COVID-19 in a Patient Previously Exposed to Toxic Disinfectant from a Humidifier

In August, 2011, the Korean Public Health Surveillance declared an outbreak of pulmonary disease due to the inhalation of humidifier disinfectants (HDs), which led to approximately 20,000 deaths. In March, 2020, the World Health Organization declared coronavirus disease-2019 (COVID-19) a pandemic. In this Case Report, we present a rare case of a patient who inhaled toxic HDs and developed COVID-19. He was young and had a low risk of severe COVID-19, however, he had a critical course to recovery. He was admitted to the intensive care unit and administered high-flow oxygen via a nasal cannula. He received dexamethasone injections each day for 10 days and his condition began to improve on hospital Day 6, although radiographical findings revealed no improvement. He was discharged on hospital Day 26. Despite the patient’s chronic lung disease becoming asymptomatic, HDs could be an important risk factor affecting the clinical course of COVID-19.