The department said in the past 10 years, the concentration of pollutants in the ambient air has dropped by 43 percent to 62 percent, while the concentration of pollutants recorded for roadsides has fallen by 47 percent to 64 percent,

The department added its data has recorded a significant decline in sulfur dioxide, followed by other pollutants, including fine suspended particulates, respirable suspended particulates, and nitrogen dioxide.

Meanwhile, the department said the number of hours of reduced visibility in Hong Kong has decreased from 1,570 hours in 2004 to 401 hours recorded in 2022, reflecting the city's increasingly blue skies.