In　this　study,　the　traffic　characteristics,　environmental　parameters,　and　concentration　of　vehicle　exhaust　pollutants　of　the　Yingtian　avenue　in　the　Yangtze　river-crossing　tunnel　in　Nanjing,　China,　are　examined　to　thoroughly　investigate　the　emission　and　distribution　characteristics　of　vehicle　exhaust　pollutants.　The　traffic　characteristics　are　statistically　analyzed　using　video-recording　methods,　revealing　a　distinct　diurnal　variation　pattern,　with　drastically　higher　traffic　flow　in　the　morning　peak　than　the　evening　peak,　and　an　inverse　relationship　between　vehicle　speed　and　traffic　flow.　Night-time　testing　indicates　that　pollutant　concentrations　inside　the　tunnel　initially　increase　and　then　decrease　along　the　length　of　the　tunnel,　with　the　PM2.5　concentration　peaking　at　the　bottom　of　the　V-shaped　terrain　of　the　tunnel.　The　CO　concentration　peak　appears　slightly　later　than　the　PM2.5　peak　because　of　the　influence　of　the　activated　fans　at　the　tunnel　exit.　During　daytime　testing,　when　the　fans　are　off,　the　pollutant　concentration　peaks　at　the　tunnel　exit.　In　the　morning　peak,　the　maximum　concentrations　of　CO　and　PM2.5　at　the　tunnel　exit　are　31.0　mg/m3　and　145　μg/m3,　respectively,　which　are　3.1　and　2　times　the　concentration　limits,　respectively.　The　Pearson　correlation　analysis　conducted　to　examine　the　relationships　between　various　parameters　reveals　a　strong　positive　correlation　between　the　CO　concentration　and　the　number　of　gasoline　vehicles　and　a　strong　positive　correlation　between　the　PM2.5　concentration　and　the　number　of　diesel　vehicles.　Both　pollutants　are　strongly　negatively　correlated　with　wind　speed　in　the　tunnel.　©　2024　Editorial　Office　of　Tunnel　Construction.　All　rights　reserved.