Even so, each letter returned to Mr. Skaar was a reminder that the wheels of justice can grind so agonizingly slowly that by the time they churn out a resolution, many who needed relief are gone.

The Palomares disaster occurred on Jan. 17, 1966, when an American B-52 bomber on a Cold War patrol exploded during a midair refueling accident, sending four hydrogen bombs hurtling toward the ground. They were not armed, so there was no nuclear detonation, but the conventional explosives in two of the bombs blew up on impact, scattering pulverized plutonium over a patchwork of farm fields and stucco houses.

Plutonium is extremely toxic, but it often acts slowly. The alpha-particle radiation it gives off travels only a few inches and would not penetrate skin. But inhaled plutonium dust can lodge in the lungs and steadily irradiate surrounding tissue, gradually inflicting damage that can cause cancer and other ailments, sometimes decades later. A single microgram absorbed in the body is enough to be harmful; according to declassified Atomic Energy Commission reports, the bombs that blew apart at Palomares contained more than 3 billion micrograms.

The Air Force sought to clean up the disaster quickly but quietly. It threw together a response crew made up of low-ranking airmen with no special training — cooks, grocery clerks, even musicians from an Air Force band — and rushed them to the scene. Wearing nothing more protective than cotton coveralls and sometimes a paper dust mask, they cut down contaminated crops, scooped up contaminated soil, and packed the material in 5,300 steel barrels that were shipped back to the United States to be buried in a secure nuclear waste storage site in South Carolina.