Updated Modeling Tool Available from AIHA.org

Published Sept. 10, 2018

By Thomas W. Armstrong and Daniel Drolet

IH Mod 2.0, a free suite of mathematical models used to estimate air concentrations of chemicals, is now available from the AIHA Exposure Assessment Strategies Committee’s web page. IH Mod 2.0 is an updated version of a Microsoft Excel spreadsheet that implements Monte Carlo Simulation, or MCS, a useful statistical technique for situations that involve variable or uncertain data.

Insights from MCS can guide industrial hygiene decisions related to the severity of an exposure, the uncertainties that affect an exposure assessment, and the prioritization of control measures for mitigating exposures. Proprietary MCS software is often expensive and has steep learning curves. Users of proprietary tools must also budget for equation setup and verification time. IH Mod 2.0’s usability and range of models may increase the use of mathematical modeling worldwide. Individuals can currently use the models in English, French, Serbo-Croatian, or Japanese. Spanish, German, and Italian language options are coming soon.

A support file for IH Mod 2.0 is also available from the EASC web page and includes a spreadsheet to estimate pool generation rates for liquid spills, a conversion tool for units of measure, examples of generation rate estimation, a “bootstrap” tool for estimating summary statistics from data, estimation of the evaporation constant α for the exponentially decreasing emission rate models, and links to other resources. The support file is an evolving document and will be updated periodically.

Other modeling tools available from the EASC web page include IH SkinPerm, which can be used to estimate dermal absorption. For more information about MCS, read the article “Making Decisions with Uncertain Data: Practical Examples of Monte Carlo Simulations” in the January 2015 issue of The Synergist.

Thomas W. Armstrong and Daniel Drolet are members of the AIHA Exposure Assessment Strategies Committee. Together, they created IH Mod 2.0 and its predecessor, IH Mod.