The study looked at how where people live and what cars they drive affects air pollution in Montreal. They found that people who drive older, bigger cars create more pollution, but often live in less polluted areas. On the other hand, people who drive less or use alternative modes of transportation tend to live in more polluted areas. The researchers also discovered that living in walkable neighborhoods with lots of shops can lead to higher exposure to pollution. This shows that there are big differences in how much pollution people create and how much they are exposed to.