Pollution happens when harmful or unwanted substances get released into the environment, making the air, water, or land dirty or unsafe. When a factory releases smoke into the sky, chemicals into a river, or trash onto the ground, it's creating pollution.

There are many types of pollution. Air pollution comes from car exhaust, factory smokestacks, and burning coal, making the air harder to breathe and contributing to climate change. Water pollution occurs when sewage, oil spills, or chemicals contaminate lakes, rivers, and oceans, harming fish and other wildlife. Plastic pollution happens when bottles, bags, and other plastic waste end up in nature instead of being recycled or properly disposed of.

Pollution affects everyone. Cities with heavy air pollution have hazy skies and higher rates of asthma. Rivers fouled by pollution can't support healthy fish populations. Ocean pollution threatens sea turtles and seabirds that mistake plastic for food.

The word can also describe other kinds of contamination. Noise pollution refers to constant loud sounds that disturb peace and quiet, like traffic noise or construction. Light pollution describes excessive artificial light that makes it hard to see stars at night.

Fighting pollution involves many efforts: people reducing waste, companies changing how they manufacture products, and governments creating laws to protect clean air and water.