The Swedish armed forces have during the last ten years been using green small calibre ammunition 5,56 mm sk ptr 5B stkprj. The Swedish armed forces has commissioned FOI to investigate what measures can be taken to reduce the health risks associated with firing green ammunition. In order to investigate the substances that are emitted when shooting with small calibre ammunition, an experimental test was performed with four different types of ammunitions and three weapon models. In field experiments the levels of particles and gases on a shooting range were measured during a standard exercise and during a high volume fire test for a single shooter. Within the project a questionnaire survey was conducted directed to the training units and schools of the armed forces, with the aim of clarifying the extent of the problems of adverse health effects within the Swedish armed forces today. The survey showed that about one fourth had experienced discomfort such as irritated eyes, nose and throat and coughing. A small number had experienced more lasting and serious symptoms as well. The experimental tests showed higher levels of copper, zinc, ammonia and hydrogen cyanide in the lead-free ammunition than in its predecessor 5,56 mm sk ptr 5 stkprj (containing lead). The levels of carbon monoxide were high for all types of ammunition tested. Measurements from the range showed low levels of gases and particles during a normal exercise but slightly elevated levels of copper for both the lead containing and lead free ammunition during the high volume fire tests. Carbon monoxide was found at levels above the exposure limit during the short intervals of shooting. The other measured substances were found at low levels. Recommended measures to reduce adverse health effects are primarily to reduce the exposure to gases and particles by ensuring adequate ventilation at shooting ranges, use of protective masks where applicable (e.g. during high volume fire in materiel testing) and adapt firing exercises to available renge conditions. Procedures for reporting and follow up of symptoms should also be established at the training units. In future procurement of ammunition, health aspects should be regarded and the levels of emitted combustion gases and particles should be measured in order to facilitate evaluation of possible adverse health effects.