What would expect to happen to someone's total lung capacity if they lived in an environment with a lot of air pollution such as smog, coal dust, tobacco smoke etc?

Lung capacity would not change. air filtration would be majority affected but capacity would not change

Depression is lifelong, though you can get medication to with it. the difference between sadness and depression is that sadness lasts a little bit, depression last a long time and it goes on and off. people usually get depression through experiences they have been through, or genetics.