The Clean Air Act was principally concerned with ______.

• A. Water quality
• B. Indoor air quality
• C. Automobile and factory emissions
• D. Noise pollution

Answer: (C)

The main idea behind the Clean Air Act is to reduce outdoor air pollution by limiting what vehicles and industrial sources release into the atmosphere. It sets standards for pollutants such as ozone, particulate matter, sulfur dioxide, and nitrogen oxides, and it requires controls on emissions from cars, trucks, and factories, along with state plans to meet those standards. That focus on outdoor air and emissions from mobile and stationary sources is why automobile and factory emissions is the best fit. Water quality is handled by the Clean Water Act, indoor air quality by workplace and building standards rather than the core air pollution law, and noise pollution is governed by different statutes.