Pollution is the introduction of harmful substances into the environment. It can be chemicals, particles, noise, light, or heat. Pollutants come from many sources: factories, vehicles, farms, homes, and waste sites. Some enter the air, some the water, some the soil. They harm organisms by poisoning them, disrupting their reproduction, or changing the conditions they need to survive. Pollution is one of the main drivers of biodiversity loss, alongside habitat destruction and climate change.

Pollution takes many forms. Air pollution from burning fossil fuels causes respiratory disease and acid rain. Water pollution from agricultural runoff and sewage creates algal blooms and dead zones. Plastic pollution chokes marine life and breaks down into microplastics that enter food chains. Light pollution disrupts the behavior of nocturnal animals and migrating birds. Noise pollution interferes with communication and navigation in whales and birds. Each type requires different solutions, from regulation to technology to changes in behavior.

Major types of pollution

• Air: particulates, nitrogen oxides, sulfur dioxide.
• Water: nutrients, chemicals, plastics, sewage.
• Soil: heavy metals, pesticides, industrial waste.
• Other: noise, light, and heat.

Pollution is not inevitable. It is a byproduct of how we produce and consume. Cleaner technologies and stricter rules have reduced some forms of pollution, but progress is uneven.