From the NYTimes:
Exhaust from cars and trucks exacerbates asthma in children and may cause new respiratory illnesses and heart problems in adults, even resulting in deaths.
The meta-analysis included 700 peer-reviewed studies on varying aspects of motor vehicle emissions and health. It found “evidence of a causal relationship,” but not proof of one, between pollution from vehicles and impaired lung function and accelerated hardening of the arteries.
The study found that the biggest effects occurred among people who lived within 300 to 500 meters — about two-tenths to three-tenths of a mile — from highways and major roads. That applies to 30-40% of the population of North America.
“Like the issue of second-hand smoke, it’s very difficult to understand the exact mechanisms that make it bad — but it’s easy to understand that it is in fact bad.”
Report Links Vehicle Exhaust to Health Problems. NYT, 2010.