Toomanycarshavecreatedalotofseriousproblemsinourworld.Besidescongestion,accidentsandfastfuelconsumption,carsareresponsibleforagoodpartofairpollutioninbigcities.Allthetime,theyarepumpinghugeamountsofwastegasesintotheatmosphere.Thesegasesareveryharmful,causingdiseaseandevendeath.Lastwinter,carfumesformedheavysmogoverBeijing,makingtheskygloomyforweeksanddeterioratingpeople'shealth.
Onepossiblesolutionistodesignanddevelopcleancarsandcleanfuels.InTsinghuaUniversity,campusbusesaredrivenbyelectricity.InBeijingsomeofthepublicbusesbegintorunonnaturalgas,whichdoesnotgiveoffasmuchcarbondioxideasthepetrol.Butitmaytakedecadesforthenewmodelsofcleancarstocompletelyreplacethetraditionalones.
Anothersolutionistodevelopmodernpublictransportationsystemsandrestricttheuseofprivatecars.Ifthepriceofpetrolrisesconstantlyandthepublicvehiclesareefficientandconvenientenough,mostpeoplewillnotprivatecars.Andthetotalnumberofcarsinbigcitieswillreducegreatly.Onthewhole,theeliminationofairpollutionneedstheco-effortsfromthegovernment,thepublicandtheenvironments.Thisproblemwillbesolvedonlywiththehelpofscienceandtechnology.