NOx: A general chemical formula to represent a number of nitrogen oxides. e.g., NO and NO2. These tend to form in exhaust gases of an engine when combustion temperatures are high or the air-fuel mixture is lean. Related posts: Personnel Management Operative Functions Administrative Role of PM Competency HR Management Role Change Personnel Policies Personnel Procedures Appealed Policies Implied Policies Specific Policies Personnel records Research Pure research Personnel research Attitude or Opinion Survey Turnover Secondary research Applied research Personnel audit Read more articles Previous PostNaturally aspirated engine Next PostOctane number