Exposure to stressful events during a peacekeeping mission may have a price: The impact on trait of negative and positive affect and mental health.

We evaluated the participants' negative affect, positive affect, post-traumatic stress disorder, and depression symptoms before and after a peacekeeping mission. Depression symptoms and positive affect after mission were significantly associated with exposure to stressful events during the mission, controlled by the respective characteristics before mission. Negative affect and post-traumatic stress disorder symptoms after mission had a tendency to be associated with exposure to stressful events during the mission, controlled by the respective characteristics before mission.