fig2

Figure 2. Concentration distribution of widely detected TDCs in road dust (n = 24 for each compound). The box represents the IQR from the 25th to the 75th percentile; the black line inside the box denotes the median; the open square (□) indicates the mean; and diamond symbols (◆) represent outliers (extending to the minimum and maximum values within 1.5× IQR). TDCs: Tire-derived chemicals; IQR: interquartile range; DPG: 1,2-diphenylguanidine; 6PPD: 4-N-(4-methylpentan-2-yl)-1-N-phenylbenzene-1,4-diamine; 2-OH-BTH: 3H-1,3-benzothiazol-2-one; RD: 2,2,4-trimethyl-1H-quinoline; BTH: 1,3-benzothiazole; 6PPD-Q: 2,5-dianilinocyclohexa-2,5-diene-1,4-dione; DTPD: 2-(cyclohexylamino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione; 4-HDPA: 4-anilinophenol; HMMM: hexa(methoxymethyl)melamine; 2-Me-S-BTH: 2-methylsulfanyl-1,3-benzothiazole; 2-ABTH: 1,3-benzothiazol-2-amine; DPU: 1,3-diphenylurea; BT: 2H-benzotriazole; DPPD: 1-N-cyclohexyl-4-N-phenylbenzene-1,4-diamine; IPPD: 1-N,4-N-diphenylbenzene-1,4-diamine; IPPD-Q: 2-anilino-5-(propan-2-ylamino)cyclohexa-2,5-diene-1,4-dione; DTPD-Q: 1-N-phenyl-4-N-propan-2-ylbenzene-1,4-diamine; DCA: N-cyclohexyl-N-methylcyclohexanamine; TBBS: N-(1,3-benzothiazol-2-ylsulfanyl)-2-methylpropan-2-amine; DNPD: 1-N,4-N-dinaphthalen-2-ylbenzene-1,4-diamine; CPPD: 2-anilino-5-(4-methylpentan-2-ylamino)cyclohexa-2,5-diene-1,4-dione.