The most well-known and serious disease linked to air conditioning is Legionnaires' disease. It is a severe type of pneumonia caused by Legionella bacteria that thrive in warm, stagnant water and can be spread through the cooling towers of large commercial HVAC systems.
Air conditioning sickness—often linked to Sick Building Syndrome—occurs when extended exposure to artificially cooled environments, poor ventilation, or unmaintained AC units triggers adverse physical reactions.
The first signs of Legionnaires’ disease typically appear 2 to 14 days after exposure to Legionella bacteria. Early symptoms are often flu-like and include:
Legionnaires' disease mostly involves the lungs. But it can cause infections in sores and in other parts of the body, including the heart. A mild form of Legionnaires' disease, called Pontiac fever, can cause fever, chills, headache and muscle aches. Pontiac fever doesn't infect the lungs.
Legionnaires' disease is not contagious. You cannot catch it from another infected person, coughing, or sneezing. Instead, it is contracted by inhaling aerosolized mist or water droplets containing Legionella bacteria.
Legionnaires' disease symptoms usually develop 2 to 14 days after exposure to Legionella bacteria, but it can take longer. The symptoms of Legionnaires' disease are similar to other types of pneumonia. Symptoms include: Cough.
Legionnaires’ disease is an acute respiratory infection caused by Legionella bacteria. To combat it, you need medical intervention to eliminate the bacteria inside the body, and environmental maintenance to kill the bacteria in water sources.
Air conditioning systems, especially centralized installations and large building ventilation units, provide ideal environments for the growth of Legionella bacteria, which causes Legionnaires' disease.
Most people with Legionnaires' disease will need hospital care but will fully recover with treatment. The sooner you get treatment, the less likely you are to develop serious complications. The most common treatment is antibiotics.
Mold sickness usually presents as persistent, allergy-like symptoms. Common signs include a runny or stuffy nose, sneezing, coughing, wheezing, and itchy, watery eyes. Symptoms may worsen indoors, linger longer than a typical cold, and can also include skin irritation, headaches, or triggered asthma attacks.
Legionella bacteria primarily cause two distinct illnesses, collectively known as legionellosis:
Legionnaires' disease is usually contracted by breathing in small, contaminated water droplets (mist or aerosol) that contain Legionella bacteria. It is not spread person-to-person.
Legionnaires' disease symptoms typically develop 2 to 10 days (but sometimes up to 14 days) after exposure to the Legionella bacteria. In most cases, the initial flu-like signs and pneumonia symptoms appear within 5 to 6 days.
Some people feel a burning sensation in their eyes, nose, ears, lips, or tongue. More serious symptoms include difficulty breathing, severe pain in the nose or throat, vision loss, irregular heartbeat, fainting, vomiting or diarrhoea, blood in vomit or stool, and severe stomach pain.
The 3-minute rule requires waiting at least three minutes after an air conditioner shuts off before turning it back on. This pause allows refrigerant pressure inside the system to equalize. Restarting too quickly forces the compressor to work against high pressure, which can cause severe mechanical strain, blown fuses, and permanent compressor damage.
The Rule of 5000 Rule is simple: Multiply the cost of the needed repair by the age of your air conditioner. If the result is greater than 5000, AC replacement is generally the smarter choice. If it's less than 5000, a repair might still be worth the investment.
Urine mycotoxin tests are ideal for testing yourself (and your family members) for mycotoxin exposure. They're absolutely painless, totally non-invasive, and incredibly easy to use. With just a small amount of urine, our experts will be able to spot up to 15 different illness-causing mycotoxins.
Exposure to indoor Alternaria can lead to various health issues, especially in individuals with allergies, asthma, or weakened immune systems. Symptoms may include sneezing, coughing, itchy eyes, and skin rashes. In severe cases, it can trigger asthma attacks or lead to chronic respiratory problems.
If you suspect your house is making you sick, track if your symptoms improve when you are away from home for a few hours or on vacation. Common culprits include mold, poor ventilation, carbon monoxide, or VOCs, which trigger issues ranging from allergies to chronic fatigue.
Legionnaires' disease is most often caused by Legionella pneumophila. You get Legionnaires' disease when the bacteria infect your lungs. Legionella is found naturally in lakes, streams and soil, but it can also contaminate drinking water and air systems, especially in large buildings.
Legionella bacteria are killed through specific physical and chemical methods, primarily focusing on extreme temperatures and strong disinfectants.
The initial symptoms of Legionnaires' disease are similar to those of flu:
Dirty air conditioning systems are most commonly linked to Legionnaires' disease, a severe form of pneumonia caused by Legionella bacteria. Other risks include Pontiac fever (a milder flu-like illness) and worsening of allergies or asthma due to circulating mold and dust.
Clostridioides difficile (klos-TRID-e-oi-deez dif-uh-SEEL) is a bacterium that causes an infection of the colon, the longest part of the large intestine.
Common Types of Molds Found in HVAC Units
The most frequently found molds in HVAC systems include: Cladosporium – Typically black or green, usually grows on damp fabrics or wood. Aspergillus – Found indoors and can become airborne, potentially triggering allergic reactions.