New research shows that when air pollution goes down in a city, people’s health can improve quickly. In Greece, scientists studied what happened after fewer polluting vehicles were on the roads and less coal was burned for electricity. They found that cleaner air helped the local community become healthier in a short time.

This happened because air pollution from cars and coal contains tiny particles and gases. These can enter people’s lungs and cause health problems, such as heart and lung diseases. When pollution levels fall, people have less risk of these illnesses.

As a result, people nearby had fewer health problems linked to pollution, and hospitals had less pressure. This means that making the air cleaner is not just good for the environment in the future—it can help people living in cities right now.