Air-conditioning systems are widely used in homes, workplaces, and public spaces. Proper use of air conditioning provides thermal comfort and helps reduce exposure to high temperatures. Improper use and maintenance, however, may affect indoor air quality and may be associated with the occurrence or worsening of certain health symptoms.

Indoor air quality depends on temperature, relative humidity, ventilation, the presence of pollutants, and the maintenance of air-conditioning systems. Poorly maintained systems, the accumulation of dust and moisture, and microbiological contamination may contribute to exposure to particles, allergens, and biological agents.

Particular attention is needed for children, people aged ≥65 years, pregnant women, immunocompromised individuals, and people with chronic respiratory and cardiovascular diseases.

Air Conditioning and the Workplace

In workplaces, improper use or maintenance of air-conditioning systems may affect temperature, relative humidity, ventilation, and indoor air quality.

These factors, together with other conditions related to the indoor environment, may contribute to the occurrence of so-called “sick building syndrome” – a group of nonspecific symptoms such as headache, fatigue, irritation of the eyes, nose and throat, and respiratory discomfort, which are associated with spending time in a particular building and usually improve after leaving it.

Excessive cooling, low relative humidity, and direct exposure to cold air currents may cause irritation of the eyes and mucous membranes of the upper respiratory tract and may worsen symptoms in people with existing respiratory diseases. Increased humidity, condensation, and inadequate maintenance of systems may allow mold and other biological contaminants to develop.

When there is a large difference between the indoor and outdoor temperatures, gradual acclimatization before going outside is recommended. If possible, at least 15 minutes before leaving an air-conditioned space, reduce the cooling intensity or spend some time in an area with a temperature closer to the outdoor temperature.

Benefits of Using Air Conditioning

·         Reducing exposure to high temperatures and the risk of heat-related health effects;

·         Maintaining thermal comfort during work and rest;

·         Maintaining work capacity, concentration, and productivity during high temperatures;

·         Reducing excessive sweating and fluid loss;

·         Reducing the concentration of certain particles and allergens in the air when appropriate and properly maintained filtration systems are used;

·         Reducing exposure to outdoor noise when windows are closed.

Possible Adverse Health Effects

Improper use and maintenance of air-conditioning systems may be associated with:

·         Dryness and irritation of the mucous membranes of the nose and throat;

·         Dry, irritating cough, sneezing, nasal congestion, and other upper respiratory symptoms;

·         Worsening of symptoms in people with chronic rhinitis, sinusitis, asthma, and other chronic respiratory diseases;

·         Dryness and irritation of the eyes and increased discomfort in people who wear contact lenses;

·         Headache, fatigue, and general discomfort;

·         Muscle stiffness and pain following prolonged direct exposure to cold air currents;

·         Allergic and respiratory reactions following exposure to dust, mold, and other biological contaminants.

Air conditioning itself does not cause colds, influenza, or other respiratory infections. Transmission of respiratory infections indoors depends on several factors, including ventilation, the number and proximity of people present, and the duration of exposure. Improper maintenance of air-conditioning systems, particularly when conditions allow water and moisture to accumulate, may enable microbiological contamination and affect indoor air quality.

Important to Remember

Air-conditioned rooms should be ventilated regularly.

During hot summer days, it is recommended to maintain the temperature in air-conditioned rooms at around 25 °C, while avoiding excessive cooling.

When there is a large difference between indoor and outdoor temperatures, gradual temperature acclimatization for at least 15 minutes before going outside is recommended.

Relative humidity should preferably be maintained between 40% and 60%, while avoiding conditions that lead to condensation and mold growth.

Direct and prolonged exposure to cold air currents should be avoided.

Filters should be cleaned or replaced regularly according to the manufacturer’s recommendations.

Air-conditioning systems should be serviced regularly, especially before periods of intensive seasonal use.

Installation, servicing, and maintenance of the systems should be carried out by appropriately qualified personnel.