(2) Andrew Dunn.http://en.wikipedia.org/wiki/Image:LondonSmog.jpg.
CC-BY-SA 2.0.(3) http://en.wikipedia.org/wiki/File:Acid_rain_woods1.JPG. CC-BY-SA.(4) EPA.http://en.wikipedia.org/wiki/Image:Origins.gif. Public Domain.(5) EPA.http://en.wikipedia.org/wiki/Image:
US-overall-nonattainment-2007-06.png. Public Domain.(6) http://en.wikipedia.org/wiki/Image:Pollution_-_Damaged_by_acid_rain.jpg.
GNU-FDL.(7) Jami Dwyer.http://en.wikipedia.org/wiki/Image:Lacanja_burn.JPG. Public
Domain.(8) NPS.http://en.wikipedia.org/wiki/Image:Air_.pollution_1.jpg. Public
Domain.(9) Jet contrails block sunlight.. GNU-FDL.(10) David Iliff.http://en.wikipedia.org/wiki/Image:Los_Angeles_Pollution.jpg.
CC-BY-SA 3.0.
(11) http://en.wikipedia.org/wiki/Image:DodgeCatCon.jpg. Public Domain.
(12) Smog in New York City.. Public Domain.
(13) NASA.
http://en.wikipedia.org/wiki/Image:160658main2_OZONE_large_350.png.
Public Domain.
(14) EPA.http://en.wikipedia.org/wiki/Image:Bafflespray.jpg. Public Domain.
(15) http://commons.wikimedia.org/wiki/File:FCX_Clarity.jpg. GNU-FDL.
