They study the effects of air conditioning at home and discover that (maybe) you should think twice before turning it on.

Air conditioning is a common resource for alleviating high temperatures, but its use without proper maintenance can lead to health problems . Recent research indicates that equipment in poor condition can facilitate the development of infections and the well-known sick building syndrome . Microbiologist Primrose Freestone has discussed this at length in an article for The Conversation .

Sick building syndrome is a cluster of symptoms that includes headaches, dizziness, nasal congestion, recurrent coughs, skin irritations, and fatigue . A 2023 study in India, involving a sample of 400 workers, found that those who spent six to eight hours a day in air-conditioned offices had more allergies , lower lung capacity, and a higher rate of work absences than those who worked in non-air-conditioned spaces.

Pollution and release of harmful substances

Experts indicate that the origin of these problems is often related to defective or poorly maintained equipment . In such cases, the equipment can emit chemical particles, allergens, and microorganisms into the air that should be filtered out. These substances include compounds such as benzene, formaldehyde, and toluene, all of which are harmful to the respiratory tract .

One of the most serious risks associated with poor air conditioning is the presence of the bacteria Legionella pneumophila , which causes the disease known as Legionella . This infection, similar to severe pneumonia, is contracted by inhaling small droplets of contaminated water . Its most common symptoms are fever, cough, malaise, and difficulty breathing. In many cases, it requires hospitalization.

Fungal proliferation and viral infections

The accumulation of moisture and dust inside air conditioning systems also favors the growth of fungi such as Aspergillus , Penicillium , and Cladosporium . In people with weak immune systems or pre-existing illnesses, these infections can become complicated and affect organs such as the liver, kidneys, or brain.

In some documented cases, air conditioning has been a vehicle for viral transmission. In a Chinese daycare center, a norovirus outbreak caused gastrointestinal symptoms in 20 children after the pathogen was released from a bathroom air conditioning unit. Although this virus is typically transmitted by contact , research confirmed that it was spread through the air.

The importance of cleaning and humidity control

Despite these risks, experts emphasize that a well-maintained air conditioner is not only safe, but can help reduce the presence of airborne pathogens , including respiratory viruses like SARS-CoV-2 . Regular filter cleaning and duct disinfection are essential to prevent problems.

Humidity control is also key. Spending long periods in excessively dry environments, which is common with the use of these devices, can dry out the nasal and throat mucous membranes , diminishing their defenses against bacteria and fungi. Therefore, combining thermal comfort with regular technical checkups is essential to protecting your health.