Compressed gases and cryogenic liquids are similar in that they can create pressure hazards and can also create health hazardous and/or flammable atmospheres. One special property of compressed gases and cryogenic liquids is that they undergo substantial volume expansion when released to air, potentially depleting workplace oxygen content to hazardous levels.

 Toxic gases pose additional potential acute health hazards to laboratory personnel and the public, and as such, are considered Stanford University “Restricted Chemicals” that require prior approval by the PI/Laboratory Supervisor. The Santa Clara County Toxic Gas Ordinance regulates the use, handling, distribution and dispensing of toxic gases. In addition, it contains specific provisions mandating facility permitting, engineering controls, protective equipment, storage requirements, emergency response plans, warning systems and employee training based on the type and quantity of toxic gas used. As usage of toxic gases may require special permits, contact EH&S for further guidance. For specific requirements on toxic gases, refer to the Toxic Gas subtopic.