Published data on the toxicity of nitrogen dioxide (as a model compound) from five laboratory animal species were utilized to scale the relationship of dose and toxic effect to the human species. A minute volume of inspired air was used as a metabolic scaling factor, predicting a median lethality during the time of exposure of 174 ppm NO2for a 1‐h exposure for people. This work demonstrates a method of predicting effects in people when only data for laboratory animals exist. It also shows the value of planning toxicology studies that utilize several animal species, so that their data may be applied to forecasting the human condition.