaust and plenum systems of ventilation
• The blowing fan must balance the exhaust fan
47
47. Air conditioning
• simultaneous control factors affecting
both the physical and chemical conditions
of the atmosphere within any confined
space or room
• include temperature, humidity, air movement, distribution,
dust, bacteria, odours & toxic gases 48
Dry kata- 6 and above, wet kata- 20 and above- thermal comfort
Smoke + fog= smog (less vertical air movt in winter months. So increased pollution)
4 main reasons? measures taken? Finally what made it subside
CO= by incomplete combustion of carbon , Benzo pyrene (BaP) most dangerous PAH
There are six AQI categories, namely Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe. The proposed AQI will consider eight pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb) for which short-term (up to 24-hourly averaging period) National Ambient Air Quality Standards are prescribed
Height of chimneys, local investigations, research and education, smokeless zones and standards for ambient air quality