Impact on the Atmosphere Chapter Notes | Science for Grade 5 PDF Download

Introduction

This chapter, "Impact on the Atmosphere," explores how human activities and natural events affect Earth's atmosphere. It explains different types of air pollution, their causes, and their effects on the environment and human health. The chapter also discusses solutions, such as vertical forests and renewable energy, that help protect the atmosphere. By learning about these topics, students will understand the importance of keeping the air clean and how everyone can contribute to reducing pollution.

What is air pollution?

• Air pollution is when harmful substances, like gases and smoke, mix with the air.
• It happens because of human activities, such as using energy for homes, vehicles, and electricity.
• Growing human populations increase energy use, which leads to more air pollution.
• Types of air pollution include smog, chlorofluorocarbons (CFCs), particulate matter, and acid precipitation.

Photochemical Smog

• Photochemical smog is a brownish haze in the air caused by sunlight reacting with nitrogen and carbon compounds.
• These compounds come from burning fossil fuels in vehicles and power plants.
• The reaction forms ozone near the ground, which makes breathing difficult.
• Ground-level ozone can harm plants and animals by damaging their tissues.
• Ozone in the upper atmosphere (ozone layer) protects life by blocking harmful ultraviolet (UV) rays from the Sun.

Chlorofluorocarbons (CFCs)

• CFCs are chemicals released from old refrigerators, air conditioners, and aerosol cans.
• They are entirely caused by human activities.
• CFCs react with sunlight in the upper atmosphere and destroy ozone molecules.
• This thins the ozone layer, allowing more UV rays to reach Earth.
• Increased UV rays can harm the tissues of plants and animals.
• In the 1970s, scientists found that CFCs were thinning the ozone layer, especially over Antarctica.

Particulate Matter

• Particulate matter is a mix of solid and liquid particles in the air, like smoke, dust, and dirt.
• It comes from natural events like volcanic eruptions and forest fires.
• Human activities, such as burning fossil fuels in power plants and vehicles, also release particulate matter.
• Breathing in these particles can cause health problems like asthma, bronchitis, and heart attacks.
• Particulate matter can also disrupt plant processes like cellular respiration and photosynthesis.

Acid Precipitation

• Acid precipitation is rain or snow with a lower pH than normal rainwater (normal pH is about 5.6).
• It forms when nitrogen and sulfur gases mix with water, oxygen, and other chemicals in the air.
• These gases come from burning fossil fuels and, to a lesser extent, from volcanoes and marshes.
• Acid rain harms soil, trees, and plants by making the environment too acidic.
• It can also hurt fish and other organisms in lakes and rivers by lowering the water’s pH.
• Living things struggle to survive if the pH of water or soil becomes too low.

A Closer Look: Air Pollution and Health Effects

• Breathing clean air is important because the body uses oxygen to produce energy.
• Polluted air can harm the body and cause diseases like pneumonia, emphysema, and bronchitis.
• Air pollution can trigger asthma, a condition where breathing passages narrow, making it hard to breathe.
• Doctors use inhalers to help people with asthma breathe better by relaxing airways.
• Over 1.3 billion people live in areas with dangerously polluted outdoor air, according to the United Nations.
• In urban areas, asthma cases have increased, with over 7% of children affected today.

How can we protect the atmosphere?

• Protecting Earth's atmosphere requires joint efforts from government leaders, scientists, and the public.
• Countries across the globe are working together to reduce air pollution.
• One major step is the Montreal Protocol, an international treaty signed by 197 countries, including the United States, aimed at phasing out harmful CFCs (chlorofluorocarbons).
• In the U.S., the Clean Air Act sets legal limits on how much of certain pollutants can be released into the air.
• Some states, like California, have created their own vehicle emission standards to control air pollution.
• At least twelve other states have either adopted or plan to adopt similar standards to further reduce air pollution.

Positive Actions

• International, national, and state laws help monitor and reduce harm to the atmosphere.
• Individuals can also make a positive impact through their daily actions.
• Simple actions like turning off lights when leaving a room help reduce environmental impact.
• People can contribute by educating others about environmental issues.
• Making thoughtful decisions as a consumer also supports environmental protection.
• Additional helpful suggestions will be shared to encourage more positive environmental choices.

Making a Difference

• There are many ways people can help reduce air pollution.
• Even without owning a car or house, individuals can make a difference by planting trees to improve air quality.
• Turning off lights and electronics when not in use helps conserve energy.
• Choosing to walk, bike, or use public transportation also helps reduce energy use.
• Recycling materials like metal, paper, plastic, and glass lowers the fuel needed to produce new items, reducing pollution.
• Reducing both direct and indirect energy use leads to fewer air pollutants being released.
• People can invest in energy-efficient technologies, such as hybrid vehicles that run on both fuel and battery power.
• Electric cars use only electric energy, producing less pollution.
• Another solution is using renewable energy sources like solar, wind, and geothermal power to heat homes and generate electricity.
• Renewable resources can be replaced naturally in a short time, making them a cleaner and more sustainable option.