9 Ways Your Air Conditioner Might Be Making You Sick

By Michael Franco

May 12, 2025

Air conditioning is a lifesaver during hot weather, keeping homes cool and comfortable. However, if you’ve ever noticed feeling unwell after spending a lot of time in an air-conditioned space, your AC unit might be to blame. Poorly maintained air conditioning systems, extreme cold temperatures and poor indoor air quality can contribute to a range of health issues.

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Symptoms of 'Air Conditioner Sickness'

If your air conditioning system is causing health problems, you may experience symptoms such as:

  • Dry, itchy throat or nasal passages

  • Coughing or wheezing

  • Sinus congestion or headaches

  • Dry or irritated skin

  • Fatigue or dizziness

  • Increased allergy symptoms

  • Respiratory issues, such as shortness of breath

These symptoms can be mild or severe, depending on how long you’ve been exposed to poor indoor air quality and how well your air conditioning system is maintained.

How Your Air Conditioner Can Make You Feel Sick

1. Poor Ventilation and Stale Air

Air conditioners circulate air within a closed environment, and without proper ventilation, contaminants can build up over time. This can lead to what’s known as Sick Building Syndrome, where people experience symptoms like headaches, fatigue and respiratory discomfort due to prolonged exposure to stale, polluted air.

Fix It: Periodically open windows to let in fresh air and use exhaust fans in kitchens and bathrooms to improve air circulation.

2. Mold and Bacteria Growth in Your AC

Your air conditioning unit can become a breeding ground for mold, mildew and bacteria, especially if moisture accumulates in the system. When these contaminants are circulated through the air, they can cause respiratory problems, allergies and even infections.

Fix It: Regularly clean air intake grates and schedule professional maintenance to prevent mold buildup inside your AC unit.

3. Dirty Air Conditioner Filters and Poor Indoor Air Quality

Air filters trap dust, pollen and other airborne particles, but if they aren’t replaced regularly, they can become clogged and spread these irritants throughout your home. This can lead to breathing problems and worsen allergy symptoms.

Fix It: Change air filters every one to three months and consider using HEPA filters to improve indoor air quality.

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4. Extremely Low Temperatures

Spending long hours in an air-conditioned environment set at a very low temperature can cause your body to react negatively. Cold air can dry out your skin and mucous membranes, leading to a sore throat, sinus irritation and an increased risk of colds or respiratory infections.

Fix It: Keep your AC at a comfortable setting — ideally between 72 and 78 degrees Fahrenheit (22 and 26 degrees Celsius)—to prevent extreme cold air from affecting your health.

5. Lack of Humidity and Dry Air

Air conditioning removes moisture from the air, which can lead to overly dry indoor environments. This can cause dehydration, irritated eyes, dry skin and respiratory discomfort.

Fix It: Drink plenty of water throughout the day and use a humidifier if your indoor air feels too dry.

6. Spread of Dust and Allergens

If your air conditioner is not properly maintained, it can distribute dust, pet dander and other allergens throughout your home. This can trigger allergy symptoms, such as sneezing, congestion and itchy eyes.

Fix It: Dust and vacuum regularly and use an air purifier to help filter out allergens.

7. Chemical Exposure from Air Conditioner Components

Some air conditioning systems release volatile organic compounds from certain materials, including insulation, adhesives and cleaning products used on the unit. Long-term exposure to these chemicals can cause headaches, dizziness and respiratory irritation.

Fix It: Use non-toxic cleaning products and ensure your home is well-ventilated to reduce chemical buildup. If your HVAC system is newly installed, run it for a few days with your windows cracked to allow VOCs to dissipate.

8. Carbon Monoxide Leaks from HVAC Systems

If your air conditioning system is connected to a furnace or fuel-burning appliance, a malfunction could lead to carbon monoxide leaks. Carbon monoxide poisoning is dangerous and can cause symptoms like nausea, dizziness and confusion.

Fix It: Install carbon monoxide detectors in your home and schedule regular HVAC maintenance to prevent leaks.

9. Recycled Air Spreading Viruses and Bacteria

Air conditioners recirculate air, which means that if someone in the house is sick, the AC system can help spread germs and viruses to other areas. This can increase the likelihood of catching colds, flu or other airborne illnesses.

Fix It: If someone is sick, keep your home well-ventilated, disinfect frequently touched surfaces and change AC filters to reduce airborne contaminants. Keeping a few windows slightly open can help as well.

Your Health Depends on the Health of Your AC Unit

By taking these precautions, you can continue to enjoy the comfort of air conditioning without compromising your health. A well-maintained air conditioning system should improve indoor air quality and create a healthier environment rather than making you feel sick. If you notice persistent symptoms, it may be time for a professional to inspect your HVAC system and improve ventilation in your home.

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