This book is the sixth volume in the series Acute Exposure Guideline Levels for Selected Airborne Chemicals, and includes AEGLs for chemicals such as ammonia, nickel carbonyl and phosphine, among others. At the request of the Department of Defense, the National Research Council has reviewed the relevant scientific literature compiled by an expert panel and established Acute Exposure Guideline Levels (AEGLs) for 12 new chemicals. AEGLs represent exposure levels below which adverse health effects are not likely to occur and are useful in responding to emergencies such as accidental or intentional chemical releases in the community, the workplace, transportation, the military, and for the remediation of contaminated sites. Three AEGLs are approved for each chemical, representing exposure levels that result in: 1) notable but reversible discomfort; 2) long-lasting health effects; and 3) life-threatening health impacts.