What action can the EPA take under the Clean Air Act regarding mercury emissions from power plants?

The action that the Environmental Protection Agency (EPA) can take under the Clean Air Act regarding mercury emissions from power plants, specifically requiring a 90% reduction in those emissions, reflects the agency's mandate to regulate pollutants that can harm public health and the environment. Mercury is a toxic heavy metal that can cause significant health issues, especially in vulnerable populations such as pregnant women and young children.

Under the Clean Air Act, the EPA has the authority to set National Ambient Air Quality Standards and to list specific hazardous air pollutants, including mercury. Through regulations like the Mercury and Air Toxics Standards (MATS), the EPA can enforce strict guidelines for power plants to implement technologies and practices that lead to substantial reductions in mercury emissions. A target of a 90% reduction is both ambitious and necessary to significantly minimize the risks associated with mercury exposure.

This regulatory framework supports the EPA’s broader goals of improving air quality and protecting human health, which aligns directly with the chosen answer regarding the substantial reduction of mercury emissions from power plants.