Airpollutioncanaffectourhealthinmanywayswithbothshort-termandlong-termeffects.Differentgroupsofindividualsareaffectedbyairpollutionindifferentways.Someindividualsaremuchmoresensitivetopollutantsthanareothers.Youngchildrenandelderlypeopleoftensuffermorefromtheeffectsofairpollution.Peoplewithhealthproblemssuchasasthma,heartandlungdiseasemayalsosuffermorewhentheairispolluted.Theextenttowhichanindividualisharmedbyairpollutionusuallydependsonthetotalexposuretothedamagingchemicals,i.e.,thedurationofexposureandtheconcentrationofthechemicalsmustbetakenintoaccount. 　　Examplesofshort-termeffectsincludeirritationtotheeyes,noseandthroat,andupperrespiratoryinfectionssuchasbronchitisandpneumonia.Othersymptomscanincludeheadaches,nausea,andallergicreactions.Short-termairpollutioncanaggravatethemedicalconditionsofindividualswithasthmaandemphysema.Inthegreat"SmogDisaster"inLondonin1952,fourthousandpeoplediedinafewdaysduetothehighconcentrationsofpollution. 　　Long-termhealtheffectscanincludechronicrespiratorydisease,lungcancer,heartdisease,andevendamagetothebrain,nerves,liver,orkidneys.Continualexposuretoairpollutionaffectsthelungsofgrowingchildrenandmayaggravateorcomplicatemedicalconditionsintheelderly.ItisestimatedthathalfamillionpeopledieprematurelyeveryyearintheUnitedStatesasaresultofsmokingcigarettes. 　　Researchintothehealtheffectsofairpollutionisongoing.Medicalconditionsarisingfromairpollutioncanbeveryexpensive.Healthcarecosts,lostproductivityintheworkplace,andhumanwelfareimpactscostbillionsofdollarseachyear.