New Statistical Tool "Supercharges" Traditional IH Data Interpretation
By Jérôme Lavoué and Daniel Drolet
Far from all exposure situations require obtaining quantitative measurement data to reach a decision. But when measurements are required, the considerable day-to-day variations observed in exposure levels render their interpretation challenging. How can an industrial hygienist convince their boss that six measurements all below the occupational exposure limit probably correspond to a potentially harmful situation?
Despite the availability for several decades of a robust theoretical background for this type of analysis—mostly based on the lognormal model and often termed “IH statistics”—few practical tools have been available to support practitioners performing the rather involved calculations needed.
IHSTAT is one of the few available and free IH statistics tools and is arguably the best known in the IH community. It was made available first through the AIHA monograph “A Strategy for Assessing and Managing Occupational Exposures,” which was published in 1998 and was updated with a multilingual capability setup by volunteer Daniel Drolet in 2008.
Industrial hygiene statistics have recently evolved into a new era thanks to Bayesian statistics, which allow practitioners to obtain answers that are more direct and easier to communicate (for example, there is an 84 percent probability that this similar exposure group, or SEG, is overexposed—no need to explain upper tolerance limits anymore). State-of-the-art processing of non-detects is another notable advantage. Data interpretation tools using Bayesian statistics started to appear around 2010. The first was the IH Data Analyst program from Paul Hewett, famous for its “BDA charts” that allowed practitioners to estimate from data a probability associated with each of AIHA’s exposure control categories. Expostats from the University of Montreal appeared in 2014 in the form of web-based and standalone tools, adding the evaluation of exposure heterogeneity within a SEG and analysis of exposure determinants in addition to single SEG analysis.
Our team at the University of Montreal modified the well-known IHSTAT application with Daniel’s help by replacing the embedded equations with a Bayesian engine similar to the one at expostats.ca, allowing the most recent technical developments in Bayesian statistics while maintaining the simple interface favored by many practitioners. Interested parties should note that the Bayesian engine is open source and available to anyone who wishes to create their own tool.
The new tool, called IHSTAT_Bayes, can be found on the AIHA risk assessment tool webpage. The installation of IHSTAT_Bayes is a bit more involved than IHSTAT because of the embedded engine, but then it’s the same familiar user interface. Users input the OEL and measurement values (which can include values below the limit of quantitation) and are presented with traditional distribution parameters (geometric mean and geometric standard deviation), decision statistics (exceedance fraction, 95th percentile or any other percentile, arithmetic mean), and associated confidence limits (70 percent or 95 percent upper limits), enhanced by the addition of the probabilities associated with AIHA’s exposure control categories. The multilingual capability has also been preserved with eight languages included in the recently released version 1.01.
Through the creation of IHSTAT_Bayes, we hope to improve the availability of simple-to-use yet state-of-the-art IH statistics calculators and ultimately better protect workers.
An earlier version of this article appeared in the newsletter of the Canadian Registration Board of Occupational Hygienists. Reprinted with permission.
Coming Soon: Webinar on Ergonomics A Synergist Webinar focused on root cause analysis as a precursor to identifying effective ergonomics solutions will be held on March 14 from 2 to 3 p.m. ET. Presenters Rick Barker, CPE, CSP, and Kristi Hames, CIH, CSP, of VelocityEHS will discuss approaches that ergonomics teams can use to help determine actionable data to highlight the causes of ergonomics issues—for example, gathering operator insights on typical and atypical work processes, linking risk factor exposures to specific elements within a job, and applying root cause analysis tools. Webinar attendees will learn how to prioritize risk factor exposures, identify tools for conducting root cause analysis and communicating the results, define more clearly the causes of musculoskeletal disorders, and leverage internal continuous improvement resources for ergonomics projects.
Thanks to sponsor VelocityEHS, the webinar is free to attend. AIHA updates Synergist Webinar participants’ educational transcripts to reflect their attendance. Register for the webinar.
AIHA Issues New Public Policy Priorities In January, AIHA announced three new public policy priorities that will guide and focus the association’s activities in 2023 and beyond. The three public policy priorities are protecting workers and the public from hazardous noise exposure, protecting workers and the public from thermal stress, and strengthening the occupational and environmental health and safety professional pathway and improving the learning and working conditions of schools.
For other issues not covered by these public policy priorities, AIHA will continue to engage with association members and policymakers. AIHA’s goal is to translate as much of its members’ technical expertise into public policy recommendations as possible to protect more workers and their communities.
For more information on AIHA’s public policy priorities and to access public resources for working with local, state, and federal government representatives on worker health and safety issues, please visit AIHA’s government relations and advocacy webpage.
Registration Cycle Extended for EDA Registry Program After considerable analysis and discussion, the subject matter experts who developed the Exposure Decision Analysis (EDA) Registry program have extended the registration cycle from two years to five years. Current holders of the Registered Specialist: Exposure Decision Analysis credential had their registration extended to five years in duration based on their current cycle start date. The Exposure Decision Registrants page on the AIHA Registry Programs website has been updated to reflect this change. Going forward, those who attain or renew the credential will have a five-year cycle.
The Exposure Decision Analysis Registry program recognizes OEHS professionals who have acquired the skills and knowledge to effectively manage workplace exposure and monitoring data. For more information, visit the AIHA Registry Programs website.
To prepare for the EDA exam, consider AIHA’s “Making Accurate Exposure Risk Decisions” online course, which provides nine contact hours of education for free. Learn more and register for the course on AIHA's website.
Volunteer with AIHA Three AIHA volunteer groups are currently seeking new members: the Continuing Education Committee (CEC), the Content Portfolio Advisory Group (CPAG), and the Conference Program Committee (CPC).
The CEC’s mission is to ensure the highest possible quality for AIHA training programs and educational opportunities for professionals in occupational and environmental health. CPAG seeks new members who are passionate about being at the forefront of emerging trends in the OEHS profession and who would like to help drive content development that helps AIHA members meet current and future challenges. The CPC is responsible for reviewing and selecting education sessions for AIHce EXP, and the committee’s goals include long-range planning for continuous improvement of the technical quality of the annual conference.
Applications to join these groups are due by Wednesday, March 15. Learn more about these and other AIHA volunteer opportunities on the association's website.
New Framework for IH Decision-Making A new competency framework published recently by AIHA is intended to summarize the competencies required to demonstrate awareness, understanding, and the ability to apply core knowledge about the occupational hygiene decision-making framework and process of anticipate, recognize, evaluate, control, and confirm, or ARECC. This new resource, titled “Understanding and Applying ARECC to Occupational and Environmental Health and Safety,” is available to download for free from AIHA's website.
Explore Resources for Academics AIHA has created an academic portal that contains a variety of free educational materials intended to assist academic faculty in supplementing their occupational and environmental health and safety curricula. These topics are designed to enhance students’ learning experience and help them become better prepared as they embark on their careers. Learn more on AIHA's website.
Browse the Vendor Directory
AIHA's Vendor Directory for OEHS Professionals, released in print annually in November, is the most comprehensive publication for sourcing industrial hygiene, safety, and environmental products and services. The online Vendor Directory allows users to search by product, company name, or industry.
Dates and Deadlines March 14 Synergist webinar: “Better Root Cause Analysis Yields Effective Ergonomics Controls.” Registration is free.
March 15 Deadline to apply for positions on AIHA’s Continuing Education Committee, Conference Program Committee, or Content Portfolio Advisory Group.
March 28 AIHA University webinar: “An IH and a Data Scientist Swap Perspectives on Big Data.”
April 13 Florida AIHA 2023 Spring Conference in Altamonte Springs, Florida.
For a complete list of events, visit AIHA's website.