Dispatchers who answer 911 calls can suffer emotional distress that can lead to symptoms of post-traumatic stress disorder, U.S. researchers say. Dr. Michelle Lilly of Northern Illinois University and researcher Heather Pierce, a former 911 dispatcher, analyzed the responses of 171 emergency dispatchers in 24 states. The majority of the sample was female and Caucasian, with an average age of 38 and more than 11 years of service, the researchers said. The dispatchers were asked about the types of potentially traumatic calls they handle and the amount of emotional distress they experienced. The study published in the Journal of Traumatic Stress found 16.4 percent of the dispatchers said worst calls were the unexpected injury or death of a child, 13 percent said suicidal callers, 10 percent said shootings involving officers and 10 percent said calls involving the unexpected death of an adult. The results showed that levels of distress dispatchers experienced during or after an event was high and occurred in reaction to an average of 32 percent of potentially traumatic calls. In addition, 3.5 percent of the sample reported symptoms severe enough to qualify for a diagnosis of PTSD. \"Post-traumatic psychological disorders are usually associated with front line emergency workers, such as police officers, firefighters or combat veterans,\" Lilly said in a statement. \"This is the first study on emergency dispatchers, who experience the trauma indirectly.\"