A dystopian/utopian fantasy of rebirth and the flowering of the human race.
The warning signs were ignored until at least fifty years after the accident. All attempts to filter and purify the atmosphere failed. The only course of action left was to enjoy the last days under the clear blue sky as the poison took hold. 
As contrails gradually erased the sky, the beleagured human bodies began to revolt. Sinus drains, anti-radiation goggles, lung filters; all fitted as standard to the diminishing numbers of weak babies. 
The last futile barrier fell and the sky bled. Gas mines were installed in the lower atmosphere, but the air was now dead. Protective suits became organic, daily life became a war against the elements, and for the first time in five centuries, a virulent new strain of plague appeared. 
Within two years the atmosphere evaporated. All skin died, and the cross-breeding of metal and plant materials saved the Human Race with a cocoon of chlorophyll sacs. Vastly increased solar radiation destroyed the reproductive capacity of the body, but equally lead to exterior wombs in protective pods. Speech was reduced to sign language, insects flourished and the body became hermaphrodite in only a single generation. 
The body nourished itself with its own exterior fruit, blossoming on thickened skin. The Race diversified – during the birth period, the parent lay dormant as the emerging young were tended to by more hardy individuals, who themselves flowered only once a decade. Photosynthesis fed the body, excess soil was eaten to provide minerals and nostrils closed up completely. Oxygen slowly returned to the world. 
The new children were beautiful. The pineal gland blossomed fully from their foreheads. The skies became blue, insects returned to the non-sentient plants, and the now completely silent vocal chords produced laughing shouts of pollen. The world was clean.