Tell us what good forcing engine switch-off will do, say experts
Scientists and engineers said the proposal to ban idling vehicle engines left unanswered key questions about the extent to which it would reduce air pollution. They urged the government to provide more data to justify the initiative.
'What is the reduction in emissions after the ban? What is the improvement to air quality? These are the most essential questions and the government still owes us the answers in the consultation paper,' said Alexis Lau Kai-hon, an atmospheric scientist at the University of Science and Technology.
Professor Lau said the government should be able to release precise calculations of the expected reductions in emissions of sulfur dioxide, carbon monoxide, nitrogen oxides and respirable suspended particulates. 'I can't judge whether it is a feel-good policy or an effective tool when these questions are still unanswered,' he said.
Lo Kok-keung, of Polytechnic University's mechanical engineering department, said the ban could improve roadside air quality but the information released lacked details.
'Perhaps the government is still unable to come up with a rough estimate and that's why it hasn't put it in the consultation paper,' Mr Lo said.