Asthma UK community forum

What type of air is the worst for viruses to transfer in?

I thought that a dry environment - outside was safer for me - in that the viruses are carried in droplets of water in the damp uk winter air.

Though then I read that if you have central heating you should have a bowl of water underneath to put moisture back in to the air. I realise that this is indoors where you have some control over the people you come into contact with. Why is moisture in the air good?

I read in the British Lung Function magazine this morning that the dry cold air as found on the Continent (Seasonal Shopping article) is especially bad for some lung conditions. Then also that the moisture droplets get bigger when the weather is colder and that this can cause more problems.

Apologies to anyone trying to fathom out what I am on about. Basically I just want to avoid going out - when possible - in the worst type of weather for my asthma and especially the type of weather when viruses are more able to survive and get inside my lungs.

3 Replies

Hi sandi,

This is quite a complex one - there are a lot of different factors involved, and there are varying opinions on the answers to these questions.

In general, viruses are transmitted by droplet transmission, to an extent - but the droplets are produced from the ill person's respiratory tract rather than from the environment. With cold viruses, though, transmission from things touched by the affected person is quite important, too - if someone blows their nose and then touches a doorknob, for example, the virus can be transmitted that way. If someone in your house has a cold, encouraging them to always wash their hands after blowing their nose and dispose of their dirty tissues can be helpful.

The viruses are actually less well transmitted, outside - it is too cold, during the winter, for the viruses to survive for long. The reason why colds are more prevalent in the winter is not well understood, but it may be because people spend more time cramped together inside, as it is too cold to go out.

Dry air is definitely a trigger for some people - I find that I can't tolerate the dry heat of a sauna at all, but do a little better with the damp heat of a steam room, for example. Again, the reason for this isn't really understood, but it may be because dry air within the airways triggers moisture to come out of the cells of the airways, which lowers the amount of fluid around the cells, which can trigger cells called mast cells within the lungs to release substances like histamine. This is also one of the suggested mechanisms for exercise-induced asthma, where a lot of fluid is lost from the airways.

Everyone is different in their response to moisture in the air, though - some people find they are better, and some people find a humid environment worse - so it is really a case of personal experimentation to see what suits you best.

Hope this helps

Em H


He Emily - good to hear from you

Thanks for your informative reply I think I will print it off for my daughter and husband to see - the washing hands bit!

Its a bit difficult to take it all in so will read it a few times. Generally I think hot dry air suits me - I certainly feel my lungs saying thank you when we go to the Canaries - I just love seeing all that barren countryside - I just know it will not be damp.

I also like being in the sauna but have read/heard that it isnt good for asthmatics and was never sure why. Your answer helps to explain why - ie that it partly depends on an individuals response to the dryness around the cells - have I got that right?

I'm not so sure about saunas and always feel there must be bugs lurking in all that moisture and never want to stay in there when I occasionally convice myself to try it. I did go into one on holiday in Marbella around 2 weeks ago and came back with this horrible virus - it must have been lurking in the sauna waiting for me - not serious. Though thats how it feels - that bugs are just waiting for an asthmatics pathetic lungs to present themselves as a happy breeding ground!


hi Sandi and EmH, I certainly agree that it varies from person to person and time to time - I am fine in saunas but not in steam rooms, opposite to EmH! Generally warm air suits me (and sadly also the viruses) but if it's too humid then it doesnt. If it's cold, then humid is better and dry worse, for me.

Also I find when the weather changes in any direction in humidity or temperature I struggle for a bit.

So it really depends on your own experience though cold and damp generally BAAAAD for people with iffy lungs.

Hope you have the nice sunshine today, it's lovely here (from the inside looking out that is)




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