Nitrogen oxide
Nitrogen oxide (frequently abbreviated NOX) refers to one or more gaseous nitrogen-oxygen compounds that are toxic to many species, including Humans, when concentrated in sufficient quantities. 

In 2366, nanites that had infected the computer core of the  released nitrogen oxide onto the bridge of that starship in retaliation for Paul Stubbs' use of gamma radiation to destroy several of the nanites. ()

See also 
Nitrous oxide

External link 
 
Chemical compounds