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NEW YORK (Reuters Health) - Children who live in neighborhoods plagued by violence may have a higher risk of asthma than those who grow up in more peaceful surroundings, a new study hints.Researchers found that among more than 2,000 Chicago children age 9 or younger, those from neighborhoods with moderate to serious problems with violence were about 60 percent more likely to develop asthma in the next few years than children from less violent neighborhoods. The association was not explained by factors like race, family income, or other neighborhood characteristics, like the overall levels of poverty and unemployment.This suggests that something about exposure to violence, itself, may influence children's asthma risk, according to the researchers, led by Dr. Michelle J. Sternthal of the Harvard School of Public Health in Boston.The findings, published online in the European Respiratory Journal, are based on interviews with parents of 2,071 Chicago children, conducted three times over six years. More than 80 percent were African American or Hispanic. At the second interview, parents were asked about neighborhood violence -- specifically, how many times their child had ever seen someone physically assaulted or attacked with a weapon, or heard a gun shot. At the third interview, parents were asked whether their child had ever been diagnosed with asthma. Overall, Sternthal's team found, two-thirds of children in the study had been exposed to at least moderate levels of neighborhood violence, while 19 percent had been diagnosed with asthma. Asthmatic children were more likely than those without asthma to live in highly violent neighborhoods.Of children with asthma, 43 percent were from neighborhoods with a high level of violence, according to the researchers. That compared with 32 percent of kids without asthma. And while 36 percent of non-asthmatic kids lived in neighborhoods with little violence, that was true of only 22 percent of children with asthma. When the researchers considered a range of factors that might explain the connection, neighborhood violence itself remained linked to a higher asthma risk.It is plausible, according to Sternthal's team, that exposure to community violence could affect kids' asthma development. Chronic stress, for example, may affect the nervous and immune systems in a way that increases the risk of inflammatory diseases like asthma.Neighborhood violence may also affect asthma risk indirectly -- if, for example, it harms mothers' mental well-being and, along with that, their ability to care for their children. In addition, kids in violent neighborhoods may be unable to go outdoors and get exercise -- which could, the researchers say, promote obesity, a risk factor for asthma.It has long been known that asthma rates are higher-than-average in U.S. inner cities, with factors such as air pollution and indoor allergens believed to play a role. If neighborhood violence is in fact an asthma risk factor, Sternthal and her colleagues write, it could help explain the elevated rates of the disease in urban areas. It would also mean that experts need to look beyond traditional health-related measures to combat asthma in inner cities, the researchers point out. Efforts to reduce neighborhood violence, they say, could have additional benefits for children's health.European Respiratory Journal, online April 22, 2010.