42 USC 8901 - Introductory provisions

(a) Congressional statement of findings and purpose 
The Congress finds and declares that acid precipitation resulting from other than natural sources
(1) could contribute to the increasing pollution of natural and man-made water systems;
(2) could adversely affect agricultural and forest crops;
(3) could adversely affect fish and wildlife and natural ecosystems generally;
(4) could contribute to corrosion of metals, wood, paint, and masonry used in construction and ornamentation of buildings and public monuments;
(5) could adversely affect public health and welfare; and
(6) could affect areas distant from sources and thus involve issues of national and international policy.
(b) Congressional declaration of purpose 
The Congress declares that it is the purpose of this subchapter
(1) to identify the causes and sources of acid precipitation;
(2) to evaluate the environmental, social, and economic effects of acid precipitation; and
(3) based on the results of the research program established by this subchapter and to the extent consistent with existing law, to take action to the extent necessary and practicable
(A)  to limit or eliminate the identified emissions which are sources of acid precipitation, and
(B)  to remedy or otherwise ameliorate the harmful effects which may result from acid precipitation.
(c) “Acid precipitation” defined 
For purposes of this subchapter the term acid precipitation means the wet or dry deposition from the atmosphere of acid chemical compounds.