Air PollutionAny harmful substances that can buildup in the

air to unhealthy levels

Sources of PollutionPrimary Pollutant

- Pollutant put directly into the air by human activity.

-Ex: soot from smoke.

Secondary Pollutant

- Primary pollutant reacts with other primary pollutants or with naturally occurring substances.

-Ex: ground level ozone (emissions react with oxygen)

Primary vs. Secondary Pollutants

Temperature Inversion• Temp. Inversion = when the air above is warmer

than the air below it.• A temperature inversion can trap pollutants near

the Earth’s surface b/c the warm air above doesn’t allow the cooler air to move upward.

• Cities in a valley are more likely to experience temp. inversions (Ex: LA)

Air Pollution

1.What is the most common source of primary air pollutant in the US daily?

2.Which pollutant is released the most?

Types of Pollutants

Carbon Monoxide - from car emissions

Sulfur Dioxide – from burning coal & oil

Carbon Monoxide - Motor Vehicle Emissions

• Almost 1/3 of our air pollution comes from gasoline burned by vehicles.

• Regulation - The Clean Air Act (1970) gives EPA the authority to regulate vehicle emissions in the US.– Eliminated lead in gasoline

(unleaded)– Catalytic converters required

that clean exhaust gases before exiting the tailpipe

Sulfur Dioxide - Industrial Air Pollution

• Many industries, including power plants, burn fuel to produce energy.

• Burning fossil fuels releases, sulfur dioxide, nitrogen oxides, & carbon dioxide into the air.

• Regulation - Clean Air Act requires many industries to use scrubbers or other pollution-control devices. – Scrubbers remove some of the

more harmful substances from emissions

– Electrostatic precipitators remove dust particles from smokestacks.

Environmental Effect ~ Smog• Air pollution that hangs over urban areas and

reduces visibility.

• It results from chemical reactions that involve sunlight, air, auto exhaust, and ozone.

• Caused mainly by auto and industrial exhaust

Effects of SmogEffects on Humans

-Respiratory problems like: - asthma - emphysema - chronic bronchitis

-Eye irritations

-Reduced resistance to colds and lung infections.

Effects on Plants

-Inhibits plant growth

-Damages crops

1. Fossil fuels are burned, releasing sulfur & nitrogen oxides 2. These oxides combine with water in the atmosphere, forming sulfuric acid & nitric acid 3. Acid precipitation falls into lakes, rivers, & streams; killing organisms that live there

Environmental Effect ~Acid Precipitation - precipitation that contains high

concentrations of acid.

How Acidic Is It?• pH is a measure of how acidic a substance is.

• The lower the pH number is, the more acidic a substance is.– Pure water has a pH of 7.0 (neutral)– Normal precipitation is slightly acidic (pH 5.6)– Acid precipitation has a pH of less than 5.0

• pH of eastern US & Canada ranges from 4.2-4.8

Effects of Acid Precipitation

Effects on Soil

-Drop pH of soil

-Nutrients decrease

-Releases aluminum & other toxic metals

Effects on Plants

-Soil changes cause root damage

-Clogged openings on the surfaces of plants.

Effects of Acid PrecipitationEffects on Aquatic

Ecosystems

-Acid can kill fish & other aquatic animals. Aluminum builds up in the gills, suffocating them.

Effects on Humans

-Toxic metals can find their way into crops, water, and fish

-May increase respiratory problems

- Dissolves calcium carbonate in concrete, marble, limestone, & monuments (ancient pyramids, Lincoln Memorial, etc.)

Problems with Acid Precipitation Control

• Pollutants are often released in an area far away from the area where acid precipitation falls.

• Ex: acid rain in SE Canada is a result of pollutants produced in NE United States.

Effects of Acid Precipitation – Ex: The Adirondack Mountains

A tree is weakened over time by acid rain, leaving it more susceptible to factors that would otherwise be harmless. Spruce and fir trees are so stressed by the acid pollution that they have succumbed to severe cold, drought, insect infestations or diseases. According to the U.S. Forest Service, death rates for many tree species have doubled or tripled in the last decade in the Adirondack Mountains.

Where is the acid rain?

1. Circle the areas with the most significant acid rain.

2. Draw an arrow to the sources of the sulfur dioxide.