The introduction of new safety legislation in Russia has been accompanied by R&D into risk assessment, especially needed when dealing with high-toxicity substances. In the present article, two models for evaluation of the dose absorbed by recipients as a result of instantaneous releases and short-term continuous emissions of toxicant to the atmosphere are developed. The models have the form of definite integrals with Green's function. The numerical problem of evaluation of the absorbed dose with obtained models is reduced to the calculation of single definite integrals. It is shown that under similar initial conditions, the dose absorbed as a result of instantaneous discharge is greater than the dose resulting in a short-term continuous emission of toxicant. An interval approach is developed to estimate the sensitivity of the numerical results to the errors in empirical parameters and variables included in the models. On the base of introduced definitions of interval variables, interval vectors and interval functions, interval estimates for absorbed dose are developed. it is shown that there exists an optimal number of terms in empirical equations with inexact parameters. Numerical examples of interval analysis are given.