Well used, air conditioning clearly improves comfort during strong heat. But under certain conditions, it can also become a source of discomfort or respiratory problems, especially in fragile people.
Rhumes, headaches, conjunctivitis and other allergic symptoms: what if it was air conditioning?
One of the first side effects is the drought of the air. By lowering the ambient humidity, air conditioning dries up the mucous membranes of the nose, the throat or the eyes, which promotes irritation, dry cough or sensation of embarrassment making the bed of angina and other colds.
Another frequent pitfall: the temperature differences that are too marked between the outside and the air -conditioned spaces. These thermal shocks can cause headache, chills or muscle tensions, especially in the neck and back.
In extreme cases, very large temperature differences can cause brutal vasoconstriction. This vascular system reaction can, in some people, lead to discomfort or even loss of knowledge. Cardiac arrest is however extremely rare in this context.
The need for regular maintenance
The air quality diffused also depends on the system of the system. “If the filters are not cleaned regularly,” warns Dr. Le Guillou, “ They can accumulate dust, mold or bacteria, then dispersed in indoor air. In rare cases, some infections such as legionellosis have been associated with poorly maintained air conditioning systems. »»
Legionellosis is a pulmonary infection caused by a bacteria called Legionella pneumophila which can develop in poorly maintained air conditioning systems, especially in cooling towers (those using water, as in hospitals, etc.). When dispersed in the air in the form of fine droplets, it can be inhaled, causing often severe pneumonia.
In general, insufficient ventilation, in enclosed places, can also promote the circulation of viruses.
In addition, some devices can concentrate allergens or put them in suspension, stirring the air in insufficiently ventilated rooms. Dust, mites, mold spores, animal hair: these interior pollutants can then trigger or worsen allergic reactions.
Air conditioning sensitivity, a medical reality?
Some people are actually more sensitive to the effects of air conditioning.
“This is the case with those whose mucous membranes are fragile, especially in case of allergies, asthma or sinusitis,” recalls the pulmonologist. Dry air or suspension allergens can accentuate their symptoms. A weakened immune system also makes more vulnerable to infectious agents that a poorly maintained device can convey. People with chronic respiratory diseases, such as chronic obstructive bronchopneumopathy (COPD), or those sensitive to temperature variations, are also more exposed to side effects. »»
Finally, children and the elderly, due to their less effective thermal regulation or the fragility of their mucous membranes, are particularly reactive to an overly cold atmosphere. Prolonged exposure to an air conditionedly adjusted air, a fortiori without sufficient hydration, can worsen these reactions.
Well adjust the temperature of its air conditioning
To limit the adverse air conditioning effects, some simple measures can be put in place:
– the interior temperature must remain moderate, with an ideal difference of 5 to 7 ° C compared to the outside, never more than 10 ° C;
– The cold air flow must be oriented towards the ceiling rather than directly on people;
– Use filters with good health performance (e.g. HEPA) as the Ministry of Health mentions;
– and regular maintenance of the system is essential: filters must be changed and cleaned frequently to avoid the accumulation of dust or microorganisms.
– The UFC Que Choisir advises to dust off the air mouths with soapy water. Although no inspection or maintenance contract obligation exists for consumer air conditioners (only the powers greater than 12 kW or the devices containing more than 4 kg of refrigerants are concerned), have your system control (excluding portable air conditioning) by a professional every two years is recommended;
– good ventilation is also necessary to avoid stagnation of air and reduce the risk of viral transmission;
– operate the device on “all new air”, not on “partial recycling or total air”;
– It is also recommended to drink regularly in order to compensate for dryness -related drying.
In summary, “air conditioning does not cause disease directly, reassures Dr. Frédéric Le Guillou, But some factors such as poor maintenance, too dry air or individual sensitivity can cause various symptoms. People allergic, asthmatic or damage to respiratory problems must redouble vigilance, because they are more sensitive to it. »»
Note : a decree of the ministers responsible for construction and energy defines the Cooking conditions of cooling systems. In the premises in which a cooling system is installed, it should only be put or kept in operation when the interior temperature of the premises exceeds 26 ° C.
To learn more about vulnerable people with regard to air quality: France respiratory health
Source : Interview with Dr. Frédéric Le Guillou, president of the Association Health Respiratory France (July 02, 2025); UFC Que Choisir (accessed 07/02/25); Health.gouv.fr (accessed 07/02/25)
