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Technology Transfer Network - OAR Policy and Guidance

OAR Policy and Guidance Metarecord

Document Title/Subject:
Visibility in Mandatory Federal Class I Areas (1994-1998): A Report to Congress : Fact Sheet
Related Documents:
Signed by: Unsigned

Signature Date:

Gary Blais



Regulatory Authority:
Title 1
Air Quality Strategies and Standards Division (OAQPS) / Lydia Wegman
Submitted By:
OGC Contact:
Mike Prosper
OGC Phone#:
Internet Contact:
Jeff Clark
Document Type:
Fact Sheets
EPA Document Number:

Federal Register:
Subject Category:
Particulate matter
Visibility Regional Haze Class I Areas National Parks
Air quality
Clean Air Act
This Report to Congress on visibility is an assessment of actual progress and improvement in visibility conditions in mandatory national parks and wilderness areas valued for their scenic views. These areas are known as Federal Class I areas. Under section 169 of the Clean Air Act (CAA; as amended in 1990), the Environmental Protection Agency (EPA) must issue a report to Congress estimating the visibility improvement that could be expected in Class I areas due to implementation of the 1990 CAA Amendments. The EPA first issued this report in October 1993. The CAA also requires that every 5 years thereafter, EPA shall provide Congress with an assessment of actual progress and improvement in visibility in Class I areas in the form of a written report with copies to appropriate Congressional committees. This report is intended to satisfy that requirement and assesses visibility improvement over the period 1994-1998. Visibility conditions at forty-three monitor locations were calculated based on particulate matter concentrations for the period from 1994 through 1998. Visibility conditions showed statistically significant improvements at six sites on the least-impaired days and five sites on the most-impaired days. They also showed declines at three sites on the least-impaired days but no sites on the most-impaired days. This file is a fact sheet summarizing the report.

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