30. fn addition to tn:. T1:,r-* radiation of gama rays and neutrons, a large amount of radioactive elements wirf also be pioauced by fission processes and possibly other neutron reactions i" i;;-";;;;s material. These elements w1fl adhere to particJ-es formed from "u.po" autii" and, in the case of a land surface burst' also from ground nateriaf. ir.e r.aio."tivity associatea viin Jucrr larti.cles rs called residual radiaticn. for' " a"to"uiiln ut o" close to the surface, initia-uy released neutrons vilr- induce xadioactivity in the ground adding to the fission and weapon debris, r""ia"ui "rai;il;-;" some ground materiar wilf be drar"m into the firebau' since a r""r." ""r"tton will not produce any radioactive rest products. its contribution to res idu"i -""ii"tior. vi,' ie "^"".a--l"rv ry neutron-.induced activity. 3f' Radioactive elements will 10se their radioactivity lrith tine due tc ,,decay,?,The rate of decay varies fron a fraction or-u.-"u"ooa to many years, depending an the element considered. Tbo important uf.r.rrt", st'cntium 90 and cesiurn f3Z, for instance, wifl retain ha.lf of tfr"ir ,*aioi"iivity .ft"" about 30 years, and hence cause fong-tenn health h?-zard.:. carbon f\, -wfricir is formed fron it "-.ritrog"r, r,. the atmosphere wherr irradiated with "",rtio.r" "- rr*= a half-life of about 5,Boo years and 'rill thus continue to give "rdl ";;i;;iin'oo " "* to many generations. 32' Particles containing residual rad.iation are usuarly refe*ed to as I.al1out. The .later the fallout reaches the ground" the iess hazardous it is, due to the decay of the radioactivity' Earry falloit """"ri=i"rv for a su.r'face or very low air illll: r"t hence these types r'rill n""" r.r'ro". serious consequences than an air