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Can air conditioning make you ill?

Have you ever wondered if your air conditioner has, or possibly could, make you ill?  If so, read on.

“Air conditioning sickness” is a term that you may feel like you’ve experienced at some point.  Cooped up indoors, slaving away, and aircon pumping, when all you want to do is be out in the fresh, warm air.  You may wonder if this “sickness” a mental state or actual physical illness.

It isn’t uncommon to suspect air conditioning as a contributing factor or even cause of acute or chronic illness.  With us spending 90% of our time indoors on average, it makes sense to look to the device circulating air in that environment.  However, the relationship between air conditioning and health is not as black and white as you may think.

Air conditioning and ill couple

Air conditioning is just one possible cause of illness.  In fact, it can also help improve your health in many ways.  Some of the ways that an HVAC system can help improve your health includes, but is not limited to:

  • Air filtration,
  • Air purification,
  • Humidity and moisture control,
  • Thermal comfort,
  • Fresh air intake and provision,
  • Ozone removal,
  • Pollutant removal, and
  • Exhaust ventilation.

To ensure the best health outcomes, maintenance is key in many ways.  Design and usage also have a major influence on how air conditioning can affect your health.  We will explore some of the common issues surrounding air conditioning and your health.

Indoor Air Quality

Poor indoor air quality is obviously concerning for any organisation, business or home owner.  The World Health Organization (WHO) has suggested that up to 30% of new or renovated buildings may have inadequate indoor air quality.  The rates is even higher for old and neglected buildings.

Poor air quality has been linked to reduced productivity in offices and impaired learning in schools.  Even worse, it’s been linked to a phenomenon known as “sick building syndrome”, where a building people live or work in results in illness or chronic disease.

Indoor work spaces are found in many different commercial environments including offices, high-rise buildings, hospitals, schools, and childcare facilities, and even at home in light of the COVID-19 pandemic.  These workplaces do not typically involve hazardous substances or tasks, yet occupants can still suffer from sick building syndrome.

Sick woman because of poor air quality

Causes of sick building syndrome in homes or businesses, excluding any obviously hazardous substances or activities, can include but is not limited to:

  • Poor building design,
  • Poor heating, ventilation and air conditioning (HVAC) design,
  • Insufficient fresh air intake,
  • Inadequate air filtration,
  • Inadequate exhaust ventilation,
  • Neglected building maintenance,
  • Infrequent air conditioner maintenance,
  • Use of light industrial/cleaning chemicals,
  • Excessive moisture,
  • Presence of mould,
  • Presence of volatile organic compounds (VOC’s), and
  • Production of contaminants from outgassing (i.e. the release of a gas that was absorbed/dissolved/trapped in certain building materials).

Individual illness can be complex and rarely attributed to a single cause.  Investigation of all possible causes is warranted, including workplace infrastructure, usage and interactions, home design and equipment, hobbies and activities, and psychological and mental factors, just to name a few.

Can air conditioning make you sick?

People often wonder if their air conditioner is making them sick.  While air conditioners themselves are not harmful to your health, specific conditions and interactions with the indoor environment can make you sick.

There is good reason to be concerned by anything that either fails to help control the growth of, or at worst promotes the growth of, microbial contaminants such as bacteria and mould as well as mildew and fungi.  Pollutants in the air and overall indoor air quality are also major areas of focus when looking at air conditioning and your health.

Building and HVAC System Design

Indoor air quality should be a key consideration in the design and construct of a building.  The design and installation of a residential or commercial HVAC system is a major component of any building.  Ventilation as one key component of the HVAC system that helps to ensure healthy air quality.

Ventilation refers to the introduction of outdoor air into an indoor space in an intentional way.  This can be done mechanically, naturally, or via a combination of the two methods.

Ventilation is typically used to displace and/or dilute indoor pollutants, but can also impact air motion, humidity, and temperature.  These factors all impact health in terms of air quality, thermal comfort, mental health and overall satisfaction with the indoor environment.

Mechanical ventilation is often integrated with the air conditioning equipment used to heat or cool the interior of a building.  It can include air being pushed into a building (supply fans), drawn out of building (exhaust fans), or combination of both.

Ventilation systems can also consist of features such a carbon dioxide (CO2) sensors and ozone detection devices.  These features are designed to improve the indoor air and help further reduce the risk of illness.

Mechanical ventilation in buildings


If there are higher than normal levels of pollution inside, then the ventilation of outside air will need to occur at a higher rate.  Interestingly, classroom have greater ventilation requirements and standards compared to indoor environments containing mostly adults only.  The condition of the outside air is another factor that must be considered (think smoggy city air vs fresh country air…).

Humidity control and moisture management are critical factors dependent on correct HVAC system design.  High humidity outside requires special attention to ensure suitable levels are maintained inside.  High humidity and moisture can promote the growth of mould, which is associated with a high prevalence of respiratory conditions.

Furthermore, an air conditioning system may need to include “make up air” to replace what is removed from the internal space.  Overall, an HVAC system should be balanced to ensure a healthy indoor environment and health promotion, rather than risking the promotion of illness or spread of disease.

Building Maintenance

If your indoor environment is not maintained, it can become the ideal environment for illness-inducing bacteria and mould to grow.  These nasties can then be circulated by an air conditioner.

Regular cleaning and maintenance is vital to help ensure the indoor environment, combined with the aircon, doesn’t make you sick.  This includes removing clutter/unused items (aka dust-collectors), dusting, wiping down surfaces, disinfecting, vacuuming carpets/rugs, and mopping.

If your residential or commercial air conditioning maintenance is not adequate, the air conditioning system can spread illness-causing particles and pathogens already present in the indoor environment.  Obviously this is not something that anyone wants to experience!

Moisture, damp and high humidity levels in your home or workplace can also lead to range of health issues and illnesses.  Unwanted water can cause wood to rot, fungi to grow, and a range of mould issues.  Once airborne, mould spores can be inhaled and certainly make you sick.

Dust mites can also find a nice, cosy home in damp, humid areas of a building.  These can trigger a range of negative health outcomes in people, especially those with underlying immunological conditions.

Structural dampness can also promote the presence of bacteria in an indoor environment, as bacteria require water to grow and multiply.  This leaves occupants of such a building at risk of bacterial infections when spread around room.

Air conditioners can exacerbate but also help moisture issues.  As mentioned, an aircon can circulate existing mould and bacteria around an indoor space.  However, air conditioning can also assist in drying out the interior of a home or business premises.  While they obviously cannot treat the underlying cause of dampness, air conditioners can help keep unwanted moisture at bay.

Air Conditioner Maintenance

Air conditioners themselves can actually be a source of disease if proper air conditioner maintenance is neglected.  If not cleaned and serviced on a routine basis, bacteria and mould can start to grow.

Condensation is produced in an air conditioner unit as air passes over the evaporator (indoor) coil.  This moist, dark environment can make a perfect home for mould, bacteria and other organic matter to grow.  Dust entering the AC system can further support their growth, acting as food for microorganisms.

As air is blown out from an air conditioner, any illness-causing matter is blown out into the room.  This matter is circulated as part of the air conditioning air flow cycle and can make you sick.

Air filters are one line of defence in stopping dust reaching the wet coils.  As their name suggests, they filter the air before it reaches the indoor air conditioning unit.  Regular checking, cleaning and replacing of filters when required is vital to ensure aircon health as well as human health.

Another area of concern is gas leaks that can develop if the home or commercial air conditioner service has not carried out routinely as required.  Refrigerant gas in air conditioning systems is usually in the form of a chlorofluorocarbon (CFCs) or hydrochlorofluorocarbons (HCFCs).  These gases can be harmful to human health as well as the environment.

Building and Air Conditioner Use

Building HVAC systems must be used as intended in order for them to function as designed.  Otherwise, system and human health can be compromised.

In some parts of the world (including southern states and territories of Australia, Europe and parts of the USA), outdoor air temperatures can be cool enough at times during the year where air doesn’t need cooling further to provide thermal comfort indoors.  This impacts how the air conditioning system is used and the amount of make up air entering the internal environment.

Air circulation

Infiltration is another factor at play that may be used in a commercial buildings and occasionally in residential settings.  A building may be kept under slightly positive air pressure, compared to outside pressures, in order to reduce infiltration.  This can help with moisture management and humidity control in that particular building.

Dilution of indoor pollutants, is another HVAC system usage consideration, but is dependent on the quality of outside air.  One example is ozone.

Ozone is highly reactive with many chemicals found indoors, which reduces the concentration in the air once it enters a building.  However, the products of the reaction between ozone and many indoor pollutants includes organic compounds that can be even more damaging to health and cause serious illness and disease.

Woman coughing sick in office

Another common cause of air conditioning sickness described earlier is running an air conditioner at temperatures lower than recommended.  23 – 24 degrees is recommended for most commercial office spaces.

When you run an air conditioner too cold, viruses can thrive and then be spread around a room.  The common cold-causing virus is just one example.  Such viruses survive best in cold, low-humidity environments created by the aircon being run at a undesirably low temperature.

Excessively cold temperatures can also affect blood flow in the body.  The body naturally constricts arteries in the skin to protect from heat loss.  As a result, blood flow is decreased and this can negatively affect your health.

Decreased blood flow also reduces the circulation of white blood cells.  White blood cells help protect the body against viruses and other threats to the body.  Therefore, less white blood cells results in lower immunity and leaves the body more susceptible to infection and illness.

A very cold indoor environment can also lead to shivering.  Long-term shivering is associated with a whole range of issues, including fatigue, headaches, and muscle and joint soreness.  It can also cause a general run down of body systems, leaving you feeling tired, lethargic, and worn out.  This is clearly not a state anyone wants to be in.

Running an air conditioner to the extreme can also create a dry environment.  Dryness evaporates moisture from the body, which increases risk of dehydration.

Drying out the lining of the nose makes the body more susceptible to infection.  Drying of the skin can also lead to a range of skin conditions.  Both outcomes reduced human health and can make you sick in one way or another.

There are many factors involved in the relationship between air conditioning and illness.  Design is vital in promoting health from the very beginning.  From there, building and air conditioner maintenance is vital for ensuing HVAC systems are working as designed and not circulating illness-causing matter or micro-organisms.

Correct usage of air conditioning equipment is also important to help reduce the chance of getting sick.  Routine air conditioner servicing, cleaning and repairs is vital to ensure a healthy indoor environment.

For assistance in your home or workplace with installation or maintenance of HVAC equipment, please don’t hesitate to contact us.