Over the past 20 years, the efforts of the united states have decreased the amount of pollutants in the environment.

True - In the past twenty years, the EPA has actively worked with state and national governments to implement environmental laws to help reduce toxic emissions from automobiles and the industrial sector. Companies are being held accountable for air emissions, land waste and water pollutants, they are being made to not only pay fines, but to clean up polluted areas while developing better techniques which will reduce the amount of toxins released. We now have an increased use of renewable energy such as solar panels, windmills and hydroelectricity.