Dust explosions in the process industries have prompted the need for better understanding of dust explosion fundamentals to improve risk assessments. Parameters such as P-max, K(st )and MIE are important to the risk assessment process and depend on dust size, shape, chemical composition etc. Studies often cited particle size (median diameter, d(50)) as a crucial parameter. However, d(50), does not provide information regarding size distribution span (polydispersity), which effects the explosion parameters. This study investigates five aluminum powder blends with similar d(50) and varying polydispersity to demonstrate the weighted mean diameter D (3,2) is a better statistic to associate with MIE. This study highlights the importance of reporting polydispersity, D (32) along with d(50)/median to properly assess the particle size distribution of the dust for accurate explosion risk assessment. (C) 2020 Elsevier B.V. All rights reserved.