Virus transmission risk of college students in railway station during Post-COVID-19 era: Combining the social force model and the virus transmission model.

In the post-epidemic era, people's lives are gradually returning to normal, and travel is gradually resuming. The safe evacuation of cross-regional travelers in railway station has also attracted more and more attention, especially the evacuation behavior of college students in railway station. In this paper, considering the pedestrian dynamics mechanism in the emergency evacuation process during the COVID-19 normalized epidemic prevention and control, an Agent-based social force model was established to simulate the activities of college students in railway station. Combined with the virus infection transmission model, Monte Carlo simulation was used to calculate the total exposure time and the number of high-risk exposed people in the railway station evacuation process. In addition, sensitivity analysis was conducted on the total exposure time and the number of high-risk exposed people under 180 combinations of the number of initial infections, social distance, and the proportion of people wearing masks incorrectly. The results show that with the increase of social distances, the total exposure time and the number of high-risk exposures do not always decrease, but increase in some cases. The presence or absence of obstacles in the evacuation scene has no significant difference in the effects on total exposure time and the number of high-risk exposures. During the evacuation behavior of college students in railway station, choosing the appropriate number of lines can effectively reduce the total exposure time and the number of high-risk exposures. Finally, some policy suggestions are proposed to reduce the risk of virus transmission in the railway station evacuation process, such as choosing dynamic and reasonable social distance and the number of queues, and reducing obstacles.

Concentrations and Related Health Risk Assessment of Pesticides, Phthalates, and Heavy Metals in Strawberries from Shanghai, China.

ABSTRACT: In the present study, a risk assessment of pesticides, phthalates, and heavy metals in strawberries (n = 335) in recent years was conducted by determining the estimated daily intake, target hazard quotient, and hazard index. The study used 128 pesticides, 18 phthalates, and three heavy metals in this determination. It detected 51 pesticide residues in the strawberry samples, and 97.91% samples had levels of at least 1 of the 51 pesticides above the limit of detection. In addition, 2.39% of samples had pesticides higher than the Chinese maximum residue limit. Multiple pesticide residues were detected in most samples. Bis-2-ethylhexyl phthalate, diisobutyl phthalate, and dibutyl phthalate were detected in the strawberry samples, with a high frequency of detection. Their detectable rates were 100, 100, and 89.9%, respectively. In most samples, lead, cadmium, and nickel were detected, with detectable rates 75.76, 92.93, and 92.93%, respectively. The estimated daily intake of analyzed pesticide, phthalate, and heavy metal residues appears to be relatively low compared with the acceptable daily intake. The average target hazard quotients and hazard indices were less than 1. That means that customers who are exposed to the average contaminant levels may not pose a significant health risk. Our results show that the strawberries may be polluted by many kinds of contaminants. Therefore, monitoring of pesticide, phthalate, and heavy metal residues in strawberries should be increasingly developed to fully protect the health of the consumer.