Background Reference Documents

Functional Requirements for IH/OEHS Systems provide basic and advanced requirements one may need in a computer database system to make informed exposure judgments. This database tool affords one the ability to incorporate both qualitative and quantitative assessments.

Volunteers developed product Exposure Modeling Toolbox with the AIHA and Product Stewardship Society. Those looking for introductory and comparative information regarding the selection, inputs, outputs, and differences between models explored by the team and found to be useful in assessing exposures to humans from products are for use by those looking for introductory and comparative information regarding the selection, inputs, outputs, and differences between models explored by the team. It should not be considered exhaustive, as many models were explored but found to be inaccessible to the general member (fee-based, other languages, etc.), or were unwieldy or could not be validated as functional. Members are encouraged to participate in the member societies and raise awareness of new or unreviewed models to the AIHA Exposure Assessment Strategies Committee for further consideration.

IH/OEHS Apps & Tools

The following software tools provide the practicing industrial hygienist with quick and easy access to the information necessary to evaluate exposure profiles and determine if the exposures are acceptable, not acceptable or if more data is needed to determine acceptability. Like all software tools, the results depend on proper tool use and quality data inputs appropriate to the exposure scenario. Users are encouraged to gain expertise in specific tool use via a study of the appropriate references as listed and participation in appropriate professional development courses.

Legal Notice: You may not create derivatives of the Apps and Tools or otherwise reverse engineer, disassemble, or decompile the Apps and Tools or otherwise attempt to derive the source code of the Apps and Tools unless source code access is expressly permitted by the American Industrial Hygiene Association. The unauthorized use of these Apps and Tools is illegal and may result in civil or criminal penalties under the U.S. Copyright Act or other applicable copyright laws.

Macro Issues?

In this video, explore the new security updates coming to Microsoft Office products starting April 2022 that are changing the way Macro-Enabled documents are going to work. Explore which apps are affected and their timeline for the rollout of the new features as well as the look and feel of the new warning screens. Learn More.

Common Questions

TOOLS For the Practicing Industrial Hygienist

These tools are all free and are regularly updated. Several are available in multiple languages.

STEP 1: Data Collection

IH/OEHS Exposure Scenario Tool (IHEST)TM (latest version: 15, 2014) guides the assessor by collecting general information about the workplace, specific scenarios, and agents(s), providing cues for measuring or estimating the important determinants of exposure as generation and ventilation rates. It also prompts the user to specify the type of engineering controls; this information is needed later when making initial judgments by applying the SDM2.0TM tool (Refer to Step 3 below). Authors/Developers: Susan Arnold, Mark Stenzel, and Daniel Drolet. Access a free training video courtesy of ESSI.

STEP 2: Basic Characterization

Basic Exposure Assessment and Sampling Spreadsheet is an Excel-based template for entering air and noise sampling data.

NPT-ODT Estimator is a supplemental tool for the Odor Thresholds for Chemicals, 4th edition text. Use this Excel spreadsheet to estimate the concentration of a compound's odor detection threshold when no published threshold exists and the compound is not biologically reactive or acts by a specific toxic mechanism. Developed by Patrick Owens, CIH, CSP (2014).

STEP 3: Preliminary/ Initial Exposure Assessment (Tier 1)

SDM2.0TM is an Excel-based, user-friendly tool for estimating airborne concentrations that represent potential occupational inhalation exposure to volatile and semi-volatile chemicals and chemical mixtures, aerosols, particulates, and fibers. It includes expanded functionality compared to its predecessor, the Checklist Tool, and a more visually informative report page. The SDM 2.0TM Support File provides important guidance for using the SDM 2.0TM appropriately, and additional calculators and conversion tools. It can be applied in just a few minutes using readily available information and is significantly more accurate than subjective, intuitive judgments. The user is referred to Chapters 6, 23, and 26 of A Strategy for Assessing and Managing Occupational Exposures, 4th edition, AIHA Press. Access a free training video courtesy of ESSI.

SDM2.0TM exposure assessment capabilities beyond those included in the prior checklist tool include the following:

  • Assesses exposure of overall mixtures and their individual chemical components
  • Assess exposure under non-ambient conditions
  • Expands exposure control category (ECC) 4 into 5 additional categories based on exposure and expands the health risk ranking (HRR) categories from the current 5 levels to seven levels. These modifications greatly enhance risk assessment, risk management, and risk communication efforts.
  • The tool includes a chemical database comprised of over 600 chemicals allowing the practitioner to populate required input fields that had to be populated manually in the prior checklist tool. And it includes a user chemical database that allows the user to include chemicals unique to their specific applications.
  • Provides a mechanism for utilizing existing quantitative measurements collected on a component of a mixture to calculate the corresponding exposure to the remaining non-measured components.
  • Saves the inputs and output as a 1-page report as a pdf


  • Can be used by corporate and consulting companies to develop exposure estimates for regulatory compliance, health and safety program management, emergency response planning, or for toxic tort cases.
  • Can be used by organizations to estimate the measure of health risk for a worker or group of workers


Click on the link and register to begin the licensing process. Once the license agreement is completed, the tool can be downloaded for free.

STEP 4: Refined Assessment (Tier 2)

  • IHMODTM (latest version: 2.016, June 2023) is an Excel-based mathematical modeling spreadsheet similar to the previous IHMOD 1.0, which is now obsolete. IHMODTM gives the user a choice between running the model in deterministic (point value parameters as was in IHMOD 1.0) or in Monte Carlo Simulation mode, with choices of distributions of parameter values right in MS Excel with no other software needed. An IHMOD Support File (latest version: 1.07, October 2021) is also available. It includes useful information about IHMODTM. A spreadsheet tab to estimate liquid spill pool generation rates via the Hummel-Fehrenbacher equation, units of measure conversion tool, examples of generation rate estimation, a “Bootstrap” procedure tool, a summary of approaches to estimate ALPHA for the exponentially decreasing emission rate models, and some links to other resources. Please note that the support file is evolving and will be updated periodically with new information. Authors/Developers: Thomas W. Armstrong, Daniel Drolet and Michael Jayjock. Check back here for updates.
  • IHSkinPermTM (latest version: 2.4, October 2021) is an Excel application for estimating dermal absorption. Basic knowledge of Excel is all that is needed to operate IH SkinPermTM. IH SkinPermTM is a work product of the AIHA Exposure Assessment Strategies Committee (EASC) and the Dermal Project Team (DPT) in collaboration with Wil ten Berg, author of the original SkinPerm model. Although various parameters and data outputs have been explained or defined in IH SkinPerm through comments tagged on individual fields, users are encouraged to read Chapter 13 of the Mathematical Models for Estimating Occupational Exposure to Chemicals, 2nd edition, AIHA Press, 2009, C. Keil Editor. This is a useful reference for understanding the science and terminology associated with skin permeation. Authors/Developers: Wil ten Berge and Daniel Drolet. You can find the details and description of the mathematical model and workbook here.
  • ODHMODTM (latest version: 1.02, December 2021) is a Microsoft® Excel workbook for predicting the oxygen content trends in environments where inert gas releases may lead to asphyxiation risks. ODHMODTM uses a Near Field-Far Field approach and estimates the oxygen concentration percent by volume and as mmHg partial pressure over time in the two zones. In addition to output graphs, the time required for reaching a target level is provided. Results can be compared to reference values for typical human body reactions due to Oxygen Deficiency Hazards and the need for mitigation measures. Examples guide input values for multiple industrial scenarios. ODHMODTM has a user-friendly multilingual interface like several other AIHA tools (More info ... watch the PowerPoint file). This workbook is a product of a collaboration between AIHA and Università Degli Studi di Brescia (Italy). Authors/Developers: Elena Stefana, Filippo Marciano, Thomas W. Armstrong, and Daniel Drolet. You can find the details and description of the mathematical model and workbook here.
  • Dermal Risk Assessment Model (DRAM)TM (latest version: 1.00, February 2022) tool provides a systematic screening evaluation of the relative risks of dermal exposure to a material and may be especially useful for the purposes of prioritizing additional analysis for specific materials or scenarios. This MS Excel spreadsheet tool includes HELP screens for its deterministic (single value inputs) and Monte Carlo Simulation (distributions of input values). It runs only in MS Excel (with macro-enabled mode) but requires no other software.
    The tool uses information about the nature of the dermal toxicity and categorical choices for exposure factors such as dermal contact area, contact frequency, dermal retention time, dermal concentration/loading and dermal penetration potential. The factors are used in an algorithm to estimate the risk and plot it on risk grid. As such, an understanding the tool’s inputs as defined (including potential limitations) and resulting outputs can guide the user to decisions about controls or for more refined risk assessments. However, it is also important for the user to carefully read the available HELP screens, and to have an initial basic understanding of the definitions and inputs used and the potential complexities of the input selection process. When in doubt, an expert should be consulted regarding the selection of inputs and outcomes of the tool. Authors/Developers: Jennifer Sahmel, Daniel Drolet, and Susan Arnold.
  • FR Assessment ToolTM. Understanding, evaluating, and selecting FR clothing can be a challenge for many Health and Safety (H&S) professionals. Lack of recognition of the need for FR clothing leaves many workers without proper protection. Yet requiring it where it is not needed can be expensive and may unnecessarily add to the employee heat load and employee complaints. Therefore, it is important to accurately assess a workplace to determine the need for FR clothing. This tool is a simple Excel spreadsheet that H&S professionals can use to help them assess a work area to more accurately make decisions about the need for FR clothing. Authors/Developers: Cheryl Dubois, Allie Fletcher, Curtis Hinz, Kevin Mahoney, Georgi Popov (on behalf of the Protective Clothing & Equipment Committee, copyright assignment 2021).
  • The UNIFAC Calculator was developed in 1996 by Bruce Choy and Danny D. Reible in the Departments of Chemical Engineering at the University of Sidney and Louisiana State University, respectively. It is an older but very helpful tool that applies the UNIFAC approach for determining activity coefficients. To use the calculator, enter the temperature of the mixture and the components of the mixture. The calculator comes with a few preloaded chemicals. Other chemicals must be entered and built using the “Define” application of the program. UNIFAC then uses component units of the molecule to determine activity coefficients.

STEP 5: Refining/Validating the Exposure Assessment

IHDA-AIHATM is a free version of the IH Data Analyst program ( designed for EHS students and professionals taking classes or professional development courses on the analysis and interpretation of occupational exposure measurements. The program calculates the standard descriptive and decision statistics recommended by the AIHA, and includes goodness-of-fit procedures and graphs, several methods for analyzing datasets containing non-detects, and Bayesian Decision Charts, which were designed to assist in the selection of the most appropriate AIHA exposure control category. Author/Developer: Paul Hewitt. Those using IHDA-AIHATM for paid work on behalf of their client or employer are asked to show their appreciation to AIHA and the program's author by donating $100 USD to the American Industrial Hygiene Foundation scholarship program for each installed copy.

is a free toolbox of web applications from the University of Montréal for the interpretation of industrial hygiene measurements using the lognormal distribution. Tool1, 2, and 3 from Expostats answer the following questions, respectively: is my similar exposure group overexposed? Is my similar exposure group homogenous? What factors are associated with exposure levels in my dataset? All calculations are performed using Bayesian statistics and results are presented in the intuitive probabilistic form. An offline version is also available. ExpostatsTM is presented in an article from the Annals of Work Exposure and Health which was awarded the 2021 Bedford prize. We warmly welcome any questions, suggestions or remarks.

IHSTATTM is an Excel application that calculates various exposure statistics, performs goodness of fit tests, and graphs exposure data. Multiple languages are available. The book “A Strategy for Assessing and Managing Occupational Exposures” is intended to accompany this tool. It provides critical detail on the use and interpretation of the various statistical outputs. Authors/Developers: John Mulhausen and Daniel Drolet.

The links below will show you how to adjust the macros settings in your version of Excel if needed.

IHSTAT_BayesTM (latest version: 1.00, June 2022) is an Excel-based application that calculates various exposure statistics using a Bayesian model. It is intended as an enhanced version of IHSTAT including, thanks to the Bayesian engine, optimal treatment of non-detects, and the probabilities associated with each AIHA exposure control category. Multiple languages are available. The book “A Strategy for Assessing and Managing Occupational Exposures” is intended to accompany this tool. It provides critical detail on the use and interpretation of the various statistical outputs. Author/Developer: Daniel Drolet.


Toxico-kinetic Extended Shift OEL Adjustment

Options for adjusting OELs for extended work shifts include the Brief and Scala model, regulatory models (e.g, OSHA), and more. One of the options for unusual/extended work shifts was published by Hickey and Reist and considers the biologic half-life as well as the work schedule. The download link below is for an MS Excel spreadsheet that implements the Hickey and Reist approach, as published by Armstrong et al. The spreadsheet has four tabs: 1. known half-life, 2. unknown half-life, 3. documentation and 4. examples. Also note that this spreadsheet does not use macros or VBA code.

Download HERE.

REFERENCES are in the Documentation tab of the spreadsheet.