Air Quality

The Grand Canyon lies downwind from coal-fired power plants in the Four Corners region, local mining operations, and urban and industrial regions of Mexico and California that all send pollution wafting overhead. The resulting effect on visibility at the canyon can be quite dramatic, not to mention the harm that pollution causes to the park's forests, soil, waterways, and wildlife. The impact that most park visitors may notice is on the views, which can be reduced from 170 miles to about below 70 miles by hazy pollution. Crystal-clear days are rare; on most days, pollution reduced canyon visibility to about 120 miles. Webcams within the park monitor daily visibility, while the National Park Services uses other instruments to track ozone, nitrogen, and sulfur levels. Shuttle buses and alternative-fuel vehicles are used in part to reduce automobile pollution in the park.