How the Kowloon Motor Bus fleet has cut pollution in the past two decades has been revealed by its principal engineer, Kane Shum Yuet-hung.
Particulate emissions are down by 92percent, he says, and nitrogen oxide by 57.2percent. This has been achieved by upgrading engines and using less harmful diesel and emission-reduction devices.
Of 3,891 buses in the current fleet, 417 are either Euro IV or V buses using the latest engines.
"We still have around 980 Euro I buses," he added. "But they will be retired by early 2015 while 1,500 Euro II buses are scheduled to complete their service starting in 2014."
Such buses are not suitable for areas such as Causeway Bay, Mong Kok and Tsim Sha Tsui.
Meanwhile, the company is pushing ahead with Euro V diesel, first used in 2008 and which is claimed to contain only 0.001 percent of sulfur. So the punlic is less likely to suffer with fumes.
On buses still using Euro II and III engines, diesel particulate filters may reduce emissions by more than 80percent. The upgraded engines can meet exhaust emission equivalent to a Euro V standard.
The filters mean "the environmental performance can be improved immediately," Shum said. CANDY CHAN