▁These ▁include ▁waiting ▁until ▁one ▁reaches ▁a ▁specific ▁repet itive ▁group , ▁and ▁simple ▁surface ▁intervals ▁based ▁on ▁the ▁recent ▁div ing ▁history . ▁He avy ▁exercise ▁following ▁div ing : ▁The ▁risk ▁is ▁thought ▁to ▁be ▁associated ▁with ▁an ▁increased ▁pul mon ary ▁sh unt ▁that ▁allows ▁ven ous ▁blood ▁and ▁b ub bles ▁to ▁by pass ▁the ▁l ungs , ▁allowing ▁b ub bles ▁into ▁the ▁ar ter ial ▁system . ▁Cons umption ▁of ▁alco hol ▁before ▁and ▁after ▁div ing : ▁Al co hol ▁can ▁increase ▁de h yd r ation ▁and ▁heat ▁loss , ▁both ▁considered ▁risk ▁factors ▁for ▁decom pression ▁sick ness . ▁Use ▁of ▁some ▁dru gs : ▁Bre ath hold ▁div ing ▁after ▁sc uba ▁or ▁surface ▁supplied ▁div ing : ▁B ubble ▁formation ▁is ▁more ▁likely ▁after ▁significant ▁decom pression ▁stress , ▁and ▁the ▁risk ▁increases ▁with ▁resid ual ▁in ert ▁gas ▁load , ▁so ▁deeper ▁fre ed iving ▁and ▁more ▁inten se ▁exercise ▁will ▁have ▁a ▁greater ▁associated ▁risk . ▁D iving ▁after ▁long ▁fl ights : ▁Long ▁distance ▁flying ▁tends ▁to ▁leave ▁the ▁trav eller ▁tired ▁and ▁somewhat ▁de h yd r ated , ▁which ▁is ▁thought ▁to ▁be ▁a ▁factor ▁pre dis pos ing ▁to ▁D CS ▁due ▁to ▁less ▁efficient ▁in ert ▁gas ▁elim ination . ▁Statistics ▁are ▁ins u fficient ▁to ▁show ▁cause ▁and ▁effect ▁but ▁about ▁a ▁third ▁of ▁decom pression ▁sick ness ▁inc idents ▁reported ▁ann ually ▁from ▁the ▁Car ib bean ▁occur ▁after ▁the ▁first ▁day '