▁Ty vek ▁ ▁N uc lear ▁agents ▁possibly ▁through ▁radiation ▁shield ing ▁in ▁the ▁l ining , ▁but ▁more ▁important ly ▁by ▁prevent ing ▁direct ▁contact ▁with ▁or ▁in hal ation ▁of ▁radio active ▁particles ▁or ▁gas ▁ ▁Bi ological ▁agents ▁through ▁fully ▁se aled ▁systems — o ften ▁at ▁over press ure ▁to ▁prevent ▁cont am ination ▁even ▁if ▁the ▁suit ▁is ▁dam aged ▁or ▁using ▁power ed ▁air ▁pur ifying ▁resp ir ators ▁with ▁full ▁h ood s ▁and ▁protect ive ▁su its ▁to ▁prevent ▁expos ure ▁( level ▁C ▁protection ▁level ) ▁ ▁Fire / high ▁temper atures ▁usually ▁by ▁a ▁combination ▁of ▁ins ulating ▁and ▁reflect ive ▁materials ▁which ▁reduce ▁the ▁effects ▁( see ▁also ▁Fire ▁proxim ity ▁suit ) ▁ ▁The ▁ha z mat ▁suit ▁generally ▁includes ▁breath ing ▁air ▁supplies ▁to ▁provide ▁clean , ▁un cont amin ated ▁air ▁for ▁the ▁wear er . ▁In ▁labor atory ▁use , ▁clean ▁air ▁may ▁be ▁supplied ▁through ▁attached ▁h oses . ▁This ▁air ▁is ▁usually ▁p ump ed ▁into ▁the ▁suit ▁at ▁positive ▁pressure ▁with ▁respect ▁to ▁the ▁surr ound ings ▁as ▁an ▁additional ▁protect ive ▁measure ▁against ▁the ▁introduction ▁of ▁dangerous ▁agents ▁into ▁a ▁potentially ▁ru pt ured ▁or ▁le aking ▁suit . ▁ ▁Working ▁in ▁a ▁ha z mat ▁suit ▁is ▁very ▁str enu ous , ▁as ▁the ▁su its ▁tend ▁to ▁be ▁less ▁flexible ▁than ▁conventional ▁work ▁gar ments . ▁ ▁With ▁the ▁exception ▁of ▁labor atory ▁versions , ▁ha z mat ▁su its ▁can ▁be