Althoughmanyofusmayfeelair-conditionersbringrelieffromhot,humidorpollutedoutsideair,theyposemanypotentialhealthhazards.Muchresearchhaslookedathowthemovementofairinsideaclosedenvironment---suchasanofficebuilding---canspreaddiseaseorexposepeopleinthebuildingtoharmfulchemicals.
OneofthemorewidelypublicizeddangersisthatofLegionnaire’sdisease,whichwasfirstrecognizedinthe1970s.Thiswasfoundtohaveaffectedpeopleinbuildingswithair-conditioningsystemsinwhichwarmairpumpedoutofthesystem’coolingtowerswassomehowsuckedbackintotheairintake(通风口),inmostcasesduetopoordesign.Thewarmair,filledwithbacteria,wascombinedwithcooled,conditionedairandwasthencirculatedaroundvariouspartsofthebuilding.Studiesshowedthatevenpeopleoutsidesuchbuildingswereatriskiftheywalkedpastairexhaustpipes.
Largeair-conditioningsystemsaddwatertotheairtheycirculatebymeansofhumidifiers(湿度调节器).Inoldersystems,thewaterusedforthisprocessiskeptinspecialreservoirs,thebottomsofwhichprovidebreedinggroundsforbacteriawhichcanfindtheirwayintotheventilation(通风)system.Therisktohumanhealthfromthissituationhasbeenhighlightedbythefactthattheimmunesystems(免疫系统)ofapproximatelyhalfofworkersinair-conditionedofficebuildingshavedevelopedtheabilitytofightofftheorganismsfoundatthebottomofsystemreservoirs.Butchemicalscalled“biocides”areaddedtoreservoirstomakethemgerm-free,andtheyaredangerousintheirownrightinsufficientquantities,astheyoftencontaincompoundsstronglylinkedtocancers.
Finally,itshouldbepointedoutthattheartificialclimaticenvironmentcreatedbyair-conditionerscanalsoaffectus.Inanaturalenvironment,whetherindoororoutdoor,therearesmallvariationsintemperatureandhumidity.Indeed,thehumanbodyhaslongbeenaccustomedtothesenormalchanges.Inanair-conditionedlivingorworkingenvironment,however,bodytemperaturesremainwellunder37℃,ournormaltemperature.Thisleadstoaweakenedimmunesystemandthusgreaterexposuretodiseasessuchascoldsandflu.
Choosecorrectanswerstothequestion:
1.WhatdoweknowaboutLegionnaire’sdiseasefromthepassage?
A.Itwasthemostwidelyconcernedofficehazard.
B.Itcanaffectpeoplebothinsideandoutsidethebuilding.
C.Ithappensonlyinair-conditionedofficebuildings.
D.Itdoesnotdevelopinwell-designedbuildings.
2.Intheoldair-conditionedsystems,bacteriafirstdevelop______.
3.Thefactthatabouthalfofworkersdevelopedtheabilitytofightoffthebacteriamay__.
A.relievepeople’sworryaboutthedangercausedbythebacteria
B.helppeoplefindaneffectivewaytogetridofthebacteria
C.reflecttheseriousdangerbroughtbythebacteria
D.causeseriousdiseasesuchascancerstopeople
4.Theauthormostprobablywantsthereaderstotreatbiocideswithanattitudeof_.
5.Thelastparagraphimpliesthatourimmunesystemcanbeweakenedwhen_•
A.weliveinanartificialclimaticenvironment
B.therearevariationsintemperatureandhumidity
C.ourbodytemperaturesoftenremainnothighenough
D.weareoftenexposedtodiseasessuchascoldsandflu
