Question

mexico city is surrounded by mountains. what effect has this had on the air quality in this city?

Answer 1

Check the last sentence in the fifth paragraph.

http://encarta.msn.com/encyclopedia_761569238/mexico_city.html

This site may also help you.

http://visibleearth.nasa.gov/view_rec.php?id=3419

Answer 2

Because I wanted the effect of it