The EPA pointed out that two-stroke motorcycle engines are designed such that an oil-lubricant mixture enters and burns in engine cylinders during intake and exhaust of air. Visibly polluting blue/ gray smoke is easily produced from incomplete combustion. A two-stroke motorcycle emits 17 to 18 times more hydrocarbons (HCs) and twice the carbon monoxide (CO) than those emitted by a four-stroke motorcycle. Emission standards for new vehicles have become stricter since 2004 to encourage manufacturers to cease production of two-stroke motorcycles. For in-use vehicles, since 2008 subsidies have been offered to encourage phaseouts. However, data showed that there were roughly 1.03 million two-stroke motorcycles nationwide as of the end of March 2018. These vehicles present a big challenge for air pollution control and hence the dire need of taking them off the roads as soon as possible.

The EPA discovered that during the implementation of subsidies for phase-outs, people tended to discard their two-stroke motorcycles with recyclers at the end of the year. This made it difficult for recyclers to coordinate and recycle all vehicles before the year end. After review, the regulations were revised so that the year applicants would be subsidized would be based on the date of discarding. Also, the original regulation demanding vehicle inspection records for the subsidy application has been removed, because owners are less willing to get rid of old two-stroke motorcycles due to a lack of records of regular inspections.

The EPA stated that the amount for subsidies for the phase-out of two-stroke motorcycles and purchase of new electric bicycles will decrease year after year. For 2018, NT$1,000 is provided for phase-outs only, NT$4,000 to 6,000 for both phase-out and purchase (depending on the model of the new vehicles), and NT$1,500 to 3,500 (depending on the vehicle models) for purchase only. Local governments will offer extra subsidies as well. The subsidies will be applicable until 2020.