http://fernwaerme-zuerich.ch/index_en.htm http://fernwaerme-zuerich.ch/index_en.htm Was built in 1995, or so it claims, with other kinds of incineration being

http://fernwaerme-zuerich.ch/index_en.htm http://fernwaerme-zuerich.ch/index_en.htm Was built in 1995, or so it claims, with other kinds of incineration being done for >100 years. So 25 years or so. I think that's enough time for a clear effect to show up.