Visibility in
our Nation's Parks and Wilderness Areas
Since 1988, the EPA, States, and Federal land management
agencies have conducted monitoring of air pollution and visibility impairment at a
number of national parks and wilderness areas across the United States.
IMPROVE
Visibility Monitoring Network
Access IMPROVE monitoring data resources and educational
material on the science of visibility and regulations.
By clicking on the map below, you can view the following information
for a specific park or wilderness area.
Photos:
representing clear, moderate and hazy conditions.
Air pollutants contributing to visibility
impairment.
Visibility Trends Graphs
expressing visibility in terms of the distance
you can see (visual range in miles) and in terms of deciview measurements
(a metric used in the regional haze rule).
Note: In these trend plots, visibility is evaluated by
looking at each 20% segment of monitor data taken at a site. Trends
presented here are in terms of the haziest ("worst") 20%,
middle 20%, and the clearest ("best") 20% of data. For
example the haziest ("worst") 20% represents the average
of the 20% haziest days for that monitor site.
