Theconcentrationofpeople,economicactivityandenergydemandintheworld’s
growingcitiesmeansthatpoorairqualityisoftenregardedasanurbanproblem.Yetpoorair
qualityalsoaffectsmanyruralcommunities,particularlywherehouseholds
continuetorelyonsolidbiomassforcookingandkeroseneforlighting.Moreover,themajor
pollutants–includingsecondary pollutantsformedbychemicalreactionsinthe
atmosphere–canbetransportedlargedistancesfromtheirsources.