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Learn about why the atmosphere is crucial, the impacts of air pollution, pollutants from vehicle exhaust, and acid precipitation effects. Discover measures of air quality.
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Unit 4Lesson 3 Human Impact on the Atmosphere Air: What Is It Good For? Why is the atmosphere important? • Air is an important natural resource. • The air you breathe forms part of Earth’s atmosphere. • Theatmosphere is a mixture of gases that surrounds Earth.
Unit 4Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? • The atmosphere provides gases that organisms need to survive, including oxygen and carbon dioxide. • The atmosphere blocks harmful, high-energy radiation coming from space. • Fast-moving particles, called cosmic rays, enter the atmosphere every second. They collide with various gas molecules and are slowed down.
Unit 4Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? • A part of the atmosphere called the stratosphere contains ozone gas (O₃). • The ozone layer absorbs most of the high-energy radiation from the sun, called ultraviolet radiation(UV), that reaches Earth.
Unit 4Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? • Without the atmosphere, temperatures on Earth would not be stable, and it would be too cold for life to exist. • The greenhouse effect is the way by which certain gases in the atmosphere, such as water vapor and carbon dioxide, absorb and reradiate thermal energy. • Carbon dioxide and water vapor are called greenhouse gases.
Unit 4Lesson 3 Human Impact on the Atmosphere What is air pollution? • The contamination of the atmosphere by pollutants from human and natural sources is called air pollution. • Air pollution can come from natural sources, such as volcanic eruptions, wildfires, and dust storms. • In cities and suburbs, most air pollution comes from the burning of fossil fuels.
Unit 4Lesson 3 Human Impact on the Atmosphere What is air pollution? • Some air pollutants are classified as gases, such as carbon monoxide, sulfur dioxide, nitrogen oxide, and ground-level ozone. • Other air pollutants are classified as particulates. A particulate is a tiny solid particle that is suspended in air or water. • The particulates from vehicle exhaust are a major cause of air pollution in cities.
Unit 4Lesson 3 Human Impact on the Atmosphere It Stinks! What pollutants can form from vehicle exhaust? • Vehicle exhaust is a common source of air pollution in urban areas. • Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air. • Although ozone in the ozone layer is necessary for life, ground-level ozone can damage the lungs.
Unit 4Lesson 3 Human Impact on the Atmosphere What pollutants can form from vehicle exhaust? • Smog is another type of pollutant formed from vehicle exhaust. • Smogforms when ground-level ozone and vehicle exhaust react in the presence of sunlight. • Smog can cause lung damage and irritate the eyes and nose. In some cities, there is enough smog to make a brownish haze over the city.
Unit 4Lesson 3 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? • Precipitation such as rain, sleet, or snow that contains acids from air pollution is called acid precipitation. • Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air. • When these gases mix with water in the atmosphere, they form sulfuric acid and nitric acid.
Unit 4Lesson 3 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? • Sulfuric acid and nitric acid are strong acids. They can make precipitation so acidic that it is harmful to the environment.
Unit 4Lesson 3 Human Impact on the Atmosphere What are some effects of acid precipitation? • Acid precipitation can cause soil and water to become more acidic than normal. • An increase in soil acidity can cause the soil to lose some of the nutrients that plants need. • Bacteria and fungi in the soil are also harmed by acidic conditions.
Unit 4Lesson 3 Human Impact on the Atmosphere What are some effects of acid precipitation? • Acid precipitation can also make lakes and streams more acidic and cause soils to release toxic metals into the water. • These changes can harm aquatic organisms, disrupt habitats, and decrease the biodiversity of an ecosystem. • Acid precipitation can also erode the stonework on buildings and statues.
Unit 4Lesson 3 Human Impact on the Atmosphere How’s the Air? What are measures of air quality? • Measuring how clean or polluted the air is tells us about air quality. • As pollution increases, air quality decreases. • Two major threats to air quality are vehicle exhausts and industrial pollutants.
Unit 4Lesson 3 Human Impact on the Atmosphere What are measures of air quality? • The Air Quality Index (AQI) is a number used to describe the air quality of a location. • The higher the AQI number, the more people are likely to have health problems linked to air pollution. • The air inside a building can become more polluted than the air outside. Ventilation, or the mixing of indoor and outside air, can reduce indoor air pollution.
Unit 4Lesson 3 Human Impact on the Atmosphere What are measures of air quality? • What are some sources of indoor air pollution?
Unit 4Lesson 3 Human Impact on the Atmosphere How can air quality affect health? • Daily exposure to small amounts of air pollution can cause serious health problems. • Children, elderly people, and people with health problems are especially vulnerable to the effects of air pollution. • Short-term effects include coughing, headaches, and wheezing. Long-term effects include lung cancer and emphysema, which can cause death.
Unit 4Lesson 3 Human Impact on the Atmosphere Things are Changing How might humans be changing Earth’s climates? • As a result of burning fossil fuels, the atmosphere today contains about 37 percent more carbon dioxide than it did in the mid-1700s. • Average global temperatures have also risen in recent decades.
Unit 4Lesson 3 Human Impact on the Atmosphere How might humans be changing Earth’s climate? • It is hard to know exactly how much the extra greenhouse gases change the temperature. • Computer models designed to understand climate change predict that average global temperatures will continue rising.
Unit 4Lesson 3 Human Impact on the Atmosphere What are some predicted effects of climate change? • Many changes on Earth have already been linked to higher temperatures. • A warmer Earth may lead to changes in rainfall patterns, rising sea levels, and more severe storms. • Such changes will likely have negative effects for life on Earth, as well as political and economic effects.
Unit 4Lesson 3 Human Impact on the Atmosphere How is the ozone layer affected by air pollution? • Earth’s protective ozone layer is thinning over the polar regions, allowing more harmful ultraviolet radiation to reach Earth’s surface. • Chemicals called chlorofluorocarbons (CFCs) cause ozone to break down. CFCs once had many industrial uses, but now they are banned. • However, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone.
