Saul Mandel (1926 - 2011) "Earth Day - Clean Air" Signed lower right. Original Watercolor painting. Provenance: Collection of James A. Helzer (1946-2008), Founder of Unicover Corporation. This painting originally appeared on the Fleetwood First Day Cover of the 32c Tree Planting stamp issued April 20, 1995. Polluted air has existed in urban communities for many years. Concern about this condition is a relatively recent development. As we become more aware of the harmful effects of poor air quality on living things, increased efforts are being made to find ways to eliminate or control its causes. For example, scientific studies have proven that when waste gases, such as those released by the burning of fossil fuels in electric power plants and refineries, combine with atmospheric water vapor, certain types of acids are formed and ultimately fall to the ground. This condition, known as "acid rain", can lead to detrimental effects on the ecology. Acidic precipitation has been found to be harmful to trees and other forms of vegetation, resulting in foliage damage and reduction in growth. More obvious signs of air pollution are noted in large urban centers such as Los Angeles, where the brown haze known as "smog" hangs over the city. Another damaging side effect is caused by automobile exhaust. When these noxious gases are released into the air, their presence can cause respiratory distress as well as damage to plant life. The enforcement of auto emissions testing and tighter controls on industry have begun to improve the life-giving air we breathe. Image Size: 9.75 x 8 in. Overall Size: 13.75 x 11 in. Unframed. (B14985)