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10 

 particularly regional haze, "despite major advances in monitoring 



techniques, regional scale models, and scientific knowledge " 



The NRC Report also finds that other Clean Air Act programs "will 

 not solve the nation's visibility problem." In fact, despite the 

 1990 Clean Air Act Amendments, the NRC Report states that sulfur 

 dioxide emissions — a major cause of visibility impairment — are 

 likely to increase through 2010 in the West, where the visibility 

 resource is particularly valuable and vulnerable. EPA has recently 

 provided its own projection in an October 1993, report to Congress. 

 Having modeled estimates of emission changes through 2005 affected 

 by the implementation of the 1990 Clean Air Act Amendments, EPA 

 concludes that the visibility in the Class I areas of the rural 

 Southwest will not change perceptibly. 



The NRC Report includes the following excellent recommendations: 



o To make progress toward the Clean Air Act's visibility 

 protection goal "will require regional programs that 

 operate over large geographic areas and limit emissions 

 of pollutants that can cause regional haze." 



o These programs should "consider many sources 

 simultaneously on a regional basis." Although 

 determining the contribution of individual sources may be 

 helpful in certain circumstances (such as assessing the 

 impacts of a proposed major new source) , the NRC Report 



