Cleaning Big Cities’ Air “Not Rocket Science,” Expert Says

Hemmed in by mountains on three sides, the basin that houses Mexico City, Mexico, has some the dirtiest air in the world.

Pollutants spewed by power plants and tailpipes have nowhere to go. They stay within the city and compromise the health of thousands of people.

But it doesn’t have to be this way, according to Mario Molina, a Nobel laureate in chemistry who is affiliated with the Massachusetts Institute of Technology in Cambridge and the University of California, San Diego.