As　secondary　aerosols　become　larger　fractions　of　ambient　PM2.5,　emission　factors　and　source　profiles　need　to　reflect　the　photochemical　aging　of　multipollutant　emissions　that　account　for　changes　in　transport　between　source　and　receptor.　Oxidation　Flow　Reactors　(OFR)　intend　to　simulate　gas/particle　transformation　and　volatilization　with　time-scales　of　hours　to　days　in　order　to　estimate　mass　gains　or　losses　due　to　atmospheric　aging.　The　commercially-available　Potential　Aerosol　Mass　(PAM)-OFR　(Aerodyne　Research,　LLC,　Billerica,　MA,　USA)　is　evaluated　for　its　feasibility　in　establishing　an　emission　limit　certification　protocol　for　China　and　for　determining　changes　to　source　marker　abundances　used　in　source　apportionment　model　applications.　The　OFR　without　ultraviolet　radiation　is　reasonably　inert　to　the　passage　of　reactive　gases,　such　as　sulfur　dioxide　(SO2),　and　particles　＞~100　nm.　The　largest　uncertainty　in　estimating　aging　times　is　the　commonly　used　assumption　that　the　average　atmospheric　hydroxyl　concentration　(OHatm)　is　1.5　×　106　molecules/cm3;　measurements　show　that　OHatm　can　vary　by　an　order　of　magnitude　in　different　environments.　OH　exposures　(OHexp)　estimated　within　the　OFR　are　more　precise　than　this　assumption.　Plug　flow　is　a　reasonable　estimate　of　residence　time　within　the　OFR,　as　it　does　not　differ　much　from　the　weighted-mean　of　the　residence　time　distribution.　A　survey　of　previous　studies　shows　that　only　a　few　examine　the　PAM-OFR　performance,　and　that　mass　is　both　gained　and　lost　with　aging,　depending　on　the　combustion　fuels,　burning　conditions,　and　aging　times.　At　present,　the　OFR　appears　to　be　more　practical　for　source　profile　aging　than　for　emission　certification,　and　further　experiments　are　needed　prior　to　application　for　multipollutant　effects　on　particulate　emission　rates.　©　2019　Elsevier　Ltd