PRINCIPLES OF ENVIRONMENTAL ENGINEERING

PP-404

AIR POLLUTION

ATMOSPHERE It is the gaseous envelope surrounding the earth and extends up to

400 kilometers above the earths surface.

The atmosphere, which is a gaseous cover, protects the earth from cosmic radiations

Provides life sustaining Oxygen , the macronutrient Nitrogen and Carbon dioxide needed for photosynthesis.

The atmosphere screens the dangerous UV radiations from the sun

In addition the atmosphere is the medium of carriage of water from the oceans to the land in the hydrological cycle

COMPOSITION OF ATMOSPHERE

GASES Nitrogen Oxygen Argon

Carbon dioxide Neon

Krypton Hydrogen

Xenon Ozone

Carbon monoxide Sulfur dioxide

Nitrogen dioxide Ammonia

WATER VAPOR 0.1% - 5% (by volume)

The vapor creates different weather conditions

AIRBORNE PARTICLES All solid and liquid particles in air and transported by air

Aerosols Suspension of

liquid/solid particles in air

Smog Dust cloud

Particulates All

solid/liquid particles in

air Dust Soot

Fly ash

MAJOR LAYERS IN ATMOSPHERE

AIR POLLUTION Air pollution may be defined as the presence of one or

more contaminants (Chemicals, Dust, Smoke, Fume, Particulate Matter etc.) in such quantities and duration, which is detrimental to the health of plants and animals,

property

SOURCES OF AIR POLLUTION

NATURAL ?

MAN MADE ?

CLASSIFICATION OF AIR POLLUTANTS

ORIGIN COMPOSITION STATE OF MATTER

PRIMARY SECONDARY

ORGANIC INORGANIC

PARTICULATES

GAS

SOLIDS LIQUIDS

MAJOR AIR POLLUTANTS Air pollutants can be classified in to different ways.

They are: Primary Pollutants. Those directly emitted into the

atmosphere. e.g. CO, NO2, SO2, Hydrocarbons. Secondary Pollutants. Those derived due to the

interaction between the primary pollutants and / or the gases in the atmosphere. (Ozone, Smog, Per oxy Acyl Nitrate).

Organic Pollutants (Hydrocarbons, Aldehydes, Ketones, Alcohols, etc.).

Inorganic Pollutants. Oxides of Carbon, Nitrogen, Sulfur, Halogen Compounds, HNO3, H2SO4, Ozone, Metallurgical dust, Fly ash, Silica etc.

Particulate matter. Fine solid dust or liquid droplets like smoke, fumes, fog, smoke, sprays etc.

IMPORTANT TERMINOLOGIES

Note: Rest from the handout or from any book

INDOOR AIR POLLUTION

AIR POLLUTION METEOROLOGY Pollutants discharged into the atmosphere are transported to

according t the wind characteristics

Intensity of air pollution continuously changes with the meteorological conditions

METEOROLOGICAL FACTORS Wind direction and speed

Temperature

Atmospheric stability

Humidity

Precipitation

Solar radiation

a) WIND SPEED AND DIRECTION:

Pollutants discharged near the ground are effected by wind speed and direction:

1. Terrain is flat and discharges occur at sufficient height

Concentration of pollutant in a particular area is inversely proportional to the wind speed

Seasonal variations Estimation of pollutants

Characteristics of any location Important in EIA for site selection

2. Terrain is hilly

Depends upon the vertical stability of the atmosphere

b) TEMPERATURE:

I. Environment lapse rate II. Dry Adiabatic lapse rate 10C/1000m III. Wet adiabatic lapse rate 6C/1000m

c) ATMOSPHERIC STABILITY:

ATMOSPHERIC STABILITY

ABSOULTELY STABLE ATMOSPHERE

ABSOULTELY UNSTABLE ATMOSPHERE

CONDITIONALLY UNSTABLE ATMOSPHERE

d) HUMIDITY:

Air with relative humidity less than 30% dry

Air with relative humidity greater than 65% uncomfortable

Influence the dispersion of pollutants

Effects the stability of environment

Formation of dew, fog, mist are all consequences of humidity

e) SOLAR RADIATION:

Driving factor for photochemical reactions