Why air conditioning units can make your premises smell, from London Cool

Colleagues at our head office in Crawley, West Sussex RH10  have been discussing smells recently!

Possibly we should get out more, but it is true that air conditioning systems can give off smells, evidenced by recent reports which have highlighted an increase in the number of room air conditioning units giving out a bad smell.  Research has shown that one reason for the bad smells in installed air conditioner systems is a rather disgusting one – dead skin! 

Scientists have discovered that the stench from smelly air conditioner systems is caused by dead skins cells that our bodies shed which are then trapped in room cooling units, air conditioner filters and coils.  Bacteria that live in air conditioning units survive by eating dead skin cells. With each person shedding approximately 8lbs of dead skin cells each year, these are rather well fed bacteria.  

From our offices we serve London and the South East.  We have looked at our air conditioning call outs, especially for companies that have no air conditioning maintenance contracts or service contract visits for installed air conditioning.  A lot of the call outs for breakdowns or air conditioner smells are due to poor maintenance or understanding how room air conditioners work.  Dead skin will get into air conditioner systems and if this skin or hair also has perfume, aftershaves, hair or skin conditioners then this will add to the amount caught in room air conditioners’ filters and coils and increase the potential for installed air conditioning systems to give off odours.

Now here comes the science bit . . . dead cells contain keratin, a structural protein which makes up fingernails and hair in humans.  In room air conditioning units, the bacteria that live there contain chemicals called keratinases.  When the keratinase chemicals digest the skin cells, the keratin is broken down and produces ammonium which is circulated by the air conditioning unit - spreading the smell of urine.  

Proteins make up a large portion of the human diet and are converted to ammonium after they are broken down in the liver.  As it passes through the liver, ammonia is converted to ammonium and then to urea - the main ingredient in urine – with its very distinctive smell.

You don’t need to be a scientist to realise that any air conditioning units which are home to the bacteria are likely to make your whole house, car or office smell like urine.  With a lot of air conditioner smell call-outs, people will say their air conditioning smells of cat urine – which seems pretty unfair to cats!  Other chemicals found in human skin cells - eg lipids and triglycerides - can create other revolting smells.

Dr Lai Ka-man, an associate professor at Hong Kong Baptist University led the study[1] which discovered that  'skin squames' ( or dead skin cells)  are a source of food for the bacteria that live in AC units.

Dr Lai said 'For effective long-term odour control, it is important to reduce the amount of skin squames from entering the air-cooling units.   The simplest way is to install an appropriate filter to capture the skin squames in the air.   A filter that can effectively capture particles less than 0.001 centimetres should help improve the odour problem.'

Specialist air conditioning filters are available for air conditioning beauty salons, cooling for hairdressers, and air conditioning with energy efficient heat pump filters are available for offices and even for domestic air conditioning systems.

We also recommend regular servicing of your air conditioning installation as this help to reduce the amount of skin squames in the unit.  In addition, regular maintenance will prolong the efficiency and maximise the performance of your system while helping to avoid costly breakdowns which can occur through lack of planned preventative maintenance (PPM).

London Cool are able to supply installed air conditioning service and maintenance contracts for all major air conditioner manufactures such as Daikin, Fujitsu, Toshiba, Mitsubishi.

To enquire about our service and maintenance agreements, please give us a call 0800 440 444

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[1] Published in the International Journal of Indoor Environment and Health.