We all understand the comfort that air conditioning can provide in Australia’s extreme temperatures. However, it can also offer other benefits like providing clean air, controlling humidity and helping to maintain our body temperature. 

But can air conditioning make you sick? And if so, how can it be avoided? 

Air conditioning at home

Unless regularly cleaned, air conditioners can become a breeding ground for a range of bacteria and fungi due to the moisture they produce. In fact, one study found that the average fungal contamination inside air conditioners was over five times greater than that found in carpets1. It also found that air conditioners commonly had penicillium and cladosporium colonies, both of which can make us sick if inhaled over long periods. 

More common health issues relate to the growth of mould in air conditioning units. Mould thrives in damp, dark conditions, reproducing and spreading quickly once established. If the mould is allowed to remain, it ends up being pumped out into the air by the air conditioning unit, and can result in various health effects and conditions. These include: 

  • Sneezing
  • Coughs
  • Wheezing
  • Earaches
  • Stomach bugs
  • Dry, itchy skin
  • Irritated nasal passages
  • Infections
  • Allergies
  • Asthma
  • Watery or dry eyes

Can sleeping in air conditioning make you sick? While leaving your AC at night won’t make you ill, it can still impact us physically by resulting in: 

  • A too-low body temperature – our core temperature falls overnight as part of our body’s natural rhythm, which allows us to tolerate slightly higher temperatures than we would during the day. It’s recommended to slightly increase the set temperature of your air conditioner to prevent your core temperature dropping too low.
  • Dry skin, throat and mouth – conditioned air is drier than usual, and can pose dental issues such as tooth decay or other oral diseases. 
  • Hormonal effects – when you sleep, your body repairs itself, including the production of restorative hormones. A core temperature that is too cold reduces our body’s ability to produce the raw materials it needs to boost our immunity and ward off bugs and bacteria.

Air conditioning at work

Can central air conditioning make you sick at work? The answer is a definitive “yes” according to experts, citing the common health concern, Sick Building Syndrome (SBS) as proof. SBS refers to people suffering from illness or becoming infected with chronic disease due to the building where they work or live, and it is most prevalent in larger office buildings with central air conditioning units. 

According to a study in the International Journal of Epidemiology2, occupants who worked in air conditioning buildings reported more symptoms of ill health than those who worked in buildings with natural ventilation. Symptoms included: 

  • Fatigue
  • Nausea
  • Dizziness
  • Headaches
  • Respiratory issues like coughs
  • Nose, eye and throat irritations

Experts believe the symptoms are caused by allergens, irritants, and toxins in the AC units, which are attracted by moisture.

In terms of viruses, influenza is not spread through ventilation or air conditioning systems, however experts are still unsure about the potential for the airborne transmission of COVID-19. QUT’s Director of the International Laboratory of Air Quality and Health Professor, Lidia Morawska, recommends that during epidemics, you should avoid having air conditioners on recirculation mode as it can potentially bring back the virus into supplied air.

How to avoid getting sick

Air conditioning at home

Filters should be cleaned every one to two months, and a professional AC servicing undertaken at least once a year, although before the start of summer and winter is highly recommended. Your air conditioner also needs to be serviced if: 

  • The temperature is inconsistent – your air conditioner isn’t providing a consistent air temperature at the nominated setting.  
  • Your energy bills are increasing — fluctuations in energy costs often occur in peak hot and cold periods, however if your energy costs are consistently high, an energy audit may provide more insights.
  • It is making strange noises an unusually loud unit may be a sign the fan isn’t working correctly, a part has become loose, or an internal mechanism is clogged by dirt or mould.
  • It is producing strange smells — this could be a sign that a filter needs replacing.
  • There is evidence of dripping water — depending on the type of unit you have, water dripping from your outdoor unit may be normal, but moisture inside the house should be investigated.

Air conditioning at work

While Sick Building Syndrome encompasses a multitude of non-specific systems, building-related illnesses (BRI) comprise specific, diagnosable symptoms caused by agents like bacteria, fungi and even chemicals. There are usually four causal agents in BRI — immunologic, infectious, toxic and irritant.

In many cases, merely improving indoor air quality (IAQ) can reduce or even eliminate people’s continual exposure to toxins. In terms of air conditioning systems, building managers or body corporates can instigate:

  • Regular inspections to indicate the presence of mould or other toxins.
  • The adequate maintenance of all building mechanical systems.
  • The proper and frequent maintenance of existing HVAC air cleaning systems.
  • The installation of HVAC systems or devices to remove VOCs and bioeffluents (the atmospheric pollutants emanating from the bodies of humans or animals).
  • Most importantly, regular servicing from a professional.

Reap the benefits

If your air conditioning unit is cleaned well and maintained regularly, then you will be able to take full advantage of its health benefits. These include:

  • Assisting with respiratory conditions like asthma – by removing pollutants from the air so you can breathe easier. 
  • Alleviating sinus issues and other allergies – a clean filter will trap airborne particles.
  • Helping prevent heat stroke and other heat-related conditions – they can provide relief in high temperatures including from heat rashes.
  • Relieving arthritis by keeping joints warm – a warm room can help keep sufferers’ joints moving and alleviate pain. 


  1. Nobuo Hamada, Tadao Fujita, 2002, Effect of air-conditioner on fungal contamination, Science Direct
  2. Mark J Mendell, 2004, Commentary: Air conditioning as a risk for increased use of health services, International Journal of Epidemiology