The implementation of the proxy data in the ecoinvent database follows usually one of two approaches: one that was developed for ecoinvent v2 about 17 years ago , and an updated one that was used in recent years . Both approaches differ in the exact numbers they use because different years of the environmental reports from Gendorf have been used as data sources, but they also differ in terms of coverage and methodological details. For example, the ecoinvent database v3 connected the proxy Gendorf natural gas and steam inputs to the ecoinvent datasets heat, district or industrial, natural gas and heat, from steam, in chemical industry, respectively. The earlier approach from ecoinvent v2 instead used either only heat, from steam, in chemical industry (about 55 % of cases) or only heat, district or industrial, natural gas (about 45 % of cases). This distinction is critical, since the ecoinvent dataset heat, from steam, in chemical industry includes coal and oil combustion as heat supply, which makes this dataset more than 50 % higher in terms of the climate change impacts than heat, district or industrial, natural gas in the Region Europe (RER) version. The difference between environmental impacts between these approaches is even more extreme when considering other impact categories such human health impacts from particulate matter. The reasoning why sometimes only natural gas and at other times a range of fuels were used as proxy input in the ecoinvent database v2 remains unclear, but it may be related to the different authors who have implemented the proxy approach in different ways.