8/21/2012 4:31:00 PM
Addison McClaugherty
Crowley
Period 1
8/20/12
Chapter 20: Air Pollution
Atmosphere: A gaseous envelope surrounding the earth containing four
gases, nitrogen, oxygen, argon, and carbon dioxide.
Ecosystem services:
 The atmosphere blocks the surface of the earth from much of the
ultraviolet radiation coming from the sun.
 Moderating the climate
 Redistributing water in the hydrologic cycle.
Air Pollution
Air pollution contains gases, liquids, or solids present in the atmosphere in
high enough levels to harm humans, other organisms, or materials.
Where does it come from?
 Natural sources – Ex. Forest Fire, Volcano eruption
 Human activities
o Major contributor towards global air pollution
o Harmful – when substances precipitate from solid and settle
on land and surface waters
o Alter chemistry of the atmosphere
More significant than overall human contribution is much of air pollution is
concentrated in densely populated areas.
7 most
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important types of air pollutants:
Particulate matter
Nitrogen oxides
Sulfur oxides
Carbon oxides
Hydrocarbons
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Ozone
Air toxics
Primary Air Pollutants: are harmful chemicals that enter directly into the
atmosphere.
 Major Ones
o Carbon oxides
o Nitrogen oxides
o Sulfur dioxide
o Particular matter
o Hydrocarbons
Secondary Air Pollutants: are harmful chemicals that form from other
substances released into the atmosphere.
 Ozone and sulfur trioxide are secondary air pollutants because they
are formed in a chemical reaction in the atmosphere.
Particular Matter: consists of thousands of different solid and liquid
particles suspended in the atmosphere.
 Solid Particulate matter
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o Dust
Liquid matter
o Mists
Particulate matter: reduces visibility by scattering and absorbing
sunlight.
o Includes pollutants, Ex. Soil particles, soor, lead, asbestos,
sea salt, sulfuric acid droplets.
o Corrodes metals
o Erodes buildings and sculptures when air is humid
o Soils clothing and draperies
Eventually particular matter settles out of atmosphere but some microscopic
particles stay suspended for longer period of time
 Dangerous when inhaling
o Contains traces of over 100 different chemicals
Nitrogen Oxides: are gases produced by the chemical interactions between
nitrogen and oxygen when a source of energy, such as combustion of fuels,
produces high temperatures.
 Inhibits plant growth
 Causes asthma
 Involved in production of photochemical smog and acid deposition
 Corrodes metals
 Textiles to fade and deteriorate
Global warming: nitrous oxides trap heat in the atmosphere and is there for
a greenhouse gas which depletes the ozone in the stratosphere
Sulfur Oxides: gas produced by chemical reactions between sulfur and
oxygen.
 Colorless, nonflammable gas but has strong odor
 Causes acid deposition that corrodes metals and damage stone and
other materials
Sulfuric acids and sulfate salts produced in the atmosphere from sulfur
oxides damage plants and irritates the respiratory system of humans and
animals.
Carbon Oxides: are the gases carbon monoxide and carbon dioxide.
 Carbon monoxide is produced in the largest quantities of any
atmospheric pollutant except for carbon dioxide.
 Carbon dioxide is poisonous and reduces bloods ability to transport
oxygen.
o Greenhouse gas, its buildup in the atmosphere is linked with
global warming
Hydrocarbon: is a diverse group of organic compounds that contain only
hydrogen and carbon
 Simplest hydrocarbon is methane
o Principle component in natural gas
 Medium sized hydrocarbons such as benzene are liquid at room
temperature although many are volatile and evaporate readily.
 Largest is paraffin
Variety of effects on humans and other animals such as injury to the
respiratory system and causes cancer.
 Methane is a potent greenhouse linked to global warming
Ozone: is a form of oxygen considered a pollutant in one part of the
atmosphere but an essential component in another.
 Oxygen reacts with UV radiation coming from the sun in the
stratosphere to form the ozone.
 Pollutants have been reacting with the stratospheric ozone,
breaking it down into molecular oxygen
Ozone in the troposphere is a layer of atmosphere that is a human-made air
pollutant.
 Secondary air pollutant
 Photochemical smog, reduces visibility and causes health problems.
 Stresses plants
 Chronic ozone exposure lowers crop yields, forest decline and
contributes to global warming
Hazardous air pollutants:
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Chlorine, lead, hydrochloric acid, formaldehyde, radioactive
substances, and fluorides
Potentially harmful
Clean Air Act Amendments of 1990 meant to limit release of them
Industrial smog:
 Smoke pollution composed of sulfur oxides and particulate matter
photochemical smog:
 brownish-orange haze formed by chemical reactions involving
sunlight nitrogen oxides, and hydrocarbons.
temperature inversions:
 layer of cold air temporarily trapped near the ground by a warmer
upper layer. Temperature inversions that persist in congested urban
areas cause air pollutants to accumulate to dangerous levels.
Health effects:
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irritation the eye, inflamed respiratory tract, and suppressed
immune system. Constriction of airways which impairs the lungs
ability to exchange gases
Children have a bigger threat than adults because pollutants
impedes lung development. They have weaker lungs and more
likely to develop respiratory problems
Electrostatic Precipitators and Scrubbers:
 An electrode imparts a negative charge to particulates in the dirty
gas. These particles are attracted to the positively charged
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precipitator wall and then fall off into the collector.
In a scrubber, mists of water droplets trap particulates in the dirty
gas.
The toxic dust produced by electrostatic precipitators and then
polluted sludge produced by scrubbers bust be safely disposed of or
they will cause soil or water pollution.
Clean Air Act
 Authorizes the EPA to set limits on how much specified air
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pollutants are permitted in the states.
Huge improvement in lead being released into the atmosphere
along with other pollutants declining
Global Distillation effect: process in which volatile chemicals evaporate
from land as far away as the tropics and are transported by winds to higher
latitudes, where they are condense and fall to the ground.
 Volatile chemicals contaminate some remote artic regions in result
of the global distillation effect.
Sick building syndrome: is the presence of air pollution inside office
buildings that can cause eye irritations, nausea, headaches, respiratory
infections, depression, and fatigue.
 Radon is a serious indoor air pollutant