Approximately 90 percent of hazardous materials (hazmat) injuries are due to inhalation. In general, although some solids are highly hazardous (upon physical contact with the skin or if ingested into the body), gases and liquids with high vapor pressures pose the most significant risks to responders. These chemicals are more hazardous because they can become airborne, disperse, travel through the atmosphere, and be inhaled.
Vapor pressure (Vp), Boiling Point (BP), and Vapor density (Vd) are three (3) physical properties that are significant in determining risk.