Air quality - What has contributed to air pollution?
Our air gets dirty (polluted) when it starts to hold on to more tiny particles and the balance of the natural gases, that make air, change.
This started happening when man discovered fire but got worse at the beginning of the industrial revolution in the 18th century when humans started to develop industries and continues to this day. The invention of the car, burning fossil fuels and farming all contribute to increased levels of particles and gases.
The increase in particles can also be from natural sources like pollen and dust formed as a result of droughts or windy days in the desert, ash from volcanic eruptions and wildfires.
Air pollution is also caused by changing amounts of gases in the atmosphere. Many of these occur because of chemical reactions with other gases, sunlight or water vapour. One of these gases is called ozone, which is formed when sunlight reacts with chemicals that come from burning fossil fuels or vehicle exhaust fumes. When particles in the air combine with ozone, they create smog. Smog looks a bit like fog and makes it difficult to see.