Air horn in cold weather?

I have one of those $25 air horns - this kind of thing:

http://www.nycewheels.com/air-zound-horn.html

It is very useful for commuting, capable of easily penetrating the
headphones of joggers and such. However, I never used it in winter
before because it was too much to take off the bike when parking
outside at the office. Various lights, batteries, etc.

Now I will be able to bring the new bike into the building. So, while
I could continue to use it, I'm concerned about the effect of cold on
the bottle and its contents (air). Surely it not last as long, but
will the bottle get brittle and explode? I think it is best to not
find out the hard way.