This　study　conducted　long-term　monitoring　of　the　emission　fluxes　and　ambient　air　concentrations　of　volatile　aldehydes　and　ketones　released　from　each　treatment　unit　of　an　A　/　O　process　urban　wastewater　treatment　plant　in　Beijing,　evaluated　the　emission　characteristics　of　four　typical　aldehydes　and　ketones　on　the　spatial　scale,　and　calculated　the　exposure　risk　values　of　each　process　unit　to　assess　the　hazards　of　aldehydes　and　ketones　to　the　staff　and　the　neighbourhood　residents.　Results　show　that　the　emission　fluxes　of　volatile　aldehydes　and　ketones　compounds　in　the　wastewater　treatment　plant　are,　in　descending　order:　aerobic　tank　section　1　＞　aerobic　tank　section　2　＞　aerobic　tank　section　3　＞　anoxic　tank　＞　primary　sedimentation　tank　＞　secondary　sedimentation　tank.　The　BAF　is　the　treatment　unit　with　the　largest　percentage　of　daily　emissions　of　aldehydes　and　ketones　among　the　treatment　units,　with　more　than　57.　81%　of　the　four　aldehydes　and　ketones　gases.　The　ambient　concentrations　of　aldehydes　and　ketones　in　the　ambient　air　of　each　treatment　unit　also　varies,　with　the　total　concentration　varying　from　30.　44　to　1　230.　79　μg/　m3,　of　which　formaldehyde　has　the　lowest　concentration　content,　ranging　from　2.　46　to　71.　36　μg/　m3,　and　acetaldehyde　has　the　highest　concentration,　ranging　from　59.　32　to　1　454.　44　μg/　m3.　There　is　a　carcinogenic　risk　of　acetaldehyde　emitted　from　each　treatment　unit.　©　2023　Beijing　University　of　Technology.　All　rights　reserved.