路透社紐約健康消息最新研究發(fā)現(xiàn)，空氣中的臭氧水平只要輕微增長都會(huì)對(duì)兒童的健康產(chǎn)生不良影響，以致耽誤他們的正常學(xué)習(xí)?？諝馕廴疽呀?jīng)成為學(xué)生因呼吸系統(tǒng)疾病而缺課的最重要原因。

位于地球大氣層上空的天然臭氧可以阻擋太陽紫外線的輻射，對(duì)人體有保護(hù)作用。然而，逗留在地球表面的“人工臭氧”則是一種傷害性的污染物。這種“人工臭氧”由汽車排放出來的廢氣在光照作用下發(fā)生化學(xué)反應(yīng)生成，被吸入人體后會(huì)引起咳嗽、呼吸急促、惡心嘔吐等反應(yīng)，并可造成永久性的肺損害，兒童和老人更容易受到損害。

美國的研究人員對(duì)空氣中3種最常見的污染物：臭氧、二氧化氮和微塵進(jìn)行了分析，并將分析結(jié)果同1996年上半年中2,081名4年級(jí)學(xué)生里每天的缺課率進(jìn)行比較。這些孩子全都居住在洛杉磯附近方圓200英里范圍以內(nèi)。在電話采訪中，研究人員針對(duì)學(xué)生的疾病原因，對(duì)所有的醫(yī)生認(rèn)為可能導(dǎo)致這種疾病的因素進(jìn)行了一一記錄，最終確定了學(xué)生們?nèi)闭n的確切原因。

結(jié)果可以看到，在低于目前允許的空氣臭氧水平標(biāo)準(zhǔn)以下的環(huán)境中生活的學(xué)生的健康正在受到損害?？諝庵谐粞跛絻H僅增加十億分之二十，因呼吸系統(tǒng)疾病而導(dǎo)致的缺課率就相應(yīng)地增長83%，伴有咳嗽咯痰的下呼吸道疾病也相應(yīng)地增長了173%。對(duì)另外兩種污染物，微塵和二氧化氮的觀察中，則沒有類似的發(fā)現(xiàn)。

美國過敏·哮喘·免疫協(xié)會(huì)認(rèn)為，臭氧可以對(duì)任何人造成損害，患有哮喘或支氣管炎、肺氣腫等慢性肺病的人更容易受到侵害。目前臭氧水平最高的幾個(gè)美國城市包括洛杉磯、亞特蘭大、菲尼克斯和休斯頓。美國環(huán)境保護(hù)局建議通過幾人共用一輛汽車、公共交通、鼓勵(lì)步行或騎自行車的方法來減少臭氧產(chǎn)生。

airpollutionlinkedtoschoolabsenteeism

newyork(reutershealth)-evensmallincreasesinthelevelsoftheairpollutantozonemayadverselyimpactthehealthofchildrencausingthemtomissschool,anewreportsuggests.

``weareseeingillhealtheffectsinschoolchildrenatlevelswellbelowthecurrentairqualitystandardforallowablelevelsofozone,‘‘dr.frankgillilandoftheuniversityofsoutherncaliforniainlosangeles,toldreutershealthinaninterview.

ozoneisproducedbyachemicalreactionthatoccurswhensunlighthitsairpollutantsemittedinautomobileexhaust.breathingairwithozonecancausecoughing,respiratoryirritation,nauseaandpermanentdamagetothelungsinpeopleofallages,butchildrenandtheelderlyareespeciallyvulnerable.

theinvestigatorsanalyzeddailylevelsofthreecommonairpollutants--ozone,nitrogendioxideandfineparticles--andcomparedthemwithdailyabsenteeismratesof2,081fourthgradersduringthefirst6monthsof1996.

gilliland‘steamalsotelephonedtheparents‘homeseverytimeachildwasabsentfromschool.

duringthetelephoneinterview,theresearchersdeterminedtheexactreasonfortheabsence.ifthereasonwasduetoillness,theyrecordedalltheinformationpertainingtothesickness,symptomsandoutcomesfromdoctororhospitalvisits.allofthechildreninthestudylivedwithina200-mileradiusoflosangeles.

asthelevelsofozoneincreasedintheairbyaslittleas20partsperbillion,theresearcherssawacorrespondingriseinabsenteeismduetorespiratoryillnessincreaseby83%,explainedgilliland.inaddition,theauthorsdocumentedacorrespondingincreaseof173%inlowerrespiratoryillnesswithwetcough.

``thisindicatesapotentiallymoreserioustypeofillnessinvolvingthelungs,ratherthanjustthenoseorthethroat,‘‘gillilandtoldreutershealth.

``airpollutionhasturnedouttobesurprisinglyimportantfactorcontributingtoabsenteeismduetorespiratoryillness,‘‘headded.

similarfindingsfortheothertwopollutants--fineparticlesandnitrogendioxide--werenotobserved,gillilandandcolleaguesnoteinthejanuaryissueofthejournalepidemiology.

whileozonecanaffectanyone,peoplewithasthmaorchroniclungdiseasessuchasbronchitisandemphysemaareparticularlyvulnerable,accordingtotheamericanacademyofallergy,asthmaandimmunology.

whenproducednaturallyintheupperatmosphere,ozoneactsasprotectionfromthesun‘sultravioletrays.butwhenman-madeozonelingersclosertoearth,itisapollutantthatbecomesharmful.

theusenvironmentalprotectionagencyrecommendscarpooling,usingmasstransit,walkingorbikingtoavoidcontributingtoozonelevels.

uscitieswhereozonelevelsarehighestincludelosangeles,atlanta,phoenixandhouston.