Fifty-nine guests and employees at the Grand Chosun Jeju required medical treatment on October 1 after chlorine gas escaped from a first-floor pool during routine disinfection and spread through the hotel's sauna, swimming pool, and upper guest floors.

The five-star property sits in the Jungmun Tourist Complex in Seogwipo, a resort district on Jeju Island's southern coast that anchors much of the destination's luxury hotel supply. The operator, Chosun Hotel & Resort, runs the Grand Chosun brand domestically.

What triggered the leak?

Jeju Fire and Safety Headquarters determined the gas released when staff applied disinfectant to the pool in the morning. The fumes traveled through the building's ventilation, reaching the sauna area and the rooms above. Symptoms reported by those exposed included nausea, vomiting, coughing, tearing, and runny nose.

Paramedics from the 119 emergency service distributed dozens of affected guests to nearby hospitals, including Seogwipo Medical Center. Among those treated were infants who had been in the sauna at the time of exposure.

How did the hotel respond?

Guests disputed the property's handling. Several told local media that staff never issued a clear evacuation order. Workers wore masks, the guests said, but did not distribute masks to visitors.

A hotel official acknowledged gaps in the response: "At the time of the accident, we visited the room with the broadcast and guided the evacuation, but it seems that the customer in the bathroom or sauna did not hear the broadcast." The same official added: "We tried to provide masks on time, but there may be some customers who missed them because the site was very confused."

What is the regulatory exposure?

Police and fire authorities are now examining swimming-pool facility personnel for compliance with disinfectant-handling rules. The investigation covers both the leak's cause and the hotel's emergency-response execution.

For hotel operators, the case touches three risk lines that drive liability and insurance pricing: chemical-handling SOPs for aquatic facilities, HVAC design that isolates mechanical and pool-air systems, and crisis-communication playbooks that go beyond broadcast announcements to direct, room-by-room contact.

What is the operator's exposure?

Chosun Hotel & Resort has not disclosed whether the pool and sauna will reopen before the probe concludes. The company said it "plans to come up with a way to minimize the inconvenience of guests" affected by the incident. That language is standard post-incident phrasing, but the regulatory findings will determine whether the property faces fines, license suspension, or civil claims from the 59 people who required care.

Jeju's luxury hotel market depends heavily on Korean domestic tourism and a high-spending family segment, both of which are sensitive to safety reporting. The Jungmun complex in particular competes on amenity-rich family offerings, and the pool-spa stack is the core of that positioning.

The police and fire findings, expected in the coming weeks, will set the template for how Korean resort operators document and supervise the use of chlorine-based pool chemicals at high-occupancy properties.