Measurements of transmittance through dust and debris clouds generated by explosions and moving vehicles from five field tests involving 120 trials were analyzed to determine the degree to which transmittance is wavelength dependent. Statistical tests to determine whether the amounts of time transmittance were reduced to specified levels that were significantly different for various wavelengths revealed, in general, no consistent wavelength dependence. Relationships between the extinction coefficient for IR spectral and visible regions have been established for specific explosive types and soil conditions involved in some of these tests.