Visibility Reduced visibility in the western United States is a concern. The Clean Air Act requires visibility protection for National Parks and Wilderness Areas, but has not issued guidelines for other areas. Smog and particulate matter are the main pollutants which reduce visibility. Regional haze itself does not impair health, although the pollutant causing the reduced visibility may have health implications. However, there are indirect economic impacts associated with haze.
People perceive haze as the most obvious indication that there is an air pollution problem.
The scenic image of Idaho could be harmed if smog and haze become common. Since tourism and travel is Idaho s third largest industry, clean air is important to the state s economy. Acid Rain Acid rain occurs when pollution such as sulfur dioxide or nitrogen oxides mix with moisture in the atmosphere and increase the acidity of normal precipitation. Acid rain or snow can injure vegetation and crops, erode buildings, and damage lakes and streams. In extreme cases bodies of water become so acidic that fish and other organisms are unable to survive.