The connection between air conditioning and developing a persistent, dry cough is real. While AC does not cause infectious illness, it changes the air’s physical properties and distributes irritants, triggering a cough reflex. The cooling process lowers the air temperature and significantly reduces the humidity level. These environmental changes, along with the unit’s cleanliness, cause many people’s respiratory systems to react to conditioned air.
The Respiratory Impact of Cold, Dry Air
AC units remove moisture as they cool the air, creating a low-humidity environment that affects the respiratory tract. The mucosal linings in the nose and throat rely on moisture to properly filter and warm the air we breathe. Exposure to dry air dehydrates this protective layer, causing irritation and increased sensitivity that triggers a cough reflex. The body may compensate for this dryness by producing more mucus, which can also lead to a cough.
The low temperature of the air also contributes to the problem, especially for those with sensitive airways or pre-existing conditions like asthma. Inhaling cold air can cause bronchoconstriction, a narrowing of the small airways leading to the lungs. This constricting action is a protective mechanism, but it can lead to symptoms such as chest tightness, wheezing, and a dry, hacking cough. This effect is similar to breathing cold outdoor air, simply recreated indoors by the AC system.
Airborne Irritants and Contaminants from AC Units
Beyond the air’s physical properties, AC system components can become a source for airborne irritants. Cooling coils and drainage pans collect condensation, creating a damp environment ideal for biological growth. This stagnant moisture fosters the development of mold, mildew, and bacteria. When the AC runs, it can aerosolize and circulate these biological agents and their spores throughout the indoor space.
Air filters and ductwork that are not cleaned regularly accumulate common household allergens like dust, pollen, pet dander, and dust mites. A saturated filter can no longer trap particles effectively, blowing a high concentration of irritants into the room. For individuals with allergies, inhaling these concentrated contaminants provokes irritation, resulting in a persistent cough or aggravating existing conditions. In rare cases, exposure to mold or bacteria from a contaminated unit can cause hypersensitivity pneumonitis, sometimes called “air conditioner lung.”
Practical Steps for Prevention and Relief
Addressing an air conditioning cough involves maintenance and environmental control. To counter dry air, introduce a humidifier to maintain indoor humidity between 40% and 50%. Adjusting the thermostat to a slightly warmer setting also reduces the dehydrating effect of the cooled air. Staying well-hydrated helps keep the body’s mucosal linings moist and resistant to drying effects.
Regular maintenance of the AC unit is necessary to address airborne contaminants.
Filter Management
The air filter should be inspected and replaced or cleaned every one to three months, depending on the filter type and usage, to effectively capture dust and allergens. Consider using a high-efficiency particulate air (HEPA) filter or an air purifier to capture smaller airborne particles that pass through standard AC filters.
Professional Cleaning
Scheduling professional cleaning of the coils and ductwork is important to remove built-up mold, mildew, and debris that cannot be reached through routine filter changes.