[ricbritain (OP)]

I both live and work in hot countries where the use of air conditioning is prevalent. In my work place of North Africa the local people have concerns over the health implications of using the AC. Even when the ambient temperature may be 40’C they are often reluctant to turn on the air conditioning, especially in cars. Even in a hot gym they prefer to keep the AC off. The issue seems to be that changing from a hot environment to a cold environment is very much detrimental to ones health, especially to the heart. I am skeptical of this, especially since the people I am talking about are generally under 30 years old. However since I am not from a country that relies on the use of air conditioning and they are I do wonder if they are in any way right in their concerns.

As well as this I also hear from all nationality’s the assertion that their AC use has led to a list of minor ailments, including stiff back and neck, headaches and common cold symptoms. Once again I am skeptical of these claims.

I would be very interested in any information on the subject of health concerns over air conditioning. I think this affects many people across the board and it particularly relevant at this time of year with the sun beating down on many of us.

[graham.d]

It has been found that large commercial Aircon systems can harbour Legionaires Disease and, recently, it has been found that there is also a correlation between the disease and vehicle aircon systems. However I don't think the incidence is very high and, in my opinion, it is better for concentration when driving to be at 22C rather than 30C+.

It may be viewed that Aircon is not natural and therefore may have unwanted effects on the human body, but generally countries that use a lot of aircon (USA for example) have higher health standards that most places so any problems from aircon can't be that significant. Personally, I like to remain at a reasonable temperature when working though I think there is a tendency to overcool sometimes.

[Variola]

Simple use of screen wash in car windscreen washer bottles is enough to kill anything lurking in there. AC isn't the problem it was the water.
Same applies with commercial AC systems, correct and regular cleaning and maintenance of the system prevents Legionnaire's from infiltrating the system . 
In regards from going hot to cold being bad, if you were going straight from 35^c to 2^c then it may be a shocl tot he system. But to drop just 5^clower,won't make a jot of difference to your body. In fact I would suggest people are more at risk from overheating and heat stroke than they are from AC.

[tommya300]

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Relating this comment to the subject of Air Conditioning...
Tension, tension headaches, stiffness, etc.... are all physical reactions related to the feeling of being cold. Even a sniffle from a runny nose is physical reaction of a nasal membrane spasum.

The difference in temperatures can be, let's say the body is used to 90 deg F, the change to 60 deg F, this may be perceived as being cold.
 If the body is used to 30 degrees F, 60 deg F may feel hot.

Going from hot to cold the body reacts, (muscles), a direct cool draft on the neck let's say, tention occurs. If this muscle tention spasums, or cramps, sometimes this cramp does not relax, an involuntary reaction occurs and the body reacts to this through its pain receptors. The next thing you may hear my neck hurts and it is stiff! Is this a symptom of a cold or flu or a muscle spasum from tention?

This part is a physical reaction that can reverse in time with constant exposure.
Acclimation is the key word. Training the body to accept change, takes time if the subject is willing.

The Bio part coincides with filter maintenance, seeing if there is any stagnet water that will be a breeding ground for bacteria. Checking systems that use air ducts monitoring the air flow quality and adjusting as needed.

Temperature change relatively depends on what the body is accustom to begin with. An Eskimo may think winter in Southern Canada is a scorcher. 40 deg F  in New England may seem warmer than 40 deg F in Florida.
The only thing here is perception of change and the reaction to it.
You can equate Good and Bad to what type of pre-maintenance is being applied.

Can we depend on paranoia, trust no one, depend on nothing?
Does the uncertainty of the unseen unknown rules?
Suggestion to the troups, "let's get frosty?"
Howard Hughes syndrome attacks again?
A million at boys are erased by a single blunder?
.

[ricbritain (OP)]

I wasn't thinking so much of Legionaries disease. I think that most here agree that the change in temp will not result in an significantly adverse health conditions. As mentioned, I think there is a degree of paranoia towards what may be perceived as modern devices. I wish that I could fine something concrete to back up my frowned upon opinion that air conditioners do not cause all these ailments.