The document summarizes information about the composition of air and air pollution. It states that air is a mixture of 78% nitrogen and 21% oxygen along with trace amounts of other gases like carbon dioxide and water vapor. It also lists some of the minor components in air like sulfur dioxide, methane, and ozone, and their concentrations. The document then discusses how air is separated into its components through fractional distillation of liquefied air. It also explains that poorly maintained scrubbers can spread bacteria and cause diseases like Legionnaires' disease. Finally, it defines air pollution and lists some common air pollutants and gases that can cause suffocation by displacing oxygen in the air.

1. Air mixtures

2. Air is a mixture of gases - 78% nitrogen and 21% oxygen -
with traces of water vapor, carbon dioxide, argon, and
various other components

3. Other components in air
•Sulfur dioxide - SO2 - 1.0 parts/million (ppm)
•Methane - CH4 - 2.0 parts/million (ppm)
•Nitrous oxide - N2O - 0.5 parts/million (ppm)
•Ozone - O3 - 0 to 0.07 parts/million (ppm)
•Nitrogen dioxide - NO2 - 0.02 parts/million
(ppm)
•Iodine - I2 - 0.01 parts/million (ppm)
•Carbon monoxide - CO - 0 to trace (ppm)
•Ammonia - NH3 - 0 to trace (ppm)

4. GASES OF THE AIR
The air around us is a mixture of gases, mainly nitrogen and oxygen, but containing much smaller
amounts of water vapor, argon, and carbon dioxide, and very small amounts of other gases. Air also
contains
suspended dust, spores, and bacteria. Because of the action of wind, the percent composition of air
varies only
slightly with altitude and location. The table indicates the composition of a typical sample of air after
all water
vapor and suspended particles have been removed.
The amount of water in the air varies tremendously with
location, temperature, and time. In deserts and at low temperatures
the content of water vapor can be less than 0.1% by volume. In
warm, humid zones, the air may contain over 6% water vapor.
Air is the commercial source for many of the gases it contains.
It is separated into its components by fractional distillation of
liquefied air. Before air is liquefied, water vapor and carbon dioxide
are removed, because these substances solidify when cooled
and would clog the pipes of the air liquefaction plant. The dry,

5. nitrogen and about 1.25% noble (or “inert”) gases, argon, neon, krypton, and xenon. Nitrogen is second only to
sulfuric acid in the volume produced by the U.S. chemical industry. Its major uses are as an inert blanketing
atmosphere in chemical processing (14%), electronics (15%), and, in liquid form, as a freezing agent (21%).
Nitrogen is used to make agricultural fertilizers, such as ammonia and nitrates. It is also used in the production
of acrylonitrile, CH2=CHCN, which is important in the manufacture of synthetic fibers such as Orlon, and in the
production of cyanamide, HN=C=NH, which is polymerized to Melamine plastic. Because it is a very poor
oxidizing agent, nitrogen is used to pack oxidizable foods, such as ground coffee, and as an inert atmosphere
in
the manufacture of electronic components. Liquefied nitrogen, because it is very cold, is used extensively to
chill
materials for preservation, as in freeze-drying of foods, and in manufacturing processes that require low
temperatures,
such as machining of aluminum.

6. CO2-free air is compressed to about 200 atmospheres. This compression
causes the air to become warm, and the heat is removed
by passing the compressed air through radiators. The cooled, compressed
air is then allowed to expand rapidly. The rapid expansion
causes the air to become cold, so cold that some of it condenses.
By the alternate compressing and expanding of air, most of it can
be liquefied.
Nitrogen is obtained from liquid air by distillation at
-196EC. The gas obtained by this process is actually a mixture of

7. Common Pressure Units frequently used as
alternative to "one Atmosphere"
•76 Centimeters (760 mm) of Mercury
•29.921 Inches of Mercury
•10.332 Meters of Water
•406.78 Inches of Water
•33.899 Feet of Water
•14.696 Pound-Force per Square Inch
•2116.2 Pounds-Force per Square Foot
•1.033 Kilograms-Force per Square Centimeter
•101.33 Kilopascal

8. Air Scrubber
Scrubber systems are a diverse group of air pollution control devices that can be used to remove some
particulates and/or gases from industrial exhaust streams. The first air scrubber was designed to
remove carbon dioxide from the air of an early submarine, the Ictineo I, a role which they continue to
be used for to this day. Traditionally, the term "scrubber" has referred to pollution control devices that
use liquid to wash unwanted pollutants from a gas stream. Recently, the term is also used to describe
systems that inject a dry reagent or slurry into a dirty exhaust stream to "wash out" acid gases.
Scrubbers are one of the primary devices that control gaseous emissions, especially acid gases.
Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation.

9. Wet scrubbing
The exhaust gases of combustion may contain substances considered harmful to
the environment, and the scrubber may remove or neutralize those. A wet
scrubber is used to clean air, fuel gas or other gases of various pollutants and
dust particles. Wet scrubbing works via the contact of target compounds or
particulate matter with the scrubbing solution. Solutions may simply be water
(for dust) or solutions of reagents that specifically target certain compounds.
Process exhaust gas can also contain water soluble toxic and/or corrosive gases
like hydrochloric acid (HCl) or ammonia (NH3). These can be removed very well
by a wet scrubber.

10. Dry scrubbing
A dry or semi-dry scrubbing system, unlike the wet scrubber, does not saturate the flue gas stream
that is being treated with moisture. In some cases no moisture is added, while in others only the
amount of moisture that can be evaporated in the flue gas without condensing is added. Therefore,
dry scrubbers generally do not have a stack steam plume or wastewater handling/disposal
requirements. Dry scrubbing systems are used to remove acid gases (such as SO2 and HCl) primarily
from combustion sources.
There are a number of dry type scrubbing system designs. However, all consist of two main sections or
devices: a device to introduce the acid gas sorbent material into the gas stream and a particulate
matter control device to remove reaction products, excess sorbent material as well as any particulate
matter already in the flue gas.
Dry scrubbing systems can be categorized as dry sorbent injectors (DSIs) or as spray dryer absorbers
(SDAs). Spray dryer absorbers are also called semi-dry scrubbers or spray dryers.

11. Bacteria spread
Poorly maintained scrubbers have the potential to spread disease-causing bacteria. The problem is
a result of inadequate cleaning. For example, the cause of a 2005 outbreak of Legionnaires' disease
in Norway was just a few infected scrubbers. The outbreak caused 10 deaths and more than 50
cases of infection.

12. The Importance Of Air
Other planets have sunlight, but the Earth is the only planet we know that has air and water. Without
air and water, the Earth would be unable to sustain life.
A diverse community of plant and animal life has thrived on this planet for millions of years, sustained
by the sun and supported by the soil, water and air.

13. Definition of air pollution
Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is,
amounts which could be harmful to the health or comfort of humans and animals or which could cause
damage to plants and materials.
The substances that cause air pollution are called pollutants. Pollutants that are pumped into our
atmosphere and directly pollute the air are called primary pollutants. Primary pollutant examples
include carbon monoxide from car exhausts and sulfur dioxide from the combustion of coal.
Further pollution can arise if primary pollutants in the atmosphere undergo chemical reactions. The
resulting compounds are called secondary pollutants. Photochemical smog is an example of this.

14. pollutants
Air pollutants mainly occur as a result of gaseous discharges from industry and motor vehicles. There
are also natural sources such as wind-blown dust and smoke from fires.
Some forms of air pollution create global problems, such as upper atmosphere ozone depletion and
global warming. These problems are very complex, and require international cooperative efforts to
find solutions.

16. Gases that causes suffocation
An asphyxiant gas is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen
concentration in breathing air. Breathing of oxygen-depleted air can lead to death by asphyxiation
(suffocation). Because asphyxiant gases are relatively inert and odorless, their presence in high
concentration may not be noticed, except in the case of carbon dioxide (hypercapnia).
Toxic gases, by contrast, cause death by other mechanisms, such as competing with oxygen on the
cellular level (e.g., carbon monoxide) or directly damaging the respiratory system (e.g., phosgene).
Far smaller quantities of these are deadly.
Notable examples of asphyxiant gases are nitrogen, argon, and helium. Along with trace gases such as
carbon dioxide and ozone, these comprise 79% of Earth's atmosphere. The atmosphere is mostly
harmless because the remaining 21% is O2.

17. Asphyxia hazard
Asphyxiant gases in the breathing air are normally not hazardous. Only where elevated concentrations of
asphyxiant gases displace the normal oxygen concentration a hazard exists. Examples are:
Environmental gas displacement
Confined spaces, combined with accidental gas leaks, such as mines, submarines,refrigerators, or other confined
spaces
Fire extinguisher systems that flood spaces with inert gases, such as computer data centers and sealed vaults
Large-scale natural release of gas, such as during the Lake Nyos disaster in which volcanically-released carbon
dioxide killed 1,800 people.
Release of helium boiled off by the energy released in a magnet quench such as the Large Hadron Collider or a
magnetic resonance imaging machine.
Climbing inside an inflatable balloon filled with helium
Direct administration of gas
Exclusive administration, such as inhaling the contents of a balloon filled with helium
Inadvertent administration of asphyxiant gas in respirators
Use in suicide and erotic asphyxiation

18. ADITI SHARMA
GRADE :8 “A”