The University of Iowa

SAFETYmatters - Isoflurane Anesthetic Gas Use

Article published 01/29/18

With the increasing use of isoflurane in animal research and the potential health hazards associated with high concentration levels, EHS encourages users to keep exposures to the anesthetic gas as low as reasonably achievable.  To reduce the risk to users, it is important to prevent waste anesthetic gas (WAG) from escaping into the workspace. 

Based on evaluations done at numerous institutions, there are two primary activities where the potential risk of exposures have been found:

  1. Not ensuring a tight seal around the animal nose cone, and
  2. Failing to flush the induction chamber with oxygen prior to opening the chamber to transfer animals (Note: the induction chamber must be attached to a WAG scavenging system.)

When using a nose cone to deliver the anesthetic gas, make sure to achieve a tight seal around the animal’s nose (for rodents and rabbits) and around the animal’s nose and mouth for all other animals.   

  • When purging the induction chamber via the oxygen flush button, use an appropriate scavenging system to ensure no WAG escapes into the workspace.
  • To evaluate staff exposure risks, please contact P. Subramanian (Subbu) at EHS (  

Further guidance will be forthcoming.