This research empirically determined the ²³⁹Pu airborne concentration alpha correction factor for an ADM-300 zinc sulfide detection system via ambient ²²²Rn progeny air sampling using a RADeCO high volume air sampler. Radon progeny air samples were collected on a four inch glass fiber filter and evaluated on both a high purity germanium detector and the ADMē-300 simultaneously using the three count method. These data were analyzed to obtain a loss fraction in the glass fiber filter for the ²¹⁴Bi collected. The ²¹⁴Bi response then was used to estimate a loss fraction for ²³⁹Pu. The ²³⁹Pu airborne concentration alpha correction factor for the ADM-300 detection system was found to be 445 ± 47 dpm ft³ cpm⁻¹ m⁻³ as compared to a previously published correction factor of 500 dpm ft³ cpm⁻¹ m⁻³.