Virtual ergonomics (VE) tools have had an impressive impact on the automotive, aviation, and defence industries. Despite the progress made in the last four decades, the tool complexity and application potential in other industries continues to invite improvement opportunities. Firefighting is an occupation with a high musculoskeletal injury burden that can benefit from innovative VE tools. This dissertation aims to: 1) improve VE tools for traditional and novel applications, and 2) identify injury risk to firefighters during fire suppression tasks. This dissertation begins by proposing a set of joint-specific and whole-body posturing guidelines for the manual manipulation of digital human models (DHMs) in the context of automotive manufacturing. Simulation accuracy improved with the implementation of posturing guidelines. These findings are useful instructions for virtual simulation ergonomists, software developers of posture prediction algorithms, and those charged with determining manufacturing ergonomics protocols. Descriptive ergonomic analyses of 48 firefighters in full bunker gear performing three common fire suppression tasks were then performed to identify the required ergonomic action needed for these tasks. Next, two VE tools (Jack and 3DSSPP) and Microsoft Kinect® 3D motion capture data were used to conduct an in-depth analysis of the most difficult task, the high-rise pack lift. The analysis included developing a methodology for modeling the external loads due to personal protective equipment. In addition to describing the firefighter injury risk exposure during common fire suppression tasks, the results highlight the strengths, limitations, and areas for further improvement of VE technology. Overall, VE tool improvements include suggesting guidelines for manual DHM posturing, understanding the strengths and limitations of using 3D motion capture gaming technology for posturing DHMs, and developing strategies to account for external loads due to personal protective equipment. Following these improvements, VE technology shows promise as an ergonomic assessment tool for firefighters. / Thesis / Doctor of Philosophy (PhD) / Virtual ergonomics (VE), which uses digital human models in virtual workstations, allows for efficient and detailed ergonomic assessments of tasks that are otherwise difficult or impossible to perform. However, more research is needed to identify tool improvements for both traditional and new applications. This work proposes, evaluates, and ultimately recommends a set of postural guidelines for the posturing of digital human models to ensure accurate simulation and subsequent assessment of real assembly-line worker movement patterns. Next, firefighter ergonomics, a relatively new application for VE tools, is introduced by first describing the injury risks associated with common fire suppression tasks. The strengths, limitations, and potential of applying VE tools to firefighting ergonomics are then highlighted through an example of simulating the high-rise pack lift task using two VE tools. Overall, the results contribute to the evolving field of VE by challenging current methodologies and highlighting new opportunities for VE tools.