Several articles and links are presented here to further your understanding of air pollution causes and effects, air quality monitoring goals and methodologies, and visibility as it relates to the management of visual resources in and near federal lands.
These include:

ABOUT USDA-FS AIR PROGRAM.
CAUSES OF POOR VISIBILITY.
INTERPRETING VISIBILITY DATA.
FLMS VISIBILITY OVERVIEW
INTRO TO VISIBILITY.

Specific articles can be accessed using the drop-down Further Information menu.

Access to other sites and articles of interest are also provided under the Links feature above.