However , if the health - related air quality objectives are to be met , light duty diesel vehicles such as taxis , and public light buses , will have to switch to cleaner fuels such as liquefied petroleum gas ( lpg ) 不過,要達(dá)至符合健康的空氣質(zhì)素指標(biāo),輕型柴油車輛如的士和公共小型巴士,必須改用污染量較低的燃料,例如石油氣。