Air conditioning can be a real blessing during hot summer days. It maintains a pleasant temperature and controls humidity, making the interior environments beganable even during heat waves. However, some people avoid using air conditioning, whatever the outside temperature, lest it make them sick. You could find it exaggerated, but as a microbiologist, I can say that this fear is not completely unfounded.
Indeed, if an air conditioning system works poorly or is not properly maintained, it can be contaminated by infectious microbes. Your air conditioner can then become a potential source of many infections transmitted by air, ranging from simple cold to pneumonia.
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Unhealthy buildings syndrome
The “unhealthy buildings syndrome” is the generic name given to the symptoms that may appear after a prolonged stay in air -conditioned environments. These symptoms may include headache, dizziness, congestion or nasal flow, persistent cough or whistling breathing, itching and rashes, concentration and fatigue disorders.
This syndrome generally affects people who work in offices, confined spaces, but it can occur in anyone spending long periods in air -conditioned buildings, such as hospitals or other public buildings. Symptoms of unhealthy buildings syndrome tend to worsen over time in a given building, and diminish after departure.
An Indian study carried out in 2023 compared 200 healthy adults working at least six to eight hours a day in an air -conditioned office at 200 healthy adults not working in an air -conditioned environment. The group exposed to air conditioning has presented more symptoms associated with unhealthy building syndrome during the two -year study period, in particular a higher prevalence of allergies. It is important to note that clinical tests have shown that people exposed to air conditioning have a lower pulmonary function and were more often on sick leave than those who were not exposed to it.
Air pollution
Other studies have confirmed that office employees working in air -conditioned premises had a higher prevalence of unhealthy building syndrome than those who did not work in an air -conditioned environment. It is suspected that one of the causes of unhealthy buildings syndrome is the malfunction of air conditioners. When an air conditioner does not work properly, it can release allergens, chemicals and suspended microorganisms in the air which should normally have to be trapped by filters.
Defective air conditioners can also release chemical vapors from cleaning products or refrigerants in the air of the building. Chemicals such as benzene, formaldehyde and toluene are toxic and can irritate the respiratory system.
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Legion bacteria
Poorly maintained air conditioning systems can also house pathogenic bacteria likely to cause serious infections.
Legionella Pneumophila is the bacteria responsible for the “legionnaire disease”, a pulmonary infection. Contamination is made by respiratory route, by inhalation of contaminated water broadcast in aerosol. It generally develops in water -rich environments, such as jacuzzis or air conditioning systems.
Air conditioners must be properly disinfected and maintained to avoid the spread of infections. Photo: Peerakorn chotthanawarapong / istock
The legionellosis most often contracts in collective places such as hotels, hospitals or offices, where the bacteria contaminated water. The symptoms of legionnaire disease are similar to those of pneumonia: coughs, shortness of breath, chest disturbance, fever and general influenza symptoms. Symptoms generally appear between two and fourteen days after contamination by legionella. Legionella infections can be fatal and often require hospitalization. Healing can take several weeks.
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Fungal and viral infections
The accumulation of dust and humidity inside air conditioning systems can also create conditions conducive to the proliferation of other infectious microbes. For example, research on hospitals air conditioning has shown that fungi such as Aspergillus, Penicillium, Cladosporium and Rhizopus species frequently accumulate in the water rich in hospital ventilation systems.
These fungal infections can be serious in vulnerable patients, such as those who are immunocompromised, who have undergone an organ transplant or who are under dialysis, as well as in premature babies. Aspergillus, for example, causes pneumonia, pulmonary, cerebral, hepatic, splenic and renal abscesses, and can also infect burns and wounds. The symptoms of fungal infections are mainly respiratory and include whistling breathing or persistent cough, fever, shortness of breath, fatigue and unexplained weight loss.
Viral infections can also be contracted by air conditioning. A case study revealed that children from a Chinese kindergarten class had been infected with the Norovirus from their air conditioning system. This caused gastroenteritis for 20 students. While norovirus is generally transmitted by close contact with an infected person or after having touched a contaminated surface, in this specific case, it was confirmed that, unusually, the virus had spread in the air, from the class air conditioning system. Several other cases of this type have been reported.
However, air conditioners can also help prevent the spread of viruses suspended in the air. Research shows that regularly maintained and disinfected air conditioners can reduce the levels of circulation of current viruses, including COVVI-19. The risk of air conditioning infection also comes from the fact that it lowers the air humidity. The indoor air is drier than the outside air.
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Dry mucous membranes
Passing long periods in low -moisture environments can dry up the mucous membranes of your nose and throat. This can affect their ability to prevent bacteria and fungi from entering your body and making you more vulnerable to the development of a deep tissue infection.
The air conditioners are designed to filter atmospheric contaminants, fungal spores, bacteria and viruses to prevent them from entering the air that we breathe inside. But this protective shield can be compromised if the system filter is old or dirty, or if the system is not cleaned. Thus, it is essential to ensure good maintenance of air conditioning to prevent infections related to air conditioning.
The original version of this article was published in The Conversation.
