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,要達至符合健康的空氣質素指標,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。