Greatly reducing the pollution of Hong Kong's roadside air is as easy as replacing the fleet of ageing diesel buses with electric ones. The solution is as near as Shenzhen, where a leading producer of such vehicles, BYD, is based. Yet instead of being ahead of the curve, our city is barely on the journey, with KMB, the biggest franchised operator, having just taken delivery of its first battery-powered single-decker. The government has been instrumental in getting this far, and its remaining in the driver's seat is crucial to making the air on our streets less harmful. Putting electric buses on our roads is not as simple as buying them. There has to be investment and careful planning to put in place a recharging network. Safety has to be a priority. Confidence in electric vehicles was shaken in May when three people in a BYD-made taxi died as it burst into flames after being struck by a speeding sports car in Shenzhen. Investigators said the vehicle's design was not to blame, but more than a mainland-produced report will be needed to restore trust. There have been no serious incidents with electric buses, hundreds of which are in use across the mainland, Europe and North America. BYD, the world's largest manufacturer, put the accumulated mileage of the vehicles to July at 8.23 million kilometres. Extensive trials will still be needed for our city to ensure suitability. But given enthusiastic acceptance by public transport companies and passengers elsewhere, there is no reason why the road ahead should not be smooth. A government-funded trial of 36 electric buses is scheduled for next year. That is a minuscule fraction of the 5,798 diesel-powered buses on our roads to the end of last year, more than half of them below acceptable European pollution standards. Our city lags behind other major international centres in upgrading its bus fleet, yet does not lack the financial resources. Environment Secretary Wong Kam-sing has so far said little about the government's pollution-fighting plans. He will be making a sound start if he takes charge on electric buses.