Every day, there have been an average of 13 reports of vomit being found in Seoul's subway stations and trains since 2020, with alcohol consumption being the primary cause, data showed Thursday.

According to Seoul Metro on Thursday, 13,928 vomit-related complaints have been submitted to the company since 2020.

According to the survey, the complaints were the most frequent on Fridays, followed by Saturdays, accounting for 18.8 percent and 16.2 percent of the total, respectively.

When it comes to the time of day, the figure soars after 9 p.m. and reaches its peak at 10 p.m. Reports submitted after 9 p.m. account for 69.4 percent of the total.

Seoul Metro suspects that a large portion of the vomit accidents were caused by passengers heading home after “hoesik” -- official after-work company dinner and drinking gatherings -- or private drinking parties.

The yearly counts of these reports also gradually increased from 2020, early on during the pandemic when the operating hours of restaurants, cafes and multi-purpose facilities were restricted and when large gatherings were first banned, to the end of April 2022, when nearly all social distancing rules were lifted except for the mask mandate.

In 2022 alone, the number of reports was 5,059, higher than the figures in 2020 and 2021, 4,200 and 4,669, respectively, according to Seoul Metro.

Vomiting in public places causes hygiene issues. In one station in particular, there were more than 20 reports of vomit being found on one day, Seoul Metro said, leading to excessive labor for workers cleaning up the partially digested foods with paper towels.

It also causes safety risks as Seoul Metro shared the case of a 50-something passenger who slipped on vomit, fell and permanently injured their knee.

Seoul Metro requested in its announcement Thursday for passengers to report any vomit accidents as fast as they can to reduce such risks and inconveniences.