Ozone pollution
Average seasonal population-weighted ozone levels (parts per billion).
0 ppb
5 ppb
10 ppb
15 ppb
20 ppb
25 ppb
30 ppb
35 ppb
40 ppb
45 ppb
50 ppb
55 ppb
60 ppb
65 ppb
70 ppb
75 ppb
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
China
India
United States
China
India
United States
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