In 2011, many pregnant women in South Korea died of unexplained lung disease. Since then, similar cases have continued to increase, causing panic in Korean society. After 10 years of investigation, finally on July 27th, local time this year, the South Korean Special Commission for Social Disaster Investigation held a press conference to announce the latest findings on the incident.

The survey results show that from 1994 to 2011, a total of about 6.27 million people in South Korea have used humidifier fungicides, and it is estimated that about 670,000 of them have suffered health damage. Approximately 550,000 out of the 670,000 people received relevant treatment, and a total of approximately 14,000 people died from related diseases caused by humidifier fungicides. This number far exceeds the number of victims of humidifier fungicides currently controlled by the Korean government.

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The investigation found that the humidifier disinfectant produced by the South Korean branch of the British Reckless Group contained polyhexamethyleneguanidine hydrochloride (PHMG), which was the prime culprit for death. Many victims in the incident used humidifiers for about 4 months a year on average, adding a fungicide every time they added water, and used up one bottle of fungicide in about a month.

The victim’s family member Lee said in an interview with South Korean media that his wife would buy a humidifier disinfectant every winter before his death. Even after suffering from interstitial pneumonia, a humidifier will be turned on in the ward. "The humidifier disinfectant that was originally bought for the health of the family has now taken the lives of the family."

According to an official from the Ministry of Environment of South Korea, PHMG was initially reviewed for its use as a carpet fungicide and regarded as a common chemical substance; when the use changes, for example, as a humidifier fungicide, its harmfulness should be reviewed again. "There is no such system yet."

PHMG is usually used as a derivative biocide disinfectant, which has the properties of detergent, anticorrosion agent and flocculant, and prevents biofouling. Since 2001, PHMG has been widely used in Korea as a disinfectant to prevent microbial contamination in household humidifiers.

"PHMG is very harmful to the human body through atomization and inhalation. While killing bacteria, it also causes damage to the alveoli of human airway epithelial cells, which can cause acute and chemical inflammation. In severe cases, it can even cause acute intermittent inflammation. The professional name of qualitative pneumonia is Humidifier Disinfectant-related Lung Injury." Tan Jianlong, a respiratory physician at Hunan Provincial People’s Hospital, told the Health Times reporter that most of the patients in the Korean incident died of acute interstitial pneumonia.


Why is the fatality rate of the humidifier fungicide incident in Korea so high? Dr. Tan Jianlong said that there are probably two reasons. On the one hand, due to the respiratory toxicity of the substance, bronchiolitis obliterans and alveolar damage caused by inhalation of this substance are irreversible, eventually leading to pulmonary fibrosis, which seriously affects respiratory function. On the other hand, it is related to the season and the crowd. In winter, people use humidifiers frequently and inhale more frequently. Due to special physiological changes, it is difficult for pregnant women to recover once a problem occurs; children are more susceptible to such external stimuli and damage due to immature lung development. Therefore, we have seen that children and pregnant women are more common among Korean patients.

A reporter from the Health Times found that when searching for humidifier disinfectants on individual e-commerce platforms, some related products can be retrieved.

Tan Jianlong pointed out that adding a fungicide to a humidifier can have a sterilization effect. First of all, it is uncertain; secondly, inhaling these substances will cause damage to our respiratory system, including asthma, chronic bronchitis, and lung gas. Patients with chronic respiratory diseases such as swelling patients, after inhaling these substances, may also induce an acute attack of the disease.

"The living environment of our ordinary people does not need to be air disinfected. Natural ventilation is enough in the home. It is enough to open the windows to allow air convection. During the epidemic, doctors also recommended that everyone do it." Tan Jianlong said.


Some people also like to add aromatherapy, vinegar, lemon juice, etc. to the humidifier. This practice is also not recommended. Tan Jianlong pointed out that the composition of these substances may be more complex than some chemical substances, the damage to the human respiratory system is more difficult to identify, the pungent smell produced is stronger, and it is easier to induce the onset or aggravation of acute respiratory diseases in sensitive people. In addition, the mist aerosol produced by the humidifier can reach deeper and even deposit in the alveoli, causing more direct and serious damage.

Tan Jianlong suggested that the humidifier in the home should be cleaned regularly and then allowed to dry for a period of time. It is best not to use it continuously for a long time. In addition, it is not recommended to add tap water to the humidifier. Tap water is easy to breed microorganisms, which may cause harm to the human body after inhalation, and potential risk of disease. It is best to use purified or distilled water, or use cold water that is boiled and cooled.