▁were ▁switched ▁off , ▁or ▁dim med ▁and ▁shield ed ▁to ▁def lect ▁light ▁down ward . ▁Ess ential ▁lights ▁such ▁as ▁traffic ▁lights ▁and ▁vehicle ▁head light s ▁were ▁fitted ▁with ▁sl otted ▁covers ▁to ▁def lect ▁their ▁be ams ▁down wards ▁to ▁the ▁ground . ▁ ▁Sh ops ▁and ▁fact ories ▁had ▁particular ▁problems . ▁Fact ories ▁with ▁large ▁areas ▁of ▁glass ▁roof ing ▁found ▁it ▁impossible ▁to ▁install ▁temporary ▁black out ▁pan els ▁and ▁permanent ▁methods ▁( such ▁as ▁paint ) ▁lost ▁natural ▁light ▁during ▁day light . ▁Sh ops ▁had ▁to ▁install ▁ ▁double ▁" air lock " ▁doors ▁to ▁avoid ▁lights ▁showing ▁as ▁customers ▁arrived ▁and ▁depart ed . ▁ ▁Black outs ▁proved ▁one ▁of ▁the ▁more ▁un ple asant ▁aspects ▁of ▁the ▁war , ▁dis rupt ing ▁many ▁civil ian ▁activities ▁and ▁causing ▁w ides p read ▁gr umb ling ▁and ▁lower ▁mor ale . ▁ ▁The ▁black out ▁was ▁enfor ced ▁by ▁civil ian ▁AR P ▁w ard ens ▁who ▁would ▁ensure ▁that ▁no ▁buildings ▁allowed ▁the ▁slight est ▁pe ek ▁or ▁g low ▁of ▁light . ▁Off enders ▁were ▁li able ▁to ▁string ent ▁legal ▁pen alt ies . ▁ ▁Black out ▁restrictions ▁greatly ▁increased ▁the ▁d angers ▁of ▁night ▁driving ▁and ▁fatal ities ▁increased ▁as ▁a ▁consequence . ▁As ▁a ▁result , ▁some ▁aspects ▁were ▁relax ed ▁and ▁speed ▁limits ▁were ▁lower ed . ▁Un sur pr ising ly , ▁fatal ities ▁were ▁also ▁recorded ▁amongst ▁merchant ▁se aman ▁falling ▁into ▁the ▁do cks