Ecosystem Region in United States

A pH of 5.6 is not a defensible value for defining the acidity level of "clean" or "pure" or "unpolluted" rain.

• The sensitive ecosystem region in the United States for which there is some reasonable documentation of damage to aquatic systems is largely confined to the Adirondacks area in New York and portions of New England.
• Large areas of the northeastern United States receive precipitation with an annual average pH ranging between 4.0 and 4.6.
• There is no evidence of increasing acidity in the precipitation falling on the Adirondacks. or New England over the last two decades.
• Lake chemistry is affected by a variety of factors -- with the natural acidity of soils and adjacent wetlands being important, perhaps the major source of acidity.
• Many lakes even in the absence of man made air pollution are undoubtedly inhospitable environments for sustaining fish populations.
• Fish restocking practices and fishing pressure must be taken into account when using fishing quality as an indicator of environmental influences.
• Fewer than 25 per cent of the sampled lakes in the ' Adirondacks are acidified (i.e., pH less than 5.0) and the rate of change is so slow (if at all) that it is questionable whether any changes-can be detected over the next decade or two.
• Alleged damage to forests by acid deposition, especially red spruce, is unverified at this time. Declines in forests seem to be tied to a drought which occurred during the late 1950's and early 1960's and/or to high levels of atmospheric ozone.
• Alleged impacts on agricultural crops and materials of construction are only hypothetical at the present and there is no scientific evidence supporting these claims.
• Alleged impacts on public health, especially the claim that sulfates cause 51,000 excess deaths per year are totally unsupported by credible scientific evidence and analyses.
• There is no evidence to support a conclusion that acid precipitation produces adverse health effects in drinking waters.
• Tall stacks do not have the effect on long-range transport once believed.
• Sulfur dioxide, oxides of nitrogen, and reactive hydrocarbons are all involved in the production of acid deposition.
•  The Northeast has a significant emission inventory of sulfur dioxide, oxides of nitrogen, and volatile organic compounds.
•  Emission densities are a better indicator of the potential for acid deposition formation than are absolute emission rates. Emission densities of these pollutants are about the same in the Northeast as in the Midwest.
•   The potential for production of oxidants is higher in the Northeast than in the Midwest suggesting that rapid transformation of precursors from sources in the Northeast to acid deposition in the Northeast is occurring.
•  Pathways by which precipitation and acidity arrive at points of concern are varied; less than half seems to arrive from the direction of the Midwest industrial region while more than half seems to be generated in the Northeast.
•  Wet deposition trends at Hubbard Brook in sulfate and nitrate are closely matched with emission trends of SO2 and NOx in the Northeast suggesting that sources in the Northeast may be controlling the chemical composition of wet acidic deposition falling in the Northeast and that emission sources in the Midwest play a relatively minor role.

The above conclusions seem to suggest that 

(1)We do not have an environmental crisis at our doorstep; 

(2)There is still a great deal that is unknown or only partially understood; 

(3)Additional research is warranted before additional emission control programs are instituted; 

(4)The present Clean Air Act will provide continuing protection to the environment while the research is being conducted; 

(5) The components of the popular theory are not securely founded on fact;

(6)An effective control program to protect the sensitive ecosystem areas in the Northeast must focus on controlling acid deposition sources of SO2, NOX , and volatile organic compounds in the Northeast.