to do with the water - hair dresser told me that the water here is very harsh on the hair. The chemicals that they put in it to treat it will bond themselves to the root of your hair, causing hair to fall out and potentially baldness (because the nerve/root has died).

I have to say, personally, I notice alot of hair falling out in the shower, yet when I am at home for any length of time, this hair loss slows down/stops, so it would seem this is most probably the case.