There has been a downward trend in the United States since 1980 in the ambient concentrations of
A)sulfur dioxide.
B)carbon monoxide.
C)lead.
D)all of the above.

Question

Quizplus · Accepted Answer

Since 1980, the United States has implemented various environmental policies and regulations to reduce air pollution. As a result, there has been a significant decrease in the ambient concentrations of sulfur dioxide, carbon monoxide, and lead. Therefore, D is the correct choice as it includes all three air pollutants.

There Has Been a Downward Trend in the United States