Time that could be spent exercising and decreasing stress is instead spent behind the wheel, raising your blood pressure and increasing stress. Time you spend in traffic is time that could be spent with your family. Your quality of life. Polluted air contributes to many cases of asthma, especially in inner cities. Polluted water raises filtration costs and taxes due to the affect on animals such as salmon.
Paved land replaces parks or reserves and eliminates homes for wildlife.
Live close to work. This sounds strange, but living close to your job is one of the best ways to reduce your commute and help the traffic problem. Some people have real reasons for which they cannot choose where they live or work, but most don't. The next time you change jobs or locations, think about how you are going to get to work. Use pollution-reducing transit for commuting and travel.