Answer :

Compared with 1970, the emissions of the five primary pollutants in the united states in 2011 have been significantly reduced.

Since the Clean Air Act of 1970, the USA has decreased emissions of every of the six monitored pollution substantially. In the U.S., the EPA and the states reveal out of doors air high-satisfactory through measuring concentrations of the 6 standards pollution. Outdoor air these days is a ways higher than a era or ago.

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