There were many health problems caused by the toxins. 99% of exposed firefighters reported at least one new respiratory problem while working at the World Trade Center site that they had not experienced before. Chronic airway disease is the main lung injury among firefighters who were exposed to toxins during 9/11. Six years after the attacks, among those who never smoked, approximately 13% of firefighters and 22% of EMS had lungs that did not function as well as others around the same age. Steep declines in pulmonary lung function has been a problem since first detected among firefighters and EMS within a year of 9/11 have persisted.