We all know air pollution is a prominent issue in many countries across the world. But why does it seem to keep getting worse?
Non-excludable, yet rivalrous
One reason air pollution is so bad is that clean air is a common access resource, or common pool resource. Common pool resources are resources that are non-excludable yet rivalrous. Non-excludable means anyone can use it and no one can prevent others from using it. Rivalrous means one person's usage reduces the quality and availability for others.
Another example is shared Wi-Fi in cafes. When lots of people are using it — or one person is playing a high-definition video game — the internet slows down for everyone else on the network. Everyone can connect, but one person's use reduces the quality for others.
Self-interest meets shared air
Back to air pollution: unless there are restrictions, people and firms can't be stopped from polluting the air, because it's non-excludable. Since individuals generally act on their own self-interest (part of rational consumer behavior), they don't consider the impact of their actions on others — and they keep polluting. Their pollution degrades air quality for everyone else, which is why this resource is rivalrous.
The takeaway
Common pool resources tend to be overused, leading to consequences like environmental damage, societal harm and — as we've learned — pollution.