*3.4. Health Risk Assessment of VOCs*

Benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene are the important VOCs species in the atmosphere of Jinghong, and the proportion of aromatic hydrocarbons was ~58.70%. Table 6 compares the noncarcinogenic and carcinogenic risks of BTEX (benzene, toluene, ethylbenzene, m/p-xylene, o-xylene) mass concentration in Jinghong with other cities. The results show that the noncarcinogenic risk values of benzene > m/p-xylene > o-xylene > ethylbenzene > toluene in both the dry and rainy season of suburban sampling

sites, and benzene > m/p-xylene > o-xylene > toluene > ethylbenzene in both the dry and rainy season of urban sampling sites, ranging from 1.01 × 10−<sup>4</sup> to 7.75 × 10<sup>−</sup>2, were within the safe range (HQ < 1) as determined by the US EPA. The lifetime carcinogenic risk value of benzene ranged from 9.02 × 10−<sup>6</sup> to 1.82 × 10<sup>−</sup>5, which is higher than the safety range (R < 1.00 × 10<sup>−</sup>6) as determined by the US EPA. These results indicate the existence of carcinogenic risk and the possibility of inducing lymphatic system immune diseases and leukemia in humans exposed to the environment for an extended time, which should be taken more seriously.

**Figure 4.** Trajectory clustering from July 2016 to June 2017.

**Table 5.** Statistical results of various trajectory pollutant concentrations from July 2016 to June 2017 in Jinghong.


The changing trend of the noncarcinogenic risk quotient in Jinghong shows that benzene and toluene had higher noncarcinogenic risk quotient values, which was the same as those of Guangzhou [32] and Beijing [46]. However, it was shown that benzene and xylene had higher noncarcinogenic risk quotients in Chengdu [34] and Xiamen [47], while xylene had higher quotients in Lanzhou [48], and benzene had a higher quotient in Port Moody (Canada), Burnaby South (Canada) [49], and Tabriz (Iran) [50]. In this study, HI values were higher in urban areas than in suburban areas, and lower in Jinghong than in other cities. The lifetime carcinogenic risk of benzene was low compared to other cities, except for the dry season suburban area and rainy season urban area, which were higher than that of the residential sampling site in Xiamen (1.23 × 10<sup>−</sup>5). Overall, it was shown that the health risk level in Jinghong was lower than its urban counterparts, However, it should be noted that the carcinogenic risk value of benzene in this region has exceeded the safety threshold. Therefore, it is necessary to increase the control of benzene emissions to reduce its carcinogenic risk.



"-" means that there are no such data in the references.
