Nationally, only automobiles produce more ozone forming emissions (oxides of nitrogen) than power plants. Research is increasingly linking ozone pollution to the development of asthma in children. Ozone may also be related to premature birth, cardiac birth defects, low birth weight and stunted lung growth. Children and the elderly are most sensitive to this pollution. Ozone pollution is also responsible for decreased visibility, lower agricultural yields and negatively impacts overall tree and plant health.