Industrial Hygiene
Exposure Assessment Strategies 

A good Exposure Assessment Strategy is central to a good industrial hygiene (IH) program.
The Department of Defense considers exposure assessment so important to the IH program that they developed the DoD IH Exposure Assessment Model for all the military services to use.
The model is based on the AIHA Exposure Assessment Model.

 ***NEW***  PHC TIP: How to Handle Censored Industrial Hygiene Data
The purpose is to discuss the proper ways to handle censored IH monitoring data when performing IH exposure calculations.

The steps of the DoD IH Exposure Assessment Model include:

DoD IH Exposure Assessment Model from a PHC presentation1.  Define Scope and Support of Resources
2.  Basic Characterization
3.  Similar Exposure Group (SEG)
4.  Develop Worksite Monitoring Plan
5.  Characterize Exposures
6.  Assess Exposures and Provide Control Plan
7.  Reporting and Recording
8.  Re-Evaluation

1. Define Scope and Support of Resources

Make a list of customers, both internal and external.
Meet with organization commanders to identify mission requirements.
Capture organization demographics.
Program and budget for required IH manpower, equipment, and supplies.
Schedule visits to exposure locations for exposure assessments.

2. Basic Characterization

The basic characterization step is the foundation for exposure assessment.
The exposure assessment strategy (EAS) program relies on the basic characterization.
If the basic characterization is weak or flawed, then the program will be weak or flawed.
Basic characterization is where information is gathered to characterize the workplace, the worker force, and the environmental agents.

These basic questions are asked:

1. What are the chemical, physical, and biological agents in the workplace?
2. What are the health effects associated with overexposure to these agents?
3. What are the occupational exposure limits?
4. What are the sources of exposure?
5. What controls are in place?
6. How are the workers organized?
7. What are their job duties?

Example of a  Basic Exposure Assessment and Sampling Spreadsheet external link icon can be found on the AIHA Exposure Assessment Strategies Committee page. Scroll down to "Tools and Links for Exposure Assessment Strategies."

3. Similar Exposure Group

The SEG is a group of employees having the same general exposure profile for agent(s) being studied because of the similarity and frequency of the tasks they perform, the materials and processes with which they work, and the similarity in the way they perform the tasks.
By effectively using well-constructed and defined SEGs, the exposure data can be maximized while minimizing the resources used to get the data. 

4. Develop Worksite Monitoring Plan

Worksite monitoring plans are used to plan and prioritize those SEGs where data need to be collected. 
The objectives of a worksite monitoring plan are:

  • Monitor performance of the exposure controls
  • Collect exposure data to monitor effectiveness of controls on exposure
  • Collect additional data to improve accuracy of exposure estimate
  • Comply with periodic monitoring required by regulatory agencies

5. Characterize Exposures   

Information is captured on frequency and duration of worker exposures and the effectiveness of controls in place during the “characterize exposures” step.
An exposure estimate for workers within a SEG is developed based on:

  • Study protocols
  • Sampling strategy 
  • Sampling methods

After sampling is conducted and all relevant data is collected, samples are submitted for analysis and assessing exposures can begin.

 6. Assess Exposures

During the assessing exposures step, data is collected and compared to an occupational exposure standard.
Determination is then made on whether exposure is acceptable, unacceptable, or more data needs to be collected.      
The determination for how to perform the assessment should be made before a single piece of data is collected.
The assessment criteria should include what occupational exposure standards are used and what is considered to be an acceptable exposure.
Assessing exposures also includes what statistic test(s) will be used and how they will be interpreted. 

Occupational Exposure Limits (OELs)

Select the OEL in accordance with DoD component policy.
If an OEL is not available, seek guidance from technical support offices or use professional judgment based on data collected and document the rationale for the OEL.

Assessment Criteria

Compile all data for the SEG for all exposure routes (e.g., inhalation, skin contact, ingestion).


Interpret the data using statistical tools to assist in making an appropriate judgment of the exposure risk to the workers.

Provide Control Plan

The best control strategy is based on exposure assessment.
A control strategy can be based on an unacceptable exposure identified through an exposure assessment strategy, or can be a proactive plan to ensure the exposure never reaches the point where it creates a hazard. 

Effectiveness of controls can be evaluated for worker exposure for each potential route of exposure (e.g., breathing zone levels with local ventilation operating, noise attenuation of hearing protection, chemical permeation of gloves).

These links may be helpful:

 Respiratory Protection


7. Reporting and Recording

Reporting and recording are essential elements of the EAS to ensure effective communication of findings and the successful continuation of the IH program.
Provide full report and briefing to workplace supervisors and other pertinent personnel with findings and conclusions prioritizing options and recommendations.

Some elements include:

  • Compiled information on each SEG
  • Hazard sources
  • Worker exposures
  • Conditions in violation of OSHA or DoD Component standard
  • Existing controls and their effectiveness
  • Recommended actions
  • Future actions to be taken by IH staff

Record exposures, conditions, and recommendations to be tracked by IH staff.
Identify exposures and medical surveillance recommendations for each SEG to the supervisor and to Occupational Medicine.

8. Re-Evaluation

Repeat the exposure assessment process with the goal of improving previous assessments and continuing to reduce risk to workers. 
Locations should be evaluated at least annually where:

  • Personal exposure to toxic chemicals, harmful physical agents, or biological hazards require medical surveillance
  • Personal exposure to toxic chemicals, harmful physical agents, or biological hazards are controlled by engineering, work practices, or PPE
  • Mandated by Federal or DoD regulations
  • Exposures by ingestion or through skin absorption are significant

Related Documents

 DoD IH Exposure Assessment Model Report - January 2000 (CAC Required) external link icon
 Air Sampling for Asbestos for Comparison to Occupational Exposure Limits
 Air Sampling for Silica with Aluminum Cyclone for Comparison to Occupational Exposure Limits
Seventeenth Interim Report of the Committee on Acute Exposure Guideline Levels 2010 external link icon 

IH Assistance

Army IH provides subject matter experts to help DoD personnel with developing and implementing an EAS.
They can provide assistance and expertise on many elements of the EAS through information provided on this Website, off-site consultation (by phone or e-mail), and onsite consultation. 

Assistance can be provided on what hazards can be expected and the best way to characterize them based on:

  • Process/operations based
  • Hazard (chemical, biological, and physical) based
  • Industrial
  • Garrison
  • Deployment

For information on IH Deployment Support please visit our  IH Deployment Support page

For information on the AIHA EAS Committee, go to:  AIHA Exposure Assessment Strategies Committee external link icon 

Industrial Hygiene Data Interpretation Game (IHDIG)

Are You a Dart Throwing Monkey?

Find out with this Industrial Hygiene Data Interpretation Game (IHDIG) that you can download on your smartphone or tablet PC?
This game illustrates the need for industrial hygienists to use statistical tools every time they interpret sampling data.
The IHDIG is a fun app to help Exposure Assessors train their unconscious data interpretation algorithms to better match a Bayesian Likelihood analysis.
IH DIG for iPad
IH DIG for iPhone
IH DIG for Android

To make sure you are not a Dart Throwing Monkey, you can purchase the tools to help you with your Data Interpretation: