The Threat of Air Pollution - Breal -...

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Copyright © 2013 Pearson Education, Inc.

The Atmosphere:

An Introduction to

Meteorology, 12th

Lutgens • Tarbuck

Lectures by:

Heather Gallacher,Cleveland State University

Chapter 13: Air Pollution



The Threat of Air Pollution


The Threat of Air Pollution

� Natural air pollution:

� Dust storms, ash from volcanoes, pollen and spores, and

smoke from wildfires are all forms of natural air pollution.

� Human caused air pollution:

� Smoke, soot, and other gases from chimneys, smog,

and carbon monoxide are among the human causes of

air pollution.

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Sources and Types of Air Pollution

� Air pollutants are particles and gases in

concentrations that endanger the health and well-

being of organisms.

� Primary pollutants are emitted directly from identifiable

sources.

� Secondary pollutants are produced via chemical reactions

in the atmosphere with primary pollutants.



� Primary pollutants:

� These pollutants consist of particulate matter, which is

a mixture of solid particles and liquid droplets found in

the air.

� Fine particles are less than 2.5 micrometers in diameter

� These are from combustion, wood burning, and power

generation.

� Coarse particles are less than 10 micrometers.

� These particles come from dirt roads and crushing and grinding

operations.



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� Sulfur dioxide (SO2)

� SO2 is a colorless gas originating from the combustion of

sulfur-containing fuel, such as coal and oil.

� Important sources are power plants, smelters, pulp and paper

mills, and petroleum refineries.

� SO2 is also a cause of acid rain.



� Nitrogen oxide (Nox)

� Nitrogen oxides are gases that form during the high-

temperature combustion of fuel when nitrogen in the air or

fuel reacts with oxygen.

� Motor vehicles and power plants are the primary sources.

� It is also a contributor to acid rain.



� Volatile organic compounds (VOCs):

� VOCs are also called hydrocarbons.

� They encompass a wide array of solids, liquids, and gases.

� Carbon monoxide (CO):

� CO is a colorless, odorless, and poisonous gas produced

by the incomplete burning of coal, wood, and oil.

� More than three-quarters of U.S. emissions are from motor

vehicles and nonroad equipment.

� Lead (Pb):

� Lead was formerly added to gasoline to prevent

engine knock.

� Occasional violations still occur at lead smelters.

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� Secondary air pollution:

� Air pollution in urban and industrial areas is called smog,

a combination of smoke and fog.

� Photochemical reactions are triggered by strong sunlight.

� Nitrogen oxides absorb sunlight in the presence of VOCs.

� It is a noxious mixture of gases and particulates.

� The major component is ozone.



� Volcanic smog (Vog):

� This occurs in active volcanoes.

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Trends in Air Quality



� Clean Air Act of 1970:

� It was responsible for the creation of the Environmental

Protection Agency.

� This legislation set standards for the four primary

pollutants as well as the secondary pollutant.

� Primary

� Particulates

� SO2

� NOx

� CO

� Secondary

� Ozone



� Short term:

� Acute effects refers to levels that might be life threatening

within a period of hours or days.

� Long term:

� Chronic effects occur when levels cause gradual

deterioration of fhysiological functions over a span

of years.

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� Air Quality Index (AQI):

� The AQI is an indicator for reporting daily air quality to

the general public.

� The EPA calculates the AQI for the five pollutants

regulated by the Clean Air Act.

� The AQI scale runs from 0–500.

� Less than 100 on the scale is good.

� Greater than 100 is considered unhealthy.



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Meteorological Factors Affecting

Air Pollution

� Wind as a factor



Air Pollution

� The role of atmospheric stability:

� This determines how far the pollutants will move

vertically.

� Mixing depth is the vertical distance between

Earth’s surface and the height of convectional

movement.

� When air is stable, there is little convection and the mixing

depths are small.

� When air is unstable air, there is greater convection and

the mixing depths are large.



Air Pollution

� Surface temp inversions

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Air Pollution

� Inversions aloft


Acid Precipitation

� Wet deposition:

� Through a series of chemical reactions, pollutants emitted

from sources, such as power-generating plants, ore-

smelting, petroleum refining and motor vehicles of all

kinds, are converted to acids then fall as rain or snow.

� Dry deposition

� Acid-producing chemicals may become incorporated into

dust or smoke and then fall to the ground.


Acid Precipitation

� Extent and potency of acid precipitation

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Acid Precipitation


Acid Precipitation

� Effects of acid precipitation

� It lowers the natural pH of lakes and rivers.

� It reduces agriculture yields.

� It corrodes metals and stone structures.


End Of Chapter 13

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