This goes back a few years now (2019), so there have been some additional developments, especially with the Bayesian tools. However, some may find this coverage of the concepts useful. If the Bayesian approaches intrigue you, there is a lot out there that you can find and learn and use.
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Mixtures, Partial Pressure, Chemical Activity Coefficients
In evaluating the emissions of volatile and semi-volatile chemicals from mixtures, Raoult’s Law (or Rule, since it so seldom hold true in the real vs IDEAL world!) is a starting point. The next step is to factor in the chemical activity coefficients, that help account for deviations from ideal behavior. Rather than restate it all…
Estimating Ventilation
One of the core parameters in air concentration modeling of chemicals is ventilation. Often, it is Q or the air exhaust volume of the space in meters cubed per minute needed to feed the model. For the two-zone model, the random air velocity “S” is a key parameter needed to calculate Beta, the interzonal air…
Local Exhaust Ventilation and the Near Field-Far Field Model
Recently a graduate student asked me for some help on using the NF-FF model when local exhaust ventilation is present. Since this was for a student, I decided to point out considerations but not give an answer. Perhaps some of this will be helpful to others. In general, the local exhaust ventilation Q(local) is a…
Estimating Consumer vs Occupational Exposures via Scenario Based Modeling
What are the key differences in modeling consumer and occupational (worker) exposure scenarios? I’ve thought about the main factors that can be different. Let me know via comments of you think of more. •Quantity, frequency, duration of chemical use •Formulation differences •Environmental conditions •Volume of work space •Ventilation •Nature of persons exposed These differences can…
Other FREE Exposure Assessment Tools
IH Mod 2.0 and IH SkinPerm are not the only free tools available on the AIHA Web site to help you complete exposure assessments. The additional ones are listed below and are available at this link on the AIHA web site. • IH Exposure Scenario Tool, which guides evaluation of the workplace, specific scenarios and…
But, But … What about DERMAL exposure?
The astute readers here may wonder about modeling dermal exposure. That is not in IH Mod 2.0. However, there are lots of other tools available. One of my favorites for estimating dermal penetration and uptake is IH SkinPerm. It too is an enhanced MS Excel spreadsheet, developed by Wil ten Berge, Daniel Drolet and Rosalie…
What About a Component of a Mixture?
Mixtures present some additional complexities compared to assessment of exposure from pure compounds. For many mixture, one particular component is the main concern. If so, there are ways to undertake that components exposure potential. Do you remember Raoult’s Law from general chemistry? It is pretty simple because it assumes “ideal” behavior. Then, the partial vapor…