Know you radiation Particles

Know the types of radiation particles. Before we continue, we should mention the three different types:

Alpha particles. These are the weakest and, during an attack, are virtually non-existent as a threat. Alpha particles will survive for only a couple inches in the air before they are absorbed by the atmosphere. They possess a minuscule threat from the exterior, however, they will be fatal if ingested or inhaled. Standard clothing will help protect you from Alpha particles.
Beta particles: These are faster than Alpha particles and can penetrate further. They will travel for up to 10 meters (10 yards) before they are absorbed into the atmosphere. Exposure to beta particles is not fatal unless exposed for prolonged periods; which may cause "Beta burns," almost like painful sunburn. They pose a serious threat, however, to the eyes, should they be exposed for a prolonged period. Once again this is harmful if ingested or inhaled, and clothing will help prevent Beta burns.
Gamma Rays. Gamma Rays are the deadliest. They can travel for nearly a mile in the air and penetrate just about any kind of shielding. Therefore gamma radiation will cause severe damage to the internal organs even as an external source. Sufficient shielding will be required.

A shelter's PF against radiation will tell you how many times less a person inside the shelter will receive radiation compared to open space. For example, RPF 300 means that you will receive 300 times less radiation in the shelter than in the open.
Avoid exposure to Gamma radiation. Try not to spend more than 5 minutes exposed. If you are in a rural area, try finding a cave, or a fallen log into which you can crawl. Otherwise just dig a trench to lie in, with stacked earth around you.