A computer model of radiometric scene simulation for simulated spectra for pollution clouds in complicated environment is proposed. The model is used to introduce the effects of an actual hazardous pollution clouds, such as (CH3)2CHO(CH3)FPO or (CLCH2CH2)2S, into exiting measured background spectra by passive Fourier transform infrared spectrometer (FTIS). The simulated results agree well with the experimental results.