Asthma is rapidly becoming one of the major health issues in the United States, especially for children living in cities. A study released by the National Institute of Allergy and Infectious Diseases in 2008 showed that asthma particularly affected children in poor, inner-city areas and that car emissions of nitrogen dioxide, as well as air particulates and sulfur dioxide, were to blame. The study evaluated over 800 children in seven urban areas. These children had significantly higher rates of asthma and decreased lung function, which contributed to poor health and school absenteeism, even when the level of pollutants in the areas where they lived was deemed to be lower than acceptable standards set by the Environmental Protection Agency. Other studies have also shown that children have more allergies when they have been exposed to higher levels of air pollution.