Question

How and why have pollution levels in the United States changed over the past several decades?

A. The passage of the Clean Air Act Amendments of 1990 resulted in a decrease in the pH of rain in the midwestern and eastern United States
B. The passage of the Clean Air Act has resulted in current air pollution levels in the United States being much lower than they were in the 1960s
D. Despite the passage of the Clean Air Act, air pollution levels in the United States have continued to rise over the past 40 years
C. The passage of the Montreal Protocol resulted in a large increase in air pollution levels in the United States beginning in 1990

Answer 1

The passage of the Clean Air Act and subsequent amendments have resulted in a decrease in pollution levels in the United States over the past several decades.

Step-by-step explanation:

The pollution levels in the United States have changed over the past several decades due to the implementation of anti-pollution policies. The passage of the Clean Air Act in 1970 and subsequent amendments, such as the Clean Air Act Amendments of 1990, has resulted in a significant decrease in air pollution levels. These laws have required industries to meet stricter pollution standards, reduced vehicle emissions, and improved air quality in cities.

For example, the use of catalytic converters in vehicles and the requirement to switch to lead-free gasoline under the Clean Air Act led to a dramatic reduction in smog in American cities. Additionally, the adoption of technology in coal-fired power plants to scrub sulfur and other pollutants out of emissions streams has also contributed to the improvement of air quality.

Overall, the implementation of anti-pollution policies, like the Clean Air Act, has resulted in a decrease in pollution levels in the United States over the past several decades.