All but one of Hong Kong’s more than 18,000 taxis now burn liquefied petroleum gas, but one smog-causing pollutant soars if those vehicles’ catalytic converters are not regularly replaced. Alex Hofford/European Pressphoto Agency All but one of Hong Kong’s more than 18,000 taxis now burn liquefied petroleum gas, but one smog-causing pollutant soars if those vehicles’ catalytic converters are not regularly replaced. Municipal governments all over the world, particularly in developing countries with rapidly growing fleets of cars and choking air pollution, have been rushing over the last few years to force taxis and buses to switch to burning liquefied petroleum gas and compressed natural gas, frequently offering subsidies for them to do so. But one of the early leaders of the trend, Hong Kong, said on Friday that the city’s shift over the last decade to almost complete dependence on LPG for light commercial vehicles had produced unintended […]