1. An interruption in the intensity or the amount of something: There was finally an abatement of the violence in the attacks by the enemy forces.
2. Diminution in amount, degree, or intensity: The loud talking by the couple in the next room at the hotel came to an abatement when Mrs. Donald in the neighboring room knocked on the wall.
3. The amount lowered; a reduction: The store offered customers abatements of their products after the Christmas season.
4. A diminution, a decrease or an easing: In medicine there may be an abatement of pain or any other symptom or sign of a physical ailment.

In the environment there may be abatements in the degree of pollution over various periods of time.