What Causes Air

Pollution?

 

Areas of India and Bangladesh have air that is so polluted it harms people’s health.

 

When harmful substances build up in the air to unhealthy levels, the result i s air p olluti on.

 

A volcano, for example, can spew clouds of particles and sulfur dioxide, SO 2 Natural pollutants also include dust, pollen, and spores.

 

Primary and Secondary Pollutants

 

A pollutant that is put directly into the air by human activity is called a prim ary polluta nt . An example of a primary pollutant is soot from smoke. Figure 1.1 shows some sources of primary air pollutants. Second ary poll ut- an ts f orm when primary pollutants react with other primary pollutants or Ground-level ozone forms when the ultraviolet rays of the sun cause emissions from cars, trucks, and other sources to react with oxygen in the atmosphere.

 

FIGURE 1.1

 

Primary Air Pollutants Each day in the United States, hundreds of thousands of tons of polluting emissions that result from human activity enter the air.

SECTION 1

 

Objectives

 

ame five primary air ollutants and give sources

 

for each.

 

ame the two major sources of ir pollution in urban areas.

 

escribe the way in which mog forms.

 

xplain the way in which a thermal inversion traps air pollution.

 

Key Terms air pollution

primary pollutant secondary pollutant smog

temperature inversion

 

CHECK FOR UNDERSTANDING

 

Explain How is ground-level ozone an example of a secondary pollutant?

SECTION   1

 

Focus and Motivate

 

Objectives

Pollution from automo-biles and industry is discussed, along with smog and temperature inversions.

 

 

Classroom Catalyst

 

Divide the class into small groups, and tell them to use humor, as Cohen did, to complete the following sentence: “You know the air is polluted when…”

 

	80		Sources of Primary Air Pollutants in the U.S. (Per Day)
tons)	70					Carbon monoxide (CO)
	60					Nitrogen oxides (NOx)
of						Particulate matter (PM)
(inthousands	50					Sulfur oxides (SOx)
						Volatile organic compounds (VOCs)
	40
Emissions	30
	20
	10
	0
		Electricity production	Industry	Transportation		Other sources

 

Source: U.S. Environmental Protection Agency.

 

 

 

Differentiated Instruction	Chapter 12:  Air303

 

INCLUSION

 

Have students use a word processor, pencil and paper, or posterboard to list the sources of primary air pollutants in Figure 1.1 Have students estimate how much pollution is produced by each source of primary air pollution.

Classroom Discussion

 

Comparing Cigarette Smoke and Pollution   Poll the class, and ask how Ask, “If cigarette manufacturers are being held accountable for the health effects of the use of their products, should industries be accountable for the effects of the pollutants they discharge into the air?”

 

 

Answers

 

Check for Understanding

 

Ground-level ozone is a secondary pollutant because it forms when primary pollutants react with oxygen in the presence of UV radiation.

 

 

 

 

 

 

 

Chapter 12: Air               303

 

Teach

 

Misconception Alert!

 

Invisible Pollutants   Many people Have students compile their results in a table that lists the acceptable amounts allowed in the air, the levels in your community, and the health problems associated with each pollutant.

FIGURE 1.2

 

 

Pollutant

 

Carbon monoxide (CO)

 

 

 

Nitrogen oxides (NO x )

 

 

 

 

Sulfur dioxide (SO 2 )

 

 

 

 

Volatile organic compounds (VOCs)

 

Particulate matter (particulates or„PM)

PRIMARY AIR POLLUTANTS

 

Description	Primary Sources	Effects
CO is an odorless, colorless,	Sources of CO are cars,	CO interferes with the blood’s ability
It is	trucks, buses, small	to carry oxygen, slowing reflexes
produced by the incomplete	engines, and some industrial	In high
burning of fossil fuels.	processes.	concentrations, CO can cause death.
When combustion (burning)	NO x comes from burning fuels	NO x can make the body vulnerable to
temperatures exceed	in vehicles, power plants, and	respiratory infections, lung diseases,
538°C, nitrogen and	industrial boilers.	NO x contributes to the
oxygen combine to form		brownish haze seen over cities and to
nitrogen„oxides.		acid„precipitation.
SO 2 is produced by	SO 2 comes mostly from	SO 2 contributes to acid precipitation as
chemical interactions	burning fossil fuels.	Secondary pollutants that
between sulfur and oxygen.		result from reactions with SO 2 can harm
		plant life and irritate the respiratory
		systems of humans.
VOCs are organic chemicals	VOCs come from burning	VOCs contribute to smog formation and
that vaporize readily and	Vehicles are a major	can cause serious health problems, such
form toxic fumes.	source of VOCs.	They may also harm plants.
Particulates are tiny	Most particulates come from	Particulates can form clouds that
particles of liquid or	construction, agriculture,	reduce visibility and cause a variety of
solid„matter.	Vehicles	Particulates have
	and industrial processes also	As well, they
	contribute particulates.	may corrode metals and erode buildings
		and„sculptures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Differentiated Instruction

 

 

 

 

 

 

 

 

Connect to LAW

 

Off with His Head!

 

Around 1300 CE “Be it known to all within the sound of my voice,” King Edward I said, “whosoever shall be found burning coal shall suffer the loss of his head.”

 

304 Unit 4: Water, Air, and Land

Sources of Primary Air Pollutants

 

As shown in Figure 1.2 above, household products, power plants, and motor vehicles are sources of primary air pollutants such as carbon monoxide, nitrogen oxide, sulfur dioxide, and chemicals called volatile organic compounds Carbon monoxide gas is an important VOCs are also found in many household products.

 

Sources of coarse particles are cement plants, mining operations, incinerators, wood-burning fireplaces, fields, and roads.

 

inclusion

 

Paired Summarizing   Have each student pair with a partner and take turns reading and summarizing the primary pollutants identified in Figure 1.2 Student pairs should also offer two examples of each category of primary pollutant.

Group Activity

 

Collecting Particulate Matter   Check the air Students should also

As an extension, try this experiment at different times of the year and in different locations in your community.

 

304 Unit 4: Water, Air, and Land

The History of Air Pollution

 

One man was even executed for disobey-ing this medieval “clean air act.”

 

As represented in Figure 1.3 , most air pollution in industrialized countries comes from mo-tor vehicles and industry.

ECO FACT

 

Sea-Coal

 

The smoke emanated from London homes and factories and combined with fog to produce smog.

Global Awareness

 

Looking to Latin America   Enrique To get to work or school, everyone

 

Motor Vehicle Emissions

 

The rest was from trucks and‹buses.

FIGURE 1.3

 

Sources of Air Pollution The refinery shown in this photograph is a The truck in the foreground is emitting nitrous oxide into the atmosphere.

would ride public transportation or bicycles, or they would walk.

 

 

Make It Relevant

 

Local Air Quality   Air quality varies Have students

	Controlling Vehicle Emissions
	The Clean Air Act, passed in 1970 and
	strengthened in 1990, gives the Envi-
	ronmental Protection Agency (EPA) the
	authority to regulate vehicle emissions
	The EPA required
	the gradual elimination of lead in gaso-
	line, and as a result, lead pollution has
	been reduced by more than 90 percent in
	In addition, catalytic
	converters, which are required in auto-
	mobiles, clean exhaust gases of pollutants
	before the pollutants are able to exit the
	The EPA indicates that light-duty
	cars and trucks in 2010 burned fuel ap-
	proximately 70 percent more efficiently
	and with about 40‹percent fewer emis-
	sions of carbon dioxide than they did in
	In addition, cars and trucks produce
Images	approximately 95 percent fewer emissions
	of pollutants other than carbon dioxide
©A.T.Willett/Alamy	than they did in the 1970s.

 

 

 

 

Chapter 12:  Air

305

What are the weather conditions that lead to the worst and best air quality in your area?”

 

 

Connect to History

 

“Valley of the Smokes”   Centuries ago, Native Americans knew the Los Angeles Basin as the “Valley of the Smokes” because frequent temperature inversions trapped the smoke from their fires, casting a gray pall over the valley.

 

Group Activity

 

Reducing Auto Emissions   In the 1970s, Honda What improvements are planned to meet the tougher emission standards of the future?”

Students may mention electric cars, hybrid cars, dual fuel systems that permit a car to use either natural gas or gasoline, and solar cars.

 

Chapter 12: Air               305

 

Teach continued

 

Homework

Evaluating Car Use   Tell students to Are there any trips that might make

Connect to MATH

 

Utility Incentives for Zero-emission Vehicles

 

How much would you save if you had three electric cars?

California Zero-Emission Vehicle Program

 

A catalytic converter, as shown in Figure 1.4 ZEV programs have also been adopted in Maine, Massachusetts, New York, and Vermont.

 

Zero-emission vehicles have no tailpipe emissions, no emissions from One type is clean, fuel-efficient hybrid cars, which are powered by both batteries and gasoline engines.

 

As of 2011, such hydrogen-powered ve-hicles are still mostly in the prototype stage of development.

 

Suggest that students include their responses in their science journal.

 

 

EcoSmart

FIGURE 1.4

 

Car Emission The catalyst material in a catalytic converter (top) speeds up a chemical reaction that changes exhaust The text below the images shows a car’s contribution to air pollution.

 

Allowance Trading System   The EPA’s In this system, 1 ton of sulfur dioxide (SO 2 Sulfur dioxide allow-ances are inexpensive and can be bought

 

 

 

Interior

 

•     Car seats may be covered in plastic that contains a volatile organic compound called vinyl chloride .

 

Body and Frame

 

•    Steel smelters send thousands of metric tons of sulfur dioxide into the air each year.

 

•    Many auto factories in Mexico, Eastern Europe, and some Asian countries lack pollution-control devices.

 

Fuel Tank

 

•     When filling the car with gasoline, VOCs escape†into†the†atmosphere.

 

 

 

 

 

 

 

 

 

 

Exhaust

 

•    Car exhaust is a major source of nitrogen oxides, carbon monoxide, and hydrocarbons.

 

•    In developing countries, car exhaust may contain over a thousand poisonous substances.

 

Purchasing one allowance will reduce a company’s allowable SO 2 emissions in a given year by 1 ton.

 

 

Answers

 

Connect to Math

 

$0.025 × 150 hours = $3.75/month $3.75 × 12 months = $45.00 $45.00 × 3 vehicles = $135.00/year

 

 

 

 

306 Unit 4: Water, Air, and Land

Differentiated Instruction

 

pre-ap

 

The Yellow Bikes Program   In an effort to The idea is that a resident

 

Have students investigate the possibility of instituting a “Yellow Bikes” program in their area.

 

FIGURE 1.5

 

Industrial Pollution In 1996, the federal government established standards to reduce emissions of VOC-producing chemicals used in dry cleaning.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Industrial Air Pollution

 

Power plants that produce electricity emit at least two-thirds of all sulfur dioxide and more than one-third of all nitrogen oxides that pollute the air.

 

Some industries, such as the dry cleaning industry shown in Figure 1.5 Oil refineries, chemical manufacturing plants, furniture refinishers, and automobile repair shops also contribute to the VOCs in the air.

 

	Regulating Air Pollution from Industry
	The Clean Air Act requires many industries to use scrubbers or other
	Scrubbers remove some of the more harmful
	A scrubber , as shown
	in Figure 1.6 , is a machine that moves gases through a spray of water that
	dissolves many pollutants.
	Electrostatic precipitators are machines used in cement factories and
	In
	an electrostatic precipitator, gas containing dust particles is blown through
Newman/PhotoEdit	An electrical charge is transferred to the dust particles,
	Electrostatic precipitators
	which causes them to stick to one another and the sides of the chamber.
©Michael	The clean gas is released from the chamber, and the concentrated dust
	plants from the air each year in the United States.
	remove more than 20 million tons of ash generated by coal-burning power

 

 

 

 

Group Activity

 

Air Pollution and the Individual   Divide the At what point would the level of air pollutants in the air be high enough for me to take action?”

ECO FACT

 

Air Pollution’s Impact on Birds

 

The two species of birds respond differently

 

One

 

When heavy metal

 

emissions from the smelter decreased, a rapid improvement in breeding

 

success and a decrease in the heavy metal found in the bones of nestlings was observed.

 

 

 

FIGURE 1.6

 

Scrubber Scrubbers work by spraying gases with water, which removes many pollutants.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHECK FOR UNDERSTANDING

 

Describe Name two pollution-control State how they help to limit the amount of pollutants in air.

 

Chapter 12:  Air

307

Demonstration

 

Temperature Inversion   Fill the bottom Ask students to observe what happens. (The smoke Thus, the smoke is trapped below with the cooler air just as air pollutants are trapped in an urban environment.) Point These conditions include cloud cover, which reduces warming at the Earth’s surface, and lack of wind.

 

 

 

Connect to Geology

 

Vog and Laze   Vog is volcanic smog that Physical and chemical interactions create white plumes of hydrochloric acid and concentrated salt water.

 

 

Answers

 

Check for Understanding

 

An electrostatic precipitator reduces pollution by removing dust particles from smokestacks.

 

 

 

 

 

 

Chapter 12: Air               307

 

Assess and Reteach

 

Quiz

1. What does VOC stand for? (volatile organic compound)

 

2. What are the main causes of smog? (sunlight, air, automobile exhaust, and ozone are the main causes of smog.)

 

Alternative

Assessment

 

Smog and Ozone Alerts   Ask students They should also include advice about how people can minimize their exposure during the alert and about what individuals can do to help alleviate the problem.

 

 

Reteach

FIGURE 1.7

 

Smog The diagram below shows Large cities with dry, sunny climates and millions of automobiles often suffer from smog.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FIGURE 1.8

 

Air Circulation Normal air A temperature inversion, in which pollutants are trapped near Earth’s surface, is shown at right.

Smog

 

When air pollution hangs over urban areas and reduces visibility, it is calle d sm og As you can see in Figure 1.7 , smog results from chemical reactions that involve sunlight, air, automobile exhaust, and ozone.

 

Pollutants released by vehicles and industries are the main causes of smog.

 

Temperature Inversions

 

The warm air rises through the cooler air above and carries pollutants away from the ground and into the atmo-sphere.

 

Usually, air temperatures decrease with altitude, but sometimes a temperatu re i nversi on o ccurs when the air above is warmer than the air below. Figure 1.8 Los Angeles, which is surrounded on three sides by mountains, often has temperature inversions that trap smog in the city.

 

Pollution Sources   Write the following pollution sources on the board:

Section 1 Formative Assessment

 

Finally, discuss the types

 

of pollutants that each source usually emits and possible remedies for those pollutants.

Reviewing Main Ideas

 

1. Name five primary air pollutants, and give important sources for each.

 

2. Name the two major sources of air pollution in urban areas.

 

3. Describe the way in which smog forms.

 

4. Define the term temperature inversion Explain how temperature inversion traps pollutants near Earth’s surface.

Critical Thinking

 

5. Making Decisions Read the passage on the Should automobile makers be made to adhere to quotas of zero-emission vehicles set by states, even if it causes automakers to lose revenue?

 

6. Analyzing Relationships Can you think of any other possible type of pollution-control device that could be used to remove particulates from smokestacks in a manner similar to an electrostatic precipitator?

 

Answers to Formative Assessment

 

1. Answers will vary, but should reflect the material in Figure 1.2.

 

2. The two major sources of air pollution in urban areas are motor vehicles and industry.
3. Automobile exhaust reacts with air and sunlight to form ozone, and ozone reacts with automobile exhaust to form smog.

 

4. When the air below is cooler, pollutants stay near the ground.

 

 

 

5. Students should weigh both short-term and long-term economic and environmental consequences.
6. Students may describe pollution-control devices that use a centri-fuge to collect pollutants.

 

 

308 Unit 4: Water, Air, and Land