Using the Right Green Yardstick: Why Process Mass Intensity Is Used in the Pharmaceutical Industry To Drive More Sustainable Processes

There have been a many publications and much discussion about green metrics. While many have been proposed, The American Chemical Society Green Chemistry Institute's Pharmaceutical Roundtable has chosen process mass intensity (PMI) as the key, high-level metric for evaluating and benchmarking progress towards more sustainable manufacturing. This paper provides the philosophical and technical arguments on why PMI was chosen above other related metrics such as E factor or atom economy.