how to pronounce WHO?

[light]

hello,
how is WHO, the abbrev. of world health organization, pronounced?
as one word (like the question word) or letter by letter?

is there a set rule for the pronunciation of abbreviations?

[seval]

hello,
how is WHO, the abbrev. of world health organization, pronounced?
as one word (like the question word) or letter by letter?
is there a set rule for the pronunciation of abbreviations?

Hello,
I think (in fact this is the thing I was taught) abbrev. are pronounced letter by letter.To me it would be incomprehensible if they were pronounced as one word.

[rogusx]

Well, there are exceptions to that; some acronyms are usually pronunced as one word (UNICEF comes to mind).

[light]

Thank you for your answers. There was a mistake in my question. WHO is not an abbreviation but an acronym. Anyway, I heard WHO pronounced letter by letter on CNN.

Rogusx you are right, some acronyms such as NATO, are pronounced as one word. So the question is how are we going to know when to pronoounce as one word or letter by letter.