[en] The paper summarizes model evaluation studies conducted for the MATHEW/ADPIC transport and diffusion models during the past ten years. These models support the US Department of Energy's Atmospheric Release Advisory Capability, an emergency response service for atmospheric releases of nuclear material. Field campaigns involving tracer releases used in these studies cover a broad range of meteorology, terrain and tracer release heights, the three most important aspects of estimating air concentration values resulting from airborne releases of toxic material. Results of these studies show that these models can estimate air concentration values within a factor of 2, 20% to 50% of the time, and a factor of 5, 40% to 80% of the time. As the meteorology and terrain become more complex and the release height of the tracer is increased the accuracy of the model calculations decreases. This band of uncertainty appears to represent correctly the current capability of these models. (author)