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A mainstay of occupational and environmental health and safety (OEHS) is professionals' need to rely on our education and experience when assessing health risks for workers exposed to environmental agents. In this process, we incorporate our professional judgment into an estimate of the workers' exposure. From this estimate, we decide whether the exposure is clearly unacceptable or acceptable or if uncertainty remains. However, an OEHS professional's judgment is only as good as their experience with the work activities and practices associated with the risk. This is why the profession needs an exposure assessment system and tools to help them make judgments with a higher degree of precision and accuracy.

Implementing an exposure assessment system requires multiple steps. One of the first is establishing an exposure decision criterion. AIHA's publication, A Strategy for Assessing and Managing Occupational Exposures, recommends that OEHS professionals evaluate the 95th percentile of measurements when determining the acceptability of exposures. To help OEHS professionals learn to evaluate and analyze exposure data sets, AIHA offers a free course, "Making Accurate Exposure Risk Decisions." This course provides participants with several statistical tools to aid them in improving their professional judgments. These include two from AIHA's risk assessment toolkit: IH Data Analyst – AIHA by Paul Hewitt and Expostats by the University of Montreal. OEHS professionals should review AIHA's risk assessment tools as they follow the five-step process outlined on AIHA's risk assessment tools webpage, which can be used in exposure assessment systems.

Another key component of an exposure assessment system is formalizing a qualitative exposure assessment process. There are multiple approaches to establishing a qualitative exposure assessment process, such as using prioritization schemes, implementing algorithms, or applying combined approaches. In A Strategy for Assessing and Managing Occupational Exposures, AIHA also recommends that OEHS professionals follow a basic algorithmic approach by assigning each risk a severity or health effect rating, which they multiply by an exposure rating, and then multiplying the resulting value with a certainty rating. The purpose of the qualitative exposure assessment process is to assist OEHS professionals in assessing worker exposures when they have limited resources available and may not be able to perform quantitative exposure assessments for every worker.

OEHS professionals can incorporate another tool into the qualitative exposure assessment process, the Structured Deterministic Model (SDM) 2.0. The SDM 2.0 has the capability to estimate worker inhalation exposures to volatile and semi-volatile chemicals, chemical mixtures, aerosols, and particulates for which monitoring data is not available. One advantage of this tool is that OEHS professionals can use it to find the controlling chemicals in products. This Microsoft Excel-based tool also includes a database of more than 600 chemicals, which allows users to automatically populate fields instead of manually inputting every chemical. They may add chemicals specific to their own applications to the tool's database as well.

If you're interested in learning more about the SDM 2.0, AIHA University is hosting a webinar at 1 p.m. Eastern time on July 24, titled "Using the SDM 2.0 to Assess Real-World Situations." The instructors—Susan Arnold, PhD, CIH, FAIHA, Mark Stenzel, FAIHA, and myself—aim to familiarize participants with the SDM 2.0 and teach them how to apply the tool in common workplace situations. In addition to this webinar, you can view several videos on the SDM 2.0 hosted by the Exposure Science and Sustainability Institute.