Polymer nanofiber mats with various morphology structures (nanofiber, beaded-nanofiber, and composite particle/nanofiber) were prepared by electrospinning for application to aerosol particle filtration. The filtration performance of these polymer nanofiber mats was evaluated based on quality factors generated from measurement of penetration through the filter by sodium chloride (NaCl) aerosol particles ranging from 20 to 300 nm. These filtration test results showed that the quality factors of beaded-nanofiber filter mats were the best, even though the aerosol particle penetration of them was the highest of the morphology structures. The results of the present study show that morphology optimization of polymer nanofibers is an effective method for improvement of filtration performance, and it must be the future direction for development of new filtration media. (C) 2010 Elsevier B.V. All rights reserved.