Trees Make the Air Cleaner

Trees absorb carbon dioxide during photosynthesis, and release oxygen, which is essential for human and animal life. One mature tree can absorb around 22 kg of carbon dioxide per year on average (as an example).

Forests act as massive carbon sinks, storing carbon in their trunks, branches, leaves, and soil for decades or even centuries. Globally, forests absorb nearly 16 billion metric tonnes of carbon dioxide per year and hold approximately 861 gigatonnes of carbon in their ecosystems.

Air pollutant particles from ash, dust, smoke, etc. stick to leaf surfaces instead of staying in the air. When it rains, the particles are washed off the leaves into the soil, and are broken down by microbes, permanently removing them from the air.

Additionally, trees can “eat” pollution through tiny pores (stomata) on their leaves, absorbing gases directly into their internal tissues, not just trapping them on the surface.

Trees may be planted in areas where air pollutants are most prominent. Trees on streets are not only an aesthetic feature, but they can protect our health by filtering out air pollutants between traffic and people, and can reduce nearby air pollution by up to 60%.

Species with rough, hairy, or waxy leaves (like pine or silver birch) capture much more pollution than smooth-leaved trees.

Trees reduce pollution indirectly by lowering energy use: cooler streets mean less air conditioning, which means fewer emissions from power stations.

Mature trees store more carbon, but fast-growing young trees often absorb pollution more aggressively.

As part of the "Great Green Wall" project in China, so many trees have been planted around the Taklamakan Desert,one of the world's largest and driest deserts, that it has turned what was once considered a "biological void" into a carbon sink that absorbs more carbon dioxide than it emits. The project aims to plant billions of trees around the margins of the Taklamakan and Gobi deserts by 2050! (Live Science)