See the context of this sign.

Diminishing View

On a clear day Mt. Trumbull is
visible on the distant horizon 60
miles to the west. How well can
you see Mt. Trumbull today?

Visitors to the Grand Canyon
usually expect panoramic views in
clean desert air. But air pollutants
drastically impair visibility at Grand
Canyon National Park. Clear days
allow views approaching 100 miles.
On other days air pollution reduces
visibility to 18 miles or less.

The use of modern emission control
equipment on existing pllution
sources and careful placement of
new industry can help restore Grand
Canyon views. We can all play a part
by conserving electricity, carpooling,
recycling, becoming involved in air
quality issues, and supporting local
and national policies that recognize
the importance of clean air.

Pollution Sources
Air pollution at Grand Canyon comes
from both local and distant sources
Weather patterns dictate how the
contributions of each source changes
over time.

In summer, pollutants often travel
great distances from industrial and
urban areas of southern California,
southern Arizona, and northern
Mexico. In winter, local sources
and sources in southern Arizona
are usually the main contributors.

Don't miss the rest of our virtual tour of Grand Canyon National Park in 10803 images.