Review and revision of empirical critical loads of nitrogen for Europe

This report contains the scientific background to the review and revision of the empirical critical loads of nitrogen (CLempN) that had been established for Europe in 2011 under the UNECE Convention on Long-range Transboundary Air Pollution. This review uses for the first time gradient studies to evaluate and determine the ClempN. The results, as presented in Table 1 of the Executive Summary, show that in many cases the outer ranges of the CLempN have decreased compared to the 2011 values. The outcomes of this report are of major importance for the protection of N-sensitive natural and semi-natural ecosystems across Europe. This knowledge is used to support European policies to reduce air pollution.