▁and ▁c rop ▁resid ues ▁for ▁their ▁domestic ▁energy ▁needs . ▁Among ▁those ▁who ▁use ▁ind oor ▁cook ing ▁st ov es , ▁the ▁poor est ▁families ▁living ▁in ▁rural ▁areas ▁most ▁frequently ▁use ▁solid ▁fu els , ▁where ▁it ▁continues ▁to ▁be ▁re lied ▁on ▁by ▁up ▁to ▁ 9 0 % ▁of ▁households . ▁House holds ▁in ▁developing ▁countries ▁consume ▁significantly ▁less ▁energy ▁than ▁those ▁in ▁developed ▁countries ; ▁however , ▁over ▁ 5 0 % ▁of ▁the ▁energy ▁is ▁for ▁cook ing ▁food . ▁The ▁average ▁rural ▁family ▁sp ends ▁ 2 0 % ▁or ▁more ▁of ▁its ▁income ▁purch asing ▁wood ▁or ▁char co al ▁for ▁cook ing . ▁The ▁urban ▁poor ▁also ▁frequently ▁spend ▁a ▁significant ▁portion ▁of ▁their ▁income ▁on ▁the ▁purchase ▁of ▁wood ▁or ▁char co al . ▁De for est ation ▁and ▁er os ion ▁often ▁result ▁from ▁har vest ing ▁wood ▁for ▁cook ing ▁fuel . ▁The ▁main ▁goal ▁of ▁most ▁improved ▁cook ing ▁st ov es ▁is ▁to ▁reduce ▁the ▁pressure ▁placed ▁on ▁local ▁for ests ▁by ▁reducing ▁the ▁amount ▁of ▁wood ▁the ▁st ov es ▁consume , ▁and ▁to ▁reduce ▁the ▁negative ▁health ▁impact s ▁associated ▁with ▁expos ure ▁to ▁to xic ▁smoke ▁from ▁traditional ▁st ov es . ▁ ▁Air ▁poll ution ▁O ften ▁used ▁in ▁open ▁fires ▁or ▁poor ly ▁vent il ated ▁st ov es , ▁solid ▁fuel ▁burning ▁is ▁a ▁significant ▁source ▁of ▁ind oor ▁air ▁poll ution . ▁Sol id ▁fuel ▁smoke ▁contains ▁thousands ▁of ▁subst ances