A 32-year-old man in China narrowly escaped death after developing a severe lung infection believed to have been caused by turning on an air conditioner that had been left unused for six months without proper cleaning.
According to reports from Chinese media, the man from Wuhan began using the air conditioner as temperatures started rising earlier last year.
After using the unit continuously for three days, he developed symptoms including high fever, muscle aches and a dry cough. Initially believing it was just a common flu, he attempted self-medication at home.
However, his condition rapidly worsened and later progressed to chest tightness and breathing difficulties.
The man eventually sought treatment at Wuhan Third Hospital, where a chest CT scan revealed a serious infection covering a large portion of his left lung.
Doctors later diagnosed him with Legionnaires’ disease, a severe form of pneumonia caused by Legionella bacteria, commonly linked to contaminated water systems and poorly maintained air-conditioning units.
The patient reportedly required intensive emergency treatment before eventually recovering from the life-threatening infection.
Respiratory specialist Bao Min warned that many people mistakenly believe cleaning the air-conditioner filter alone is sufficient.
She explained that internal components such as evaporators, fans and water trays are often breeding grounds for dangerous bacteria, mould and fungi, especially after long periods of inactivity during cooler seasons.
“When an uncleaned air conditioner is switched on, invisible bacteria can spread through the cool air into enclosed indoor spaces and enter the lungs through breathing,” she said.
Health experts warned that elderly individuals, children, pregnant women and those with weakened immune systems face higher risks of severe infection.
According to the Centre for Health Protection, Legionnaires’ disease is mainly spread through inhalation of contaminated water droplets or mist, with symptoms usually appearing between two and 10 days after exposure.
Experts advised the public to thoroughly clean air-conditioning units before first use during hot weather.
Recommended steps include washing filters with mild detergent, disinfecting internal cooling components, running the unit in heating mode to remove moisture and ventilating rooms properly before regular use.
Specialists also suggested opening windows for ventilation every two to three hours during prolonged air-conditioner use and setting temperatures at around 26°C to reduce respiratory irritation and improve indoor air quality.
