AIR POLLUTION

INTRODUCTION

• Air constitutes the immediate physical environment. It is such an important environment that without air, life wouldnot have existed on earth. The public health importance of air is that not only it is necessary for breathing purposes, coolingof the body, hearing and smelling but also it acts as a vehicle of transmission of diseases, resulting in even epidemics and pandemics.

• Air is a mixture of gasses, mainly nitrogen (78%), oxygen (21%) and carbon dioxide (0.03%), remaining by other gassessuch as argon, neon, helium, xenon, etc. Strictly speaking there is no pure air. Air always contains foreign substances inthe form of solid, liquid (moisture) and gases, at all times, in all places. Air is said to have become polluted when itcontains these foreign substances such as dust, becteriae, spores gases etc in excessive concentration, so as to affectthe health of human beings and animals and causes damage to plants and properties.

CHANGES IN THE AIR DUE TO HUMAN OCCUPANCY

• Due to human occupancy, the air in the room is vitiated. The changes that take place in the air of such an occupied room are physical and chemical.
• The physical changes are:

i. Rise in the temperature due to emanation of body heat.

ii. Rise in the relative humidity due to expiration and

perspiration

• iii. Decrease in the air

movement.

• iv. Occurrence of

unpleasant odors arising

from expiration,

perspiration, bad oral

hygiene, dirty clothes and

other sources.

• v. Bacterial pollution by the infected droplets.

• The chemical changes are: —

i. Increase in the CO2

concentration

ii. Decrease in the 02

concentration. The

vitiation of air affects

the health, comfort and

efficiency of occupants

mainly due to physical

changes in the air.

Effects of Vitiated Air

• They are divided into acute and

chronic.

• Acute effects are lassitude, head ache, nausea, vertigo, vomiting and even collapse.
• Death may occur in extreme cases.

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• Chronic effects are anemia, debility, digestive disturbances, nutritional and metabolic disorders, lowered vitality anddecreased resistance to infections.
• The working efficiency is decreased and the output of the work falls.The effects of vitiation of air was first observed by Sir Leonard Hill.

INDICATORS OF THERMAL COMFORT

• 1. Air Temperature
• 2. Air Temperature and Humidity

This is a better indicator than air temperature alone

but still this is unsatisfactory.

• 3. Air Temperature, Humidity and Air Movement

These three together is called 'Cooling power' of the

air, which can be measured by a device called ‘Kata

thermometer'. A dry kata reading of 6 and above and

a wet kata reading of 20 and above are regarded as an

index of thermal comfort.

4. EFFECTIVE TEMPERATURE

• Effective temperature (ET) is the combined effect of air temperature, humidity and air movement (cooling power) on the sensation of warmth or cold felt by the human body. But this does not include the effect of radiation from the surrounding structures.

COMFORT ZONE

• It is the range of corrected effective temperature in which the individual or the worker in an industry, feels comfortable. Thecriterae of comfort zone are:
• Corrected effective temperature-25 to 27°C (77-80°F)
• Relative Humidity-30 to 65 percent
• Dry kata-6 and above
• Wet kata-20 and above
• Predicted four hour sweat rate (P4SR) - 1 to 3 liters P4SR is applicable only in that situation where sweating occurs.

AIR POLLUTION

AIR POLLUTION

• Air pollution is a constant and menacing problem throughoutthe world, due to man's own activities like industrializationand urbanization.
• It is increasing progressively during the past few decades.
• Air pollution is not only a public health problem but also an economic problem.
• Air Pollutants

These may be chemical or biological.

CHEMICAL POLLUTANTS

• These may be particulate matters, gasses or metals.
• Particulate matters: Dust, smoke, soot, sand, grit.
• Gasses: CO, CO2, H2,S, CH4, NO2, SO2, MIC (methyl iso-cyanide), fluorohydrocarbons, etc.
• Metals:Arsenic, berrylium, copper, zinc, lead, carcinogens,etc.

BIOLOGICAL POLLUTANTS

• Pathogens (microbes), spores, etc.
• Although the Earth's atmosphere extends to several kms above the surface, it is only the first 30 kms that hold the major portion of the atmospheric gasses. Man is concerned only with the first 8 to 10 kms of the atmosphere.
• Degree of air pollution is influenced by topography, i.e. atmospheric temperature, humidity, atmospheric pressure and air movement.
• Pollutants are affected by sunlight and temperature inversion.

SOURCES OF AIR POLLUTION

• Domestic sources: Burning of fire wood, kerosene oil, coal,etc.
• Industrial sources. Factories of iron and steel, paper, cement, fertilizers, thermal power plant, petroleum refineries, etc.

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• Vehicular sources: Motor vehicles, railways, ships, aero-planes, etc.
• Miscellaneous: Tobacco smoking, nuclear explosions, forest-fires, volcanoes, burning of refuse, dust-storm, ocean spray, etc.

Effects on human health

EFFECTS ON PLANTS

MONITORING OF AIR POLLUTION

• The indicators of air pollution are-
• (1) Sulphur dioxide- 500 ug/m' for 10 minutes or 350ug/m² for 1hour is considered as air pollution.
• (2) Smoke or soiling index-Smoke concentration in micrograms/cubic metre of air.
• (3) Grit and dust measurement.
• (4) Air pollution index- 10 x SO2 concentration (in ppm) + 2 x CO concentration (in ppm) + 2 x cofficient of haze.

when this value exceed 12-50 or more, it is alarming.

1. Containment—It is prevention of escape of toxic substances in air by engineering methods, such as enclosure, ventilation, and air cleaning.

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(2) Replacement- Technical replacement of a process to

reduce pollution e.g., to increase the use of electricity

and natural gas inplace of coal burning.

• (3) Dilution, To increase the selfcleaning capacity of environmentby establishment of green belt between industrial and residentialareas.

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• (4) Legislation- It includes height of chimneys, creation ofsmokeless zones and research concerning air pollution.

DISINFECTION OF AIR

• (1) Mechanical ventilation- This reduces vitiated air and bacterial concentration.
• (2) Ultraviolet radiation- This is highly effective against virus,bacteria, fungi etc. It is used in operation theatres and infectious disease wards.
• (3) Chemical mists, Triethylene glucol vapours are used to destroy bacteria in droplet nuclei and dust.
• (4) Dust control- By application of oil to floors of hospital wards.

AIR POLLUTION IN INDIA��

Air pollution in India is a serious health issue. Of the 30 most polluted cities in the world, 21 were in India in 2019. As per a study based on 2016 data, at least 140 million people in India breathe air that is 10 times or more over the WHO safe limit and 13 of the world's 20 cities with the highest annual levels of air pollution are in India. 51% of the pollution is caused by industrial pollution, 27 % by vehicles, 17% by crop burning and 5% by fireworks. Air pollution contributes to the premature deaths of 2 million Indians every year. Emissions come from vehicles and industry, whereas in rural areas, much of the pollution stems from biomass burning for cooking and keeping warm. In autumn and spring months, large scale crop residue burning in agriculture fields – a cheaper alternative to mechanical tilling – is a major source of smoke, smog and particulate pollution. India has a low per capita emissions of greenhouse gases but the country as a whole is the third largest greenhouse gas producer after China and the United States.

AIR QUALITY INDEX��

AIR QUALITY INDEX

An air quality index is used by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become. Public health risks increase as the AQI rises. Different countries have their own air quality indices, corresponding to different national air quality standards

DISEASE CAUSED BY AIR POLLUTION :

• Diseases caused by air pollutants kill and hospitalize millions of people every year. Estimates by the World Health Organization imply that one out of every eight deaths in the world is due to conditions associated with air pollution. New research has established stronger links between both outdoor and indoor air pollution and the development of respiratory and cardiovascular diseases. The most common diseases caused by air pollution include ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung cancer and acute lower respiratory infections in children.

• “Ischemic heart disease, or coronary heart disease, is linked with the buildup of calcium or other materials like fat within the coronary artery,” explains says Kevin Wood, Vice President Sales & Marketing at Camfil USA. “This leads to blockages which prevent blood from reaching the heart and other areas of the body. Recent research indicates that air pollution accelerates the blockage of arteries, leading to increased incidences of ischemic heart disease.”
• Particulate air pollution has been linked with strokes, which occur when the blood supply to the brain is cut-off. Strokes can easily lead to brain damage or death.
• COPD refers to not a single disease, but multiple diseases which make it difficult to breathe. These diseases include bronchitis and emphysema, and both conditions can be caused by damage to the lungs from air pollutants.

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• Lung cancer is the uncontrolled division of cells within the lungs, and it is associated with air pollutants, especially particulate matter pollution, and secondhand smoke.
• Lower respiratory infections often manifest as pneumonia, though they can show up as other ailments as well. Children are especially vulnerable to developing acute lower respiratory tract infections because their bodies and lungs are still developing, and emissions of soot and other pollutants hit them harder than adults.

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