The epa sets national air-quality standards for common air pollutants. the
graph shows the change in the concentrations of these pollutants over time.
which pollutant have the air-quality standards had the greatest impact on?
monitored concentrations
of pollutants
1.00
pm 25
0.70
normalized concentration
ozone
pm 10
0.50
0.40
noz
so2
0.30
0.20
0.10
co
lead
0.0
1980 1985 1990 1995 2000 2005 2010
year
o a no
b. lead
o
c. ozone
o
d. pm10