Potassium iodide is the active ingredient in "fallout pills," pills that prevent the accumulation of radioactive iodines in the thyroid, which can cause thyroid cancer. Potassium iodide pills or potassium iodide powder should be consumed in regular doses if one might be exposed to radiation, such as during a nuclear war. The recommended oral dosage is 16 mg for infants under one month old, 32 mg for infants 1-36 months old, 65 mg for children 3-12, and 130 mg for adults. In the US, whether to stockpile potassium iodide for possible use during a nuclear war or Trans-Pacific fallout from an overseas war is a decision made at the state level by governors. Outside of the US, stockpiles vary by country.
Potassium iodide tastes bad and is a mild irritant. It should be handled with gloves to prevent skin irritation. To make it more palatable, mix it in with sugar water or just water. It is important to realize that potassium iodide does not protect someone from being damaged by radiation, only lowers the chance that trace amounts of inhaled or ingested radioactive iodines (as released in ground-level nuclear explosions or nuclear accidents) will accumulate in the thyroid gland and cause cancer. Because the thyroid can only hold a limited amount of iodide, the potassium iodide salt keeps the thyroid occupied, preventing it from concentrating any radioactive iodines that are swallowed. The type of iodine used to cleanse wounds, molecular iodine, is poisonous, offers no protection benefits, and should never be consumed.
The ability of potassium iodide to prevent thyroid cancer during radiological emergencies was proven following the Chernobyl nuclear reactor disaster in April, 1986, when 10.5 million children and 7 million adults in Poland were given a saturated potassium iodide solution as a prophylactic measure against accumulation of radioactive iodines in the thyroid. The US FDA approved the use of potassium iodide as protection against thyroid cancer in 1982.
There are other steps one should take to avoid radiation poisoning while in a high protection factor fallout shelter. Besides making sure the roof is covered in at least 3 feet of earth, be sure to filter all water through a two-ended can or barrel containing two feet of earth dug from more than four inches below the ground. Filtering air is not a high priority, as the most dangerous fallout particles are heavy, the size of small pebbles, and will not float into a shelter. Tiny aerosolized fallout particles pose minimal danger. A more useful application for filters would be to exclude flies, mosquitoes, and other pests from a shelter. Filters should not block too much of the air flow, as ventilation (including a large exhaust hole) is likely to be a major priority in any crowded or small fallout shelter.
