Nuclear, biological, chemical (NBC) weapons disperse biological, chemical, or radioactive agents to inflict injury or cause contamination or damage.
A dirty bomb using a conventional explosion to disperse radioactive contaminants would be included under the first category, as would a nuclear device that relies on nuclear fission to generate an explosion. Examples of biological agents would include anthrax and smallpox. Examples of chemical agents would include mustard gas, ricin, VX, and sarin gas. Due to the truly catastrophic exposure they pose, insurers generally exclude coverage for NBC perils—or seek a substantially higher premium to cover them—even when covering other acts of terrorism.