The EPA sets national air-quality standards for common air pollutants. The
data table shows the change in concentrations of these pollutants over time.
Emissions Reductions and Air Quality
Data period
Reduction
Pollutant
Improvement
(from/to)
in emissions (%) in air quality (%)
СО
69
85
Pb
99
98
1980 - 2014 NO,
55
60
0,
53
33
81
80
16
30
2000 - 2014
33
36
SO2
PM,
PM25
Which conclusion do the data support?