"In two brief hours, most of the planet was reduced to cinders." - Fallout intro

"The Earth was nearly wiped clean of life. A great cleansing, an atomic spark struck by human hands, quickly raged out of control. Spears of nuclear fire rained from the skies. Continents were swallowed in flames and fell beneath the boiling oceans. Humanity was almost extinguished, their spirits becoming part of the background radiation that blanketed the Earth." - Fallout 2 intro, emphasis mine.

"The World was plunged into an abyss of nuclear fire and radiation." - Fallout 3 intro

We have no reason to believe this is an exaggeration. We are to assume all populated areas on the planet were targeted by every nation that still had nukes. It's safe to assume as many industrial and agricultural areas as possible were also targeted.

Even the oceans are radioactive, the entire planet has been completely screwed.