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Relating Occupational Exposure to Persistent Health Effects^{ †}

^{1}

^{2}

^{*}

^{†}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

_{y}, in years) to reach a 10% prevalence of VWF, D

_{y}

_{,10}, as a function of the A(8) value for each population group, i.e.,

_{y}

_{,10}= cA(8)

^{d}

_{y}. For a selected frequency weighting, the relative risk of developing VWF in the first population group compared to the second population group is then estimated using an expression for the daily exposure. The form of the relative risk, RR

_{f}

_{(trial)}, for a trial frequency weighting, f

_{(trial)}, is given by

_{f}

_{(trial)}and a(2)

_{f}

_{(trial)}are acceleration metrics for two power tools or machines that have been frequency-weighted by the trial frequency weighting, and T(1) and T(2) are the mean daily exposure times for the two population groups, respectively. As applied here, Equation (2) requires each population group to operate a single power tool or machine during the workday. In this formulation, the use of A(8) as the daily exposure metric would result in m = 1 and s = 0.5. Alternative metrics for the stimulus are introduced into the calculation through a(1)

_{f}

_{(trial)}and a(2)

_{f}

_{(trial)}, where a different frequency weighting and/or bandwidth for the stimuli, a(1) and a(2), can be defined.

## 3. Results and Discussion

#### 3.1. Suitability of A(8) for Evaluating Daily Exposure Involving Shocks

_{y}and A(8) produce very different prevalences. This is observed irrespective of whether the occupation involved operation of a single or multiple power tools (or machines) during a workday. The implication of this observation, and the result in Section 3.1(b) above, is that the methods for calculating the daily exposure and for combining partial daily exposures in ISO 5349-1:2001, which are given by

_{0}is a reference time for calculating daily exposure (8 h), and T is the mean time (in hours) group members are exposed to vibration with frequency-weighted, r.m.s., acceleration total value a

_{hv}during a workday. For persons operating a range of power tools or machines during a workday, each for different times, the component exposures are summed as in Equation (3) for n tools and machines, where T

_{i}is the time exposed to the ith tool or machine with acceleration total value a

_{hvi}.

#### 3.2. Including Higher Frequencies in the Calculation of Daily Exposure

_{y}, in the two occupations, the relative risk obtained by applying different frequency weightings to these data can be assessed using Equation (2). The result should be unity (i.e., equal risk). For “flat” (i.e., frequency-independent) “weightings” when the daily exposure is constructed according to ISO 5349-1:2001, that is, by specifying m = 1 and s = 0.5 in Equation (2), the magnitude of the relative risk for these two populations is as follows.

_{f(trial)}= 2.7, and so overestimates the risk of exposure to the rock drills compared to the chain saws by a factor of almost three.

#### 3.3. Suggestions for an Acceleration Metric for Shocks

_{f}

_{(trial)}= 1 in Equation (3) for a values of m and s other than those used in ISO 5349-1:2001.

_{f}

_{(trial)}= 1 when m and s assume values other than m = 1 and s = 0.5, a candidate constructed from so-called higher-order mean values may be suitable [13,14]. An attractive metric may be constructed from the time history of the vibration and/or shock(s) that takes the following form:

_{i}. The index r has a value of, typically, 1, 2, or 3, and the K

_{r}are numerical constants chosen so that when the a

_{i}are in units of m/s

^{2}, a approximates the r.m.s. acceleration in m/s

^{2}for a time series that does not contain shocks. In this way, the metric will yield r.m.s. accelerations that are close to those recorded on non-shock power tools and machines using present methods of measurement but will record an increased magnitude compared to r.m.s. for shocks. For a given shock, the increase in magnitude of the metric compared to a non-shock power tool or machine will depend on the value selected for r.

#### 3.4. Relevant Daily Exposure Time for Shocks

## 4. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**MDPI and ACS Style**

Brammer, A.J.; Scholz, M.F.
Relating Occupational Exposure to Persistent Health Effects. *Proceedings* **2023**, *86*, 44.
https://doi.org/10.3390/proceedings2023086044

**AMA Style**

Brammer AJ, Scholz MF.
Relating Occupational Exposure to Persistent Health Effects. *Proceedings*. 2023; 86(1):44.
https://doi.org/10.3390/proceedings2023086044

**Chicago/Turabian Style**

Brammer, Anthony J., and Magdalena F. Scholz.
2023. "Relating Occupational Exposure to Persistent Health Effects" *Proceedings* 86, no. 1: 44.
https://doi.org/10.3390/proceedings2023086044