LPG-powered taxis and minibuses in Hong Kong have produced unintended consequences. Government incentives have brought these alternative-fuel vehicles to the market, but more smog was produced through concentrations of nitrous oxide coming from catalytic converters retrofitted to the vehicles in operation from 2008 through 2012. Unless the vehicles that are driven nearly around the clock are replaced every 18 months, the catalytic converters become fouled, and the vehicles begin emitting extremely high levels of pollution.
