13.2. How do our activities affect the environment?

We are an integral part of the environment. Changes in the environment affect us and our activities change the environment around us. We have already seen in Class IX how our activities pollute the environment. In this chapter, we shall be looking at two of the environmental problems in detail, that is, depletion of the ozone layer and waste disposal.

Human activities are deeply intertwined with the environment. This means that whatever happens in the environment can have a direct impact on our lives. At the same time, the actions we take can also lead to changes in our surroundings. For instance, when factories release smoke into the air, it contributes to pollution, which deteriorates air quality and can lead to health problems for people living nearby. This section introduces the idea that we will explore significant environmental issues like the depletion of the ozone layer and the challenge of managing waste.

Think of the environment as a big web where each thread represents a connection between organisms and their surroundings. If one thread is pulled or torn, it can affect the entire web. When we throw away plastics or emit harmful gases, we pull on those threads, causing disruptions not just for us but for all living things.

Ozone (O₃) is a molecule formed by three atoms of oxygen. While O₂, which we normally refer to as oxygen, is essential for all aerobic forms of life. Ozone, is a deadly poison. However, at the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

The ozone layer consists of ozone molecules that absorb harmful ultraviolet (UV) radiation from the sun. This is crucial because UV rays can cause serious health issues like skin cancer and cataracts, as well as harming animals and plants. Without the ozone layer, life on Earth would be drastically affected, making it vital for our survival.

Imagine applying sunscreen before going out in the sun. The sunscreen protects your skin from harmful rays, just like the ozone layer protects us from UV radiation. If the sunscreen gets washed off or is too thin, you risk getting sunburned. Similarly, if the ozone layer is depleted, we are exposed to those harmful rays, leading to potential damage.

The amount of ozone in the atmosphere began to drop sharply in the 1980s. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers. In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels.

In the 1980s, scientists noticed a significant reduction in ozone levels, which was alarming because it indicated that the protective barrier around our planet was weakening. Investigations revealed that chemicals like CFCs, commonly found in fridges and aerosol sprays, were responsible for this depletion. In response, international agreements were made to reduce the production of these harmful substances, showing a global effort to tackle environmental issues.

It's like discovering that too many people are gathering in a small room and the air quality is declining. If we don't limit the number of people or improve ventilation (similar to reducing CFCs), the air will get stuffy and unhealthy. By controlling CFC production, countries are trying to 'ventilate' our atmosphere to keep it healthy.

In our daily activities, we generate a lot of material that are thrown away. What are some of these waste materials? What happens after we throw them away? Let us perform an activity to find answers to these questions.

As we go about our day, we produce various types of waste such as food scraps, packaging materials, and electronics. When we discard these materials, it is essential to understand what happens next. Some waste may decompose naturally and return to the soil, while others can remain in landfills for years, creating pollution problems. This section encourages students to be curious and investigate the lifecycle of their waste to understand its impact on the environment.

Think of your trash can as a mini-world. When you throw something away, it doesn't just disappear—it goes to a landfill (the trash can's equivalent of a big city). Some items will be recycled or decompose, while others can sit there for decades causing problems. Learning about our waste is like being detectives on a case—figuring out where each item goes after it leaves our hands.

Substances that are broken down by biological processes are said to be biodegradable. How many of the substances you buried were biodegradable? Substances that are not broken down in this manner are said to be non-biodegradable.

Biodegradable waste is made up of materials that can be broken down by microorganisms such as bacteria and fungi, returning nutrients to the environment. Examples include food scraps and paper. Non-biodegradable waste, on the other hand, does not break down easily and can pollute the environment, such as plastics and synthetic materials. Understanding the difference helps us make better choices about what to recycle and how to reduce waste.

Imagine a fruit. When you eat an apple, the leftover core decomposes and goes back into nature, enriching the soil. That's biodegradable! Now think of a plastic bottle—years later, it is still standing there, causing harm. This contrast helps us see why we should choose biodegradable options whenever possible.

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