Our Living conditions....Thank You all....

A big thank you to all my readers for having been so supportive with your comemnts. Though I would love to reply to each of you individually, it somehow doesnt seem possible with the amount of time on my hands:( Here is an article for your general information and which everyone should be aware of. This point for discussion was raised by one of you fine folks (Sans) and I am glad to reply. The question is:

Can living in an Airconditioned home 24 hrs (or 14/15 hrs) a day, "cause" or "agravate" cough, cold , fever, flu or any other respiratory disease?

Before I answer it in a simple 'Yes' or 'No' manner, let me give you a basic insight into what affects our living conditions in a room.

Human occupancy and activity vitiate air in occupied rooms and give a sense of discomfort to the occupants. The changes in air that take place in confinded places are both chemical and and physical.

A) Chemical Changes:
The air becomes progressively contaminated by carbon dioxide and the oxygen content decreases due to metabolic processes. An average person at rest gives off 0.7 c.ft of carbon dioxide per hour and this may increase up to 2 c. ft. during physical activity.

B) Physical Changes:
By far the important changes that occur due to human occupancy are the physcial changes. These are:

1) Rise in temperature:
The indoor temperature tends to rise as a result of the emanation of body heat. A man at rest gives off approximately 400 Btu per hour. One Btu (British Thermal Unit) is the quantity of heat required to raise the temperature of 1 pound of water to 1 deg F. Under conditions of physical exertion, the heat output may go upto 4000 Btu.

2) Increase in humidity:
There is an increase in the relative humidity due to moisture evaporated from the skin and lungs. The expired air contains about 6 percent of water vapour.

3) Decrease in air movement:
In crowded places, the natural movement of air is impeded.

4) Body odours:
Unpleasant odours arise from foul breath, perspiration, bad oral hygiene, dirty clothese and 'other' sources.

5) Bacterial pollution:
The exhaled air contains micro-organisms in suspension. These are principally saprophytic bacteria and may include pathogenic bacteria. These organisms are discharged into the air during coversation, coughing, sneezing and talking loudly.

Unless the vitiated air is replaced by fresh air, it may adversely affect the comfort, health and efficiency of the occupants. It is known that a feeling of suffocation or discomfort is experienced by the occupants in insufficiently ventilated rooms and also complaints of headache, drowsiness, leathargy and inability to concentrate. There is also the risk of droplet infection and lowered resistance to disease on prolonged exposure.

I guess you would have got a basic idea into the vitals of the air in an occupied room. Now lets analyse how an air conditioner can affect these.

Comfort zones may be defined as the range of temperatures over which the majority of adults feel comfortable, There is no unanimous decision on a singe zone for all people because comfort is a quite a complex subjective experience which depends not only on physical, physiological factors but also on psychological factors which are hard to determine.

Considering only the environmental factors: Comfortable thermal conditions are those under which a person can maintain normal balance between production and loss of heat, at normal body temperature without sweating.

In India zones evaluated are as below:

Pleasant and cool 69F
Comfortable and cool 69-76F
Comfortable 77-80F
Hot and uncomfortable 81-82F
Extremely hot 83+ F
Intolerably hot 86+F

Please note that these are corrected effective temperature and not the actual temperature recorded.

Considering ventilation, a person needs atleast 1000 to 2000 cu ft of fresh air per person per hour in order to remove the carbon dioxide and other noxious gases expired by him and others around him. He also needs about 50 to 100 sq ft of floor space to achieve the same.

A room should have the following ventilation means:
a) Natural ventilation, by means of doors and windows and preferably they should face each other providing 'cross ventilation'.

b) Exhaust ventilation, where air is extracted or exhausted to the outside by fans.

c) Plenum ventialtion where fresh air is blown into the room by centrifugal fans so as to create a positive pressure and displace the vitiated air. This type of ventilation is usually used for supplying air to air conditioned buildings where air is supplied through ducts at desired points. Usually most ducts do not supply air or they arent cleaned well which leads to infection.

d) Balanced ventilation which is a combo of both exhaust and plenum ventilation systems.

e) Air Conditioning: Ok, now we come to the most important part here...finally, atlast;))))

By definition, air conditioning is: the simultaneous control of those factors that affect botht he physical and chemical conditions of the atmosphere within any structure. These factors include: temperature, humidity, air movement, distribution, dust, bacteria, odours and toxic gases. most of which affect human health and comfort.

Actually with very good use of air conditioning it is possible to maintain a germ free atmosphere as they do in operating theatres. Frequent disinfection of the air conditioned area is a must. In general the temperature difference between the outside air and the air conditioned air should not be more than 10-15 deg F and the presence of 'transition rooms' is also necessary so that people may not be suddenly exposed to high or low temperatures.

The next time you step into your office, please haul up your HR guy or house keeper and ask him if your work area has all these required ventilation systems to prevent infection;))))

Does having the AC continously ON has any negative impact on a person's cough and cold or fever? will it increase it??"

As you will have understood, the ac is meant for our comfort and used properly it will not aggravate cough or fever. But there is a possibility that some people might have the chills if they are exposed to continuous chill air (like sitting right under the ac duct or so).

Actually most offices in Chennai are over cooled rather than being comfortable. The ac ducts arent cleaned, the area isnt disinfected, and there is nil ventilation. God help the executives who spend about 12 to 14 hours slogging it out inside :(

Thank you once again folks and please do visit this place regularly and leave behind a line or two as comments or mail me to let me know your opinions. You really do not know how much it means for me to read your comments!