About oxygen

You can probably hold your breath for a short time. But after just a few moments, you start breathing again. When we breathe, we draw air into our lungs. Most of the air we breathe in consists of a gas called nitrogen. The air also contains a gas called oxygen, which is essential for life. The lungs consist of two lobes, arranged like an upside-down tree. At the ends of increasingly narrow tubes are tiny air sacs. In these air sacs, red blood cells absorb oxygen from the air. They then carry it wherever it is needed, especially to the brain, organs and muscles. There, energy is produced, enabling us to think, digest food and move. This process produces carbon dioxide, which the red blood cells then carry back to the air sacs. From there, it passes into the air we breathe out.

Oxygen is produced by plants, especially trees. Trees grow with the help of sunlight, water and minerals from the soil. They also absorb carbon dioxide gas from the air. Here’s how: the leaves and needles of trees are made up of tiny cells. Inside each cell are small compartments called chloroplasts. These chloroplasts contain a green pigment called chlorophyll.

With the help of sunlight, chlorophyll produces glucose from carbon dioxide and water. This glucose serves as a building block for new cells that allow the tree to grow. Oxygen is released in this process and given off by the trees into the environment. For example, a mature beech tree produces around 1.7 kilograms of oxygen per hour—enough to meet the needs of about 50 people for an hour.

Oxygen is used not only by people and other living things. Plants can only rot when oxygen is present. Iron rusts when it comes into contact with oxygen. A candle flame and a fire need oxygen to burn. However, when we burn wood, coal, gas or oil, carbon dioxide is produced. Because we have burned a great deal of it over the past 200 years, there is more and more carbon dioxide. This gas rises into the air. At high altitudes, it lets the Sun’s rays pass through to Earth, but in turn, it traps heat in the Earth’s atmosphere. As a result, our planet is gradually getting warmer and the climate is changing. That is why it is so important to care for our trees and forests, which not only produce oxygen but also reduce carbon dioxide.