The gas, phosphine, forms when pesticides containing aluminum phosphide mix with water. These pesticides are restricted to certified users because short-term exposure can cause respiratory and cardiovascular, or heart and blood vessel, complications, and can be fatal. Federal regulations require emergency crews on the scene with such hazardous substances wear personal protective equipment, including a respirator. Multiple studies, however, show this does not typically happen. Little information is currently available on how to increase emergency responders’ compliance.