The Rad Towns are the irradiated post nuclear remnants of civilization. Easily detectable by the clear difference in the structure, nearby roads, telephone or electric poles, and the tell tale clicking of your Geiger Counter.
Found within Rad Towns are quickly respawning Barrels and Loot Crates. The same chances of getting gear from an airdrop go with the barrels and military crates of a rad town. There are wooden crates which are more likely to drop clothing and other items. The chances of finding higher quality loot are better with the wooden crates than farming barrels. However even better than wooden crates or barrels are military crates: Rectangular, lower to the ground and a darker metallic tint than barrels, the military crates drop more weapon and tool oriented loot.
The effects of radiation in Rust are varying. Radiation is one of the deadliest killers in Rust. It is more lethal the farther into a Rad Town you get. Low doses aren't dangerous on their own and will slightly drain you of health but very high amounts, easily acquirable in the center of a Rad Town, will kill you. Radiation, however, can be negated. Wearing a Hazmat Suit allows one to safely enter a Rad Town. Anti-Radiation Pills can also increase chances of survival. Also, a ridiculous amount of healing items, (i.e. Bandages, Medical Syringes, Large Medkits, Food items, etc) can prevent a quick and untimely death.