For many people, air conditioning is the ultimate summer luxury. It turns stifling rooms into cool refuges, taming both heat and humidity. But here’s the part we don’t talk about enough—if your AC isn’t properly maintained, it can quietly turn into a delivery system for illness.Researchers and health professionals have been warning about the connection between malfunctioning or poorly cleaned AC systems and a condition known as Sick Building Syndrome (SBS). The symptoms may seem mild at first—headaches, coughing, skin irritation—but in some cases, they can signal exposure to harmful bacteria, fungi, and even viruses circulating in your building’s air. This isn’t about making you afraid of AC—it’s about understanding the risks so you can keep the benefits without the downsides.What Is Sick Building Syndrome?Sick Building Syndrome is a catch-all term for symptoms that develop when you spend long periods in a particular indoor environment—especially one that relies heavily on air conditioning. The symptoms can vary, but common complaints include:Persistent cough or wheezeRunny or congested noseHeadaches and dizzinessFatigue or trouble focusingSkin rashes or irritationOne hallmark of SBS is that the symptoms tend to ease once you leave the building and worsen when you return. While it’s most common in office workers, it can happen in any air-conditioned space, from hospitals to hotels.A 2023 study from India provided some of the strongest evidence yet that prolonged exposure to air-conditioned environments can affect health. The researchers tracked 400 healthy adults—half working six to eight hours a day in AC offices, half in non-AC settings—over two years.The results were striking: the AC group had more SBS symptoms, more allergies, and poorer lung function. They were also absent from work more often. These findings match earlier studies showing higher SBS prevalence among office workers in climate-controlled buildings compared to those in naturally ventilated spaces.How AC Systems Become a Health Risk?When air conditioners are working the way they should, they clean airborne impurities and control temperature and humidity. The problem arises when they are not regularly serviced or cleaned. Issues may involve:1. Bacterial GrowthOne of the greatest threats is Legionella pneumophila, the bacteria that cause Legionnaires' disease. This acute lung infection is transmitted when individuals breathe in small droplets of water with the bacteria on it. AC cooling towers, particularly for large buildings, are perfect breeding grounds if they are not well maintained.They exhibit pneumonia-like symptoms—fever, cough, chest pain—and develop two to 14 days after becoming infected. In extreme situations, Legionnaires' disease can be life-threatening.2. Fungal ContaminationMoisture and dust accumulation within AC systems provide ideal environments for fungal growth. In studies conducted within hospitals, fungi such as Aspergillus and Cladosporium were isolated in ventilation ducts. These fungi are potentially lethal for immunocompromised individuals, transplant patients, or premature infants.Fungal infection may result in prolonged cough, loss of weight, and in some instances, extend beyond the lungs to the brain, kidneys, and other organs.3. Viral TransmissionEven though most viruses are transmitted through person-to-person contact, air conditioners can, in specific circumstances, act as a source of airborne viral outbreaks. One case in point was in a Chinese kindergarten, where an outbreak of norovirus infecting 20 children was traced to the AC system in a bathroom.Surprisingly, properly serviced AC systems can also minimize viral transmission, such as COVID-19, by filtering the air effectively—testimony that maintenance is the defining difference between protection and risk.What Is the Role of Humidity?Even if your AC is freshly cleaned, there's another sneaky way it can influence health: dehumidifying the air. Air conditioners tend to reduce indoor humidity to levels that can parch your nasal and throat membranes. These mucus membranes form part of the natural defense system of your body, catching and flushing out germs before they enter deeper tissues.When they evaporate, they're not as effective, potentially allowing bacteria or fungi to more easily cause sinus or respiratory infections.Should You Get Rid of Air Conditioners Completely?It's worth noting that air conditioning itself is not necessarily dangerous—indeed, in extreme temperatures, it can be a matter of life and death. Research indicates that AC prevents heat-related illnesses and fatalities, particularly among susceptible populations such as the elderly.The issue isn't the technology—it's how we use it. Neglected systems can turn a comfort into a disease machine. Properly maintained ones can clean indoor air, cut down on allergens, and help hot weather feel less oppressive.All but a few AC-associated health hazards are avoidable with regular maintenance. That entails:Replacing or cleaning filters as the calendar dictatesServicing cooling towers and water systems to avoid Legionella growthInspecting ducts for mold and dust buildup on a regular basisMaintaining humidity levels within a healthy limit (preferably 40–60%)Missing out on these steps not only impacts air quality but can also cause your AC to work harder, wasting energy and reducing its lifespan.How to Stay Safe?If you spend a lot of time or work in an air-conditioned building, take note of your symptoms. If you notice an improvement when you are out of the building, it's worth bringing the matter to management or facilities personnel. In workplaces, maintenance of HVAC (heating, ventilation, and air conditioning) is usually a joint duty between employers and building owners.At home, have professional maintenance at least annually, replace or clean filters as frequently as the manufacturer recommends, and clear vents of dust and debris. If your AC has a built-in humidifier, track indoor humidity levels.Air conditioning doesn’t have to make you sick but without proper care, it can. Sick Building Syndrome is real, and while it’s not always caused by AC, neglected systems can be a major contributor. The fix isn’t to ditch cooling entirely it’s to treat the system in your home or workplace like the important health safeguard it can be when maintained correctly.