Air is made of different gases. A very important gas is oxygen because that is what we breathe, to live. Another gas in air is called ozone. Ozone is related to oxygen, but we cannot breathe it. Ozone is a tricky gas because it can be both bad and good for us, depending on where it is. Most ozone is many miles above the ground, where it covers the entire Earth like a blanket. We call that the ozone layer because ozone is just one part of the atmosphere, located in the stratosphere. It’s more than 10 miles, above the ground. Ozone is in the stratosphere is good because it blocks ultra-violet radiation coming from the sun. Ultra-violet radiation is what gives people sun tans. A lot of UV radiation over many years can cause skin cancers, and it can harm peoples’ eyes.
Scientists know that in certain times of the year, some of the ozone layer over the Arctic and Antarctic thins and disappears. They call this the Ozone Hole. Satellites measure ozone and show us where the thin spots are. The ozone hole mostly happens in places where not many people live but it worries scientists because they are not totally sure what makes the ozone disappear. Scientists do know that certain kinds of air pollution get in the way of ozone forming in the stratosphere. A lot of that pollution comes from gasses called chlorofluorocarbons or CFCs. Fortunately, many countries have stopped using CFCs.
Air pollution can actually increase ozone that forms near the ground, where we live. When ozone is near the ground, that is bad and unhealthy. It makes it harder for us to breathe. Older people, young children and people with breathing issues and asthma feel it first. Even some plants don’t grow well if ozone levels are high. A lot of ozone near the ground will even make your eyes dry and itchy. The pollution that makes ozone near the ground comes from factories, power plants, cars, trucks, buses, motorcycles, ships, and even gas lawn mowers. Some of the ingredients of gasoline, paints, and cleaners also play a role in forming ozone. It’s worse when weather is warm and sunny, and the winds are light, so that pollution mixes in the air and stays in place. When the sun goes down and the temperature is lower, ozone is not as bad, but it doesn't all disappear.
In big cities, ozone is even worse because there are more cars, more factories, and more people. Big cities are also warmer than small towns. All of that helps ozone form faster. When air quality is low you can sometimes see ozone and other pollution in the air, as haze. When ozone turns the sky yellow or brown, we call it smog. Smog is the words smoke and fog combined. Some of the air pollution rises into the clouds, where it mixes, to make even more pollution. When it rains, the raindrops carry the new pollution back to the ground and we call that acid rain. Acid rain can be toxic to slowly harm or kill trees and fish.
Remember that ozone in the stratosphere is natural and good because it protects us from ultra-violet radiation. Ozone near the ground is bad pollution. It makes it harder for some people to breathe.
Air pollution is part of what you see rising from smokestacks. Sometimes you’ll notice dust, ash, and other tiny things from smokestacks that fall onto the ground or onto cars. These little particles can make it harder for us to breathe because they go into our lungs and get in the way of oxygen. It is very hard for us to live without making ozone and air pollution by mistake. The best thing we can do to make our air cleaner and healthier is to conserve energy and not use as many fossil fuels. There are some fuels that make very little pollution. Three of them are a natural part of weather. They are solar power, water power, and wind power.