Review of internationally proposed critical levels for ammonia

More than ten years after the recommendation of the updated CLRTAP critical levels for ammonia, new findings on the effects of ammonia on vegetation have been discussed in a workshop in Dessau Scientists dealing with research on effects of ammonia on vegetation and ecosystems and those involved in the monitoring of ammonia in the environment were asked to present their recent research. In total 19 presentations from presenters from nine countries were dealing with a current review, models and future trends of NH3 across Europe in the first session, different ammonia monitoring networks in the second session and with vegetation effects (recent research on different scales) in the third session. The report contains a thematic literature review which was presented as a background document to the workshop and summaries of the talks.