Regarding common cold and indoor athmosphere
At least in the northern countries also the quality of indoor atmosphere changes 
during winter season. Due to continuous central heating the indoor air is very 
dry which has negative effect on the condition of nasal mucosa and  may impair
mucosal defence mechanism.

Markus Rautiainen  

Anders Cervin:
>Regarding common cold
>In Sweden common colds are a major problem in our daycare centers. However 
>the last couple of years have seen a development of outdoor daycare 
>centers, which spend most of their daily activities regardless the weather, 
>outdoors. This has resulted in a drastic decrease in upper respiratory 
>tract infections in this centers and possibly supporting the indoor, 
>crowding theory
>
>sincerely
>
>Anders Cervin
>-----Ursprungligt meddelande-----
>Från:  Ron Eccles ÄSMTP:[log in to unmask]Å
>Skickat:       den 14 oktober 1998 11:08
>Till:  [log in to unmask]
>Ämne:  Re: Cold and common colds
>
>In response to the question about chilling and colds by  Ron Halweil- all 
>the experiments have not
>been able to show any increased susceptibility to infection or any increase 
>in symptom severity-
>however just because this relationship has not bee shown in the lab does 
>not mean it does not occur
>in the field !!!
>
>Some of the original experiments were reported by-
>
>Douglas R G J, Lindgren K M, Couch R B (1968) Exposure to cold environment 
>and rhinovirus common
>cold. Failiure to demonstrate effect. New England Medical Journal 279: 
>742-747.
>
>Dowling H F, Jackson G G, I.G. S, Inouye T (1958) Transmission of the 
>common cold to volunters
>under controlled conditions. II. The effect of chilling of the subject upon 
>susceptibility. American
>Journal of Hygiene 66: 59-65.
>
>Andrewes C H (1950) Adventures among viruses. III. The puzzle of the common 
>cold. New England
>Medical Journal 242: 235-240.
>
>Some of my own ideas about cold and colds are given below-
>
>
>Common colds are much more common during the cold, wet, dark days of winter 
>and this
>seasonality has been explained by some effect of the weather on the common 
>cold viruses and how
>they are spread.
> It is generally believed that the viruses spread more easily during winter 
>because we tend to
>spend more time indoors in poorly ventilated rooms.  Another factor could 
>be that sunlight kills
>viruses and that there is far less sunlight  during  the short dark days of 
>winter.  However, in
>recent  years these explanations of the seasonality of common colds have 
>been modified as
>scientists have realised that changes in the weather affect mankind as well 
>as the common cold
>viruses.  Another explanation for the increased incidence  of common colds 
>during winter may be
>that due to changes in our immune system we are more susceptible to 
>infection.  The cold wet
>weather and lack of sunlight certainly makes many of us feel 'under  the 
>weather' or depressed and
>these psychological changes can affect our immune system.
>Scientists have known for some time that our mood influences our immune 
>system and that when
>we are stressed or depressed our susceptibility  to infection is increased. 
> Perhaps the seasonal
>nature of common colds  is due to the effects of weather on our bodies 
>rather  than influences on
>the spread of viruses. If this was the case then one way of avoiding colds 
>would be to migrate
>South with the Swallows at the end of the summer and enjoy the summers in 
>both the Northern and
>Southern halves of the world. This would be a rather expensive but 
>certainly very enjoyable way of
>avoiding common colds.
>
>Best wishes
>
>Ron Eccles
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>Professor Ronald Eccles
>Director, Common Cold Centre
>Cardiff University
>Cardiff CF1 3US
>Wales, United Kingdom
>
>voice 44-1222-874099
>fax     44-1222-874093
>WEB URL  http://www.cf.ac.uk/uwcc/biosi/associates/cold/home.html
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
>
>


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