Monoterpene　is　a　biogenic　volatile　organic　compound　commonly　found　in　cleaning　products　and　air　fresheners.　It　can　react　rapidly　with　indoor　oxidants,　such　as　ozone　(O3),　to　produce　secondary　organic　aerosols　(SOAs)　in　indoor　environments,　and　the　reactions　are　potentially　influenced　by　ammonia　(NH3).　This　study　simulated　the　reactions　of　O3　and　monoterpene　with　and　without　the　presence　of　NH3　in　an　environmental　chamber　and　investigated　the　surface　characterization　(elemental　components　and　carbon　states)　of　the　PM2.5　generated　by　these　reactions.　We　found　that　the　generated　particles　possessed　a　higher　content　of　nitrogen-containing　organic　compounds　when　NH3　was　present.　Unsubstituted　aromatic　carbon　and　aliphatic　carbon　were　the　main　carbon　structures,　exhibited　by　over　60%　of　the　carbon-containing　compounds.　Additionally,　in　the　presence　of　NH3,　more　amide　carbon　and　carboxylic　carbon　formed　during　the　reactions.　We　also　examined　acute　lung　injury　in　mice　caused　by　new　particle　formation　under　different　reaction　conditions.　Oxidative　stress　was　observed　in　the　bronchoalveolar　lavage　fluid　of　the　mice,　as　evidenced　by　a　decrease　in　antioxidant　enzymes　(superoxide　dismutase)　and　antioxidants　(glutathione)　as　well　as　an　increase　in　malondialdehyde.　Moreover,　the　SOAs　generated　in　the　presence　of　NH3　lowered　glutathione　levels,　indicating　a　rise　in　oxidative　stress.　Hence,　fine　particles　formed　by　indoor　oxidative　reactions　may　trigger　acute　lung　injury　in　humans,　potentially　causing　further　respiratory　disease.　©　The　Author＇s　institution.