UNECE Crit: Critical Load database (UNECE-LRTAP)

The first critical loads defined and calculated were for acidity and in the negotiations of the 1994 Oslo Protocol a so-called sulfur fraction had been used to derive a critical deposition of sulfur from the acidity critical load. In the negotiations leading to the 1999 Gothenburg Protocol, nitrogen became the focus and thus new critical loads had to be defined.