Akira Kurosawa's Dreams (1990) contains a short called "Mt. Fuji in Red", which depicts large poisonous gaseous clouds of radiation taking over Japan.
The film's second nightmare sequence. A large nuclear power plant near Mount Fuji has begun to melt down, painting the sky a horrendous red and sending the millions of Japanese citizens desperately fleeing into the ocean. Three adults and two children are left behind on land, but they soon realize that the radiation will kill them anyway.
:: Akira Kurosawa's : Dreams : Mount Fuji in Red : SCRIPT ::
I: What is it? What's happening? Has Fuji erupted? How terrible!
Woman with baby: It's worse than that! Didn't you know? The nuclear power plant has exploded.
Nuclear engineer: The six atomic reactors. They are exploding one after another. Japan is so small there's no escape!
Woman with baby: We all know that. No way out. But we still have to try. No other way.
Woman with baby: This is the end.
I: But... ...what happened? Where did all those people go? Where did they escape to?
Nuclear engineer: To the bottom of the sea. The dolphins. Even they are leaving.
Woman with baby: Lucky dolphins. They can swim away.
Nuclear engineer: It won't help. The radioactivity will get them.
The clouds... ...the red one. It's Plutonium 239. 10,000,000th of a gram causes cancer.
The yellow one is strontium 90. It gets inside you... ...and causes leukemia.
The purple one is Cesium 137. It affects reproduction. It causes mutations.
It makes monstrosities.
Man's stupidity is unbelievable. Radioactivity was invisible. And because of its danger, they colored it. But that only lets you know which kind kills you.
Death's calling card. See you later.
I: Wait! Radiation doesn't kill you at once.
Nuclear engineer: So What? A slow death is even worse. I refuse to die slowly.
Woman with baby: Adults dying -- they've lived long enough already. But the children haven't even lived yet. It's unfair!
Nuclear engineer: Waiting to die isn't living.
Woman with baby: They told us that nuclear plants were safe. Human accident is the danger, not the nuclear plant itself. No accidents, no danger. That's what they told us. What liars! If they're not hanged for this, I'll kill them myself.
Nuclear engineer: Don't worry. The radioactivity will do that for you. I'm sorry. I am one of those who deserve to die.
( Nuclear Engineer leaps to his death. )