Wu says that in the US, Japan and South Africa, getting steam engines back on the rails has required special permits from environmental authorities which exempt these artifacts from the usual air-pollution regulations.
他說，日本、美國、南非等國家的經驗是，蒸汽火車行駛由環保單位發給特許執照，使古物復駛不受一般空氣汙染法規的規範。