Hybrid procedure to determine optimal workforce without noise hazard exposure

Hearing loss is a major occupational health problem among industrial workers. Repetitive exposure to loud noise increases the risk of hearing loss. An administrative noise control such as job rotation can help to reduce workers’ daily noise exposures. In a case where noise levels are excessively high, it is often necessary to assign additional workers to the current workforce to alleviate daily noise exposures that individual workers receive. This paper presents four solution algorithms (three approximations and one exact) to determine a minimum number of workers and their work assignments to attend noisy workstations without noise hazard exposure (that is, daily noise exposure does not exceed 90 dBA). Then, a hybrid procedure which utilizes the four algorithms successively is proposed to improve the solution procedure. Based on a computational experiment on 300 test problems, it is found that the hybrid procedure outperforms all four algorithms (when utilized separately) and is able to find an optimal solution for 88% of the test problems.     

Pilot task-based assessment of noise levels among firefighters

Purpose

Over one million American firefighters are routinely exposed to various occupational hazards. While efforts have been made to identify and reduce some causes of injuries and illnesses among firefighters, relatively little has been done to evaluate and understand occupational noise exposures in this group. The purpose of this pilot study was to apply a task-based noise exposure assessment methodology to firefighting operations to evaluate potential noise exposure sources, and to use collected task-based noise levels to create noise exposure estimates for evaluation of risk of noise-induced hearing loss by comparison to the 8-hr and 24-hr recommended exposure limits (RELs) for noise of 85 and 80.3 dBA, respectively.

Methods

Task-based noise exposures (n = 100 measurements) were measured in three different fire departments (a rural department in Southeast Michigan and suburban and urban departments in Northern California). These levels were then combined with time-at-task information collected from firefighters to estimate 8-hr noise exposures for the rural and suburban fire departments (n = 6 estimates for each department). Data from 24-hr dosimetry measurements and crude self-reported activity categories from the urban fire department (n = 4 measurements) were used to create 24-hr exposure estimates to evaluate the bias associated with the task-based estimates.

Results

Task-based noise levels were found to range from 82 to 109 dBA, with the highest levels resulting from use of saws and pneumatic chisels. Some short (e.g., 30 min) sequences of common tasks were found to result in nearly an entire allowable daily exposure. The majority of estimated 8-hr and 24-hr exposures exceeded the relevant recommended exposure limit. Predicted 24-hr exposures showed substantial imprecision in some cases, suggesting the need for increased task specificity and highlighting the variability of firefighting noise exposures.

Conclusions

The results indicate potential for overexposure to noise from a variety of firefighting tasks and equipment, and suggest a need for further exposure characterization and additional hearing loss prevention efforts.

Relevance to industry

Firefighters may be at risk of noise-induced hearing loss, which can affect their fitness for duty and ability to respond effectively to emergencies. The results of this study suggest that additional efforts at hearing loss prevention among firefighters are warranted.     

Occupational exposure to noise and hearing thresholds among civilian aircraft maintenance workers

High noise exposure is anticipated to be present in the aircraft maintenance operations in civil aviation sector. The objective of the present study is the assessment of noise exposure and hearing threshold of the aircraft maintenance workers in this sector. Noise levels were measured in the aircraft hangers and in the workshops at a main international airport in Saudi Arabia. Two hundred aircraft maintenance workers were subjected to pure tone audiometry. The average L_eq,8h at most of the aircraft maintenance operations was considerably high and most of the workers (89.5%) were exposed to noise levels ≥85 dBA. Frequency analysis of sound pressure levels revealed that the contribution of the octave bands 1, 2 and 4 kHz to the overall noise level was high. The audiograms of the examined workers showed significant hearing impairment as compared to non-noise-exposed Saudi employees. Although the observed excessive noise levels can cause hearing loss, the effect among the studied aircraft maintenance workers was mild. This might be attributed to the usage of hearing protection devices, the intermittent nature of the workers' exposure to noise and job rotation. Statistical analysis revealed significant association of both age and usage of hearing protectors with hearing loss. The effect of exposure duration on hearing loss was also detected.     

Occupational noise exposure of fishermen aboard small and medium-scale fishing vessels

There is little information about occupational noise exposure of fishermen working on small and medium-scale fishing vessels, mainly because of the difficulty of conducting noise exposure surveillance in such occupations. The objective of the current study was to evaluate the exposure of this group of workers to occupational noise using a combined measurement and questionnaire approach. Sound pressure levels were measured aboard 24 fishing vessels at all working or resting locations and during speeding and slow-down moods of the engine. The average existence times of the crew at such locations were collected using a questionnaire. The average daily noise exposure levels (L_EP,d,8h) for engine mechanics in all vessel types (91.2–94.3 dBA) and the tiller operators in gill/trammel and purse seining vessels (84.7–88.4 dBA) exceeded the NIOSH recommended exposure limit of 85 dBA. Other crew members were found to be exposed, on average, to daily noise exposure levels slightly lower than the recommended one (81.6–83.5 dBA). However, direct personal dosimetry for five crew members revealed daily noise exposure levels 1.1–5.1 dBA higher than the calculated averages, which might be attributed, partly, to sources of uncertainty. The results of this study suggest that small and medium-scale vessels fishermen are at high risk of NIHL, calling for development and enforcement of suitable interventions for hearing protection of the workforce of this sector.     

A hybrid genetic algorithm and bacterial foraging approach for global optimization

The social foraging behavior of Escherichia coli bacteria has been used to solve optimization problems. This paper proposes a hybrid approach involving genetic algorithms (GA) and bacterial foraging (BF) algorithms for function optimization problems. We first illustrate the proposed method using four test functions and the performance of the algorithm is studied with an emphasis on mutation, crossover, variation of step sizes, chemotactic steps, and the lifetime of the bacteria. The proposed algorithm is then used to tune a PID controller of an automatic voltage regulator (AVR). Simulation results clearly illustrate that the proposed approach is very efficient and could easily be extended for other global optimization problems.     

A harmony search algorithm for high-dimensional multimodal optimization problems

Harmony search (HS) and its variants have been found successful applications, however with poor solution accuracy and convergence performance for high-dimensional (≥200) multimodal optimization problems. The reason is mainly huge search space and multiple local minima. To tackle the problem, we present a new HS algorithm called DIHS, which is based on Dynamic-Dimensionality-Reduction-Adjustment (DDRA) and dynamic fret width (fw) strategy. The former is for avoiding generating invalid solutions and the latter is to balance global exploration and local exploitation. Theoretical analysis on the DDRA strategy for success rate of update operation is given and influence of related parameters on solution accuracy is investigated. Our experiments include comparison on solution accuracy and CPU time with seven typical HS algorithms and four widely used evolutionary algorithms (SaDE, CoDE, CMAES and CLPSO) and statistical comparison by the Wilcoxon Signed-Rank Test with the seven HS algorithms and four evolutionary algorithms. The problems in experiments include twelve multimodal and four complex uni-modal functions with high-dimensionality.Experimental results indicate that the proposed approach can provide significant improvement on solution accuracy with less CPU time in solving high-dimensional multimodal optimization problems, and the more dimensionality that the optimization problem is, the more benefits it provides.     

Whole body vibration exposures in bus drivers: A comparison between a high-floor coach and a low-floor city bus

Low back pain (LBP) is common in occupational bus drivers and studies have shown a dose–response relationship between whole body vibration (WBV) exposure and LBP. Bus design may be an important factor in determining the WBV exposure a bus driver receives. The purpose of this study was to determine whether differences exist in WBV exposures between two buses commonly used in long urban commuter routes: a high-floor coach and a low-floor city bus. Each bus was driven over a standardized test route which included four road types: a newer smooth freeway, a rougher old freeway, a city street segment, and a road segment containing several speed humps. WBV exposures were calculated per ISO 2631-1 (1997) and ISO 2631-5 (2004) standards. WBV exposures were significantly higher in the high-floor coach bus on the road segment containing speed humps. There were primarily small differences between buses in WBV exposures encountered on the city street and freeway segments. With respect to the ISO 2631-1 and European Union's A(8) and VDV(8) action limit values, both buses could be operated on the smooth freeway without exceeding the 8-hour action limits but would have to be operated less than 8 h when operating on the other road types. On average, the seats only attenuated 10% of the floor transmitted vibration and amplified the vibration exposures on the speed humps. Due to the low vibration attenuation performance of the bus driver's seat, evaluating different types of seats and seat suspensions may be merited.Relevance to industryLow back Pain (LBP) is one of the leading causes for workplace disability; therefore, it would be beneficial for employers and workers to minimize WBV exposures resulting in LBP. To reduce WBV exposures, buses should be assigned to appropriate routes and drivers should rotate across routes to vary continuous and impulsive exposures.     

Hybrid strategy for selecting compact set of clustering partitions

The selection of the most appropriate clustering algorithm is not a straightforward task, given that there is no clustering algorithm capable of determining the actual groups present in any dataset. A potential solution is to use different clustering algorithms to produce a set of partitions (solutions) and then select the best partition produced according to a specified validation measure; these measures are generally biased toward one or more clustering algorithms. Nevertheless, in several real cases, it is important to have more than one solution as the output. To address these problems, we present a hybrid partition selection algorithm, HSS, which accepts as input a set of base partitions potentially generated from clustering algorithms with different biases and aims, to return a reduced and yet diverse set of partitions (solutions). HSS comprises three steps: (i) the application of a multiobjective algorithm to a set of base partitions to generate a Pareto Front (PF) approximation; (ii) the division of the solutions from the PF approximation into a certain number of regions; and (iii) the selection of a solution per region by applying the Adjusted Rand Index. We compare the results of our algorithm with those of another selection strategy, ASA. Furthermore, we test HSS as a post-processing tool for two clustering algorithms based on multiobjective evolutionary computing: MOCK and MOCLE. The experiments revealed the effectiveness of HSS in selecting a reduced number of partitions while maintaining their quality.     

A study on hybrid random signal-based learning and its applications

In this paper, we propose three effective hybrid random signal-based learning (RSL) algorithms which are a combination of RSL with simulated annealing (SA) and a genetic algorithm (GA) to obtain a global solution that can be used in combinatorial optimization problems. GAs are becoming more popular because of their relative simplicity and robustness. GAs are global search techniques for non-linear optimization, but they are not good at fine-tuning solutions. RSL is similar to the reinforcement learning of neural networks using random signals. It can find an accurate solution in local search space. However, it is poor at hill-climbing, whereas simulated annealing has the ability to perform probabilistic hill-climbing. Therefore, combining them yields effective hybrid algorithms, i.e. hybrid RSL algorithms, with the merits of both. To check the generalization ability of the proposed algorithms, the optimizations of several benchmark test functions are considered, while the optimization of a fuzzy logic controller for the inverted pendulum is detailed to show the applicability of the proposed algorithms to fuzzy control.     

Metaheuristic approaches to grouping problems in high-throughput cryopreservation operations for fish sperm

High-throughput cryopreservation operations of fish sperm is a technology being developed by researchers today. This paper first formulates a grouping problem in high-throughput cryopreservation operations of fish sperm and then develops a heuristic and four metaheuristic algorithms for its solution. The heuristic is modified from one originally proposed for the assembly line balancing problem. The four metaheuristic algorithms include simulated annealing (SA), tabu search (TS), ant colony optimization (ACO), and a hybrid differential evolution (hDE). For each metaheuristic algorithm, four different initialization methods were used. For both SA and TS, five different neighborhood solution generation methods were also studied. Real world data collected from a high-throughput cryopreservation operation was used to test the effectiveness of algorithms with different initialization and neighborhood solution generation methods. For comparison, a base line of grouping by processing order was also established. The results indicate that: (i) all algorithms performed better than the base line; (ii) using the result of the modified heuristic as the initial solution of metaheuristic algorithms lead to a better solution; the amount of improvement varied from algorithm to algorithm; (iii) among the five neighborhood solution generation operators, insertion operator was the best; (iv) among all algorithms tested, the hybrid differential evolution is the best, followed by tabu search in terms of average objective value.     

Reliability and validity of the Home Care STAT (Safety Task Assessment Tool)

Home care workers are a priority population for ergonomic assessment and intervention, but research on caregivers' exposures to hazards is limited. The current project evaluated the reliability and validity of an ergonomic self-assessment tool called Home Care STAT (Safety Task Assessment Tool). Participants (N = 23) completed a background survey followed by 10–14 days of self-monitoring with the STAT. Results showed that the most frequent task was house cleaning, and that participants regularly performed dangerous manual client moving and transferring tasks. Researcher in-home observations of 14 workers (duration ≤2 h) demonstrated that workers' self-assessments were moderately reliable. Correlational and multi-level analyses of daily self-assessment data revealed that several task exposures were significantly related to daily fatigue and/or pain. Other associations have implications for Total Worker Health™; for example, daily stress was positively associated with both pain and consumption of high calorie snacks. Findings support the STAT as a reliable and potentially valid tool for measuring home care workers' exposures to physically demanding tasks.     

Physiological cost of energy-equivalent noise exposures with a rating level of 85 dB(A):: Hearing threshold shifts associated with energetically negligible continuous and impulse noise

In industry continuous or impulse noise does not occur exclusively; rather it is a combination of both. If low-level continuous noise or impulse noise (below 120 dB) is added to an already existing high-level continuous noise this often numerically causes no essential increase in the rating level. Yet, it cannot be expected that also aural strain of these exposures is always negligible. Therefore, in a cross-over test series, ten male subjects (Ss) were exposed to white noise of 94 dB(A) for 1 h (TS I), energy-equivalent to an 8 h-rating level L_Ard of 85 dB(A). In a second test series (TS II) the same exposure was combined with 900 energetically negligible 5-ms impulses with a noise level of 113 dB(A) which increased the rating level by only 0.4 dB. The noise exposure of TS I and TS II was followed by an idealized resting phase in a soundproof cabin. In a third test series (TS III) the continuous noise of 94 dB(A) / 1 h was followed by 3 h of white noise at 70 dB(A). Such an additional load increases the L_Ard by merely 0.1 dB to 85.1 dB(A). In all three test series, the noise-induced temporary threshold shift (TTS₂) and its restitution were measured. The continuous noise exposure of 94 dB(A) for 1 h was associated with a TTS₂ of around 20 dB which disappeared completely after about 2 h. The additional impulse noise caused a small increase in the TTS₂ and a prolongation of the restitution time. The maximum mean temporary threshold shift for the group increased only slightly (from 22.5 to 25.9 dB, which nevertheless can be statistically proven at a significance level of p 0.99). Yet, more importantly, the restitution time increased from 126 to 175 min, i. e. 3 h, which can be statistically proven at a significance level of p0.95. The TTS₂-values of TS III did not differ significantly from those resulting from TS I. That was expected as the conditions up to that point in time were identical. But due to the additional subsequent exposure, the mean restitution time increased considerably from 126 min up to 240 min (4 h). The mean total physiological cost represented by the integrated restitution temporary threshold shift (IRTTS) increased in TS II by approximately 40% and in TS III even by 140%.

Relevance to industry

The results of the study show that levels of noise which have no influence on the rating level which traditionally is calculated according to the energy-equivalence principle are often of great importance, as they can lead to considerably prolonged restitution times. Therefore, the purely energy-equivalent determination of the rating level of both impulse noise and low sound levels can lead to an underestimation of latent problems so that over time a reversible TTS can evolve into a permanent threshold shift. The results are also of importance for the acoustic design of break rooms for noise-exposed workers. There should be conditions that allow an undisturbed restitution of hearing.     

Branch-and-Bound-Based Local Search Heuristics for Train Timetabling on Single-Track Railway Network

The modified formulation and two branch-and-bound-based local search heuristic algorithms for train timetabling in single-track railway network in the planning application are proposed. The original local search heuristic is modified such that when a neighbor of a currently tested resolved conflict for improvement is evaluated, the depth-first search branch-and-bound algorithm is employed with two branching rules: least-lower-bound and least-delay-time. The detailed implementation of the proposed heuristic algorithms are described, including the neighborhood definitions of overtaking and crossing conflicts, the procedure to detect overtaking and crossing conflicts, and a recursive procedure for the depth-first search branch-and-bound algorithm. The proposed heuristic algorithms, the original heuristic, the equivalent manual solution method and the exact solution method are compared using a toy problem and four problems (26-train, 50-train, 76-train and 108-train) in the Thailand Southern line railway network, which consisted of 266 single-track segments, 15 double-track segments, 282 stations/sidings, and total distance of 1577 km. The proposed heuristic algorithm with the least-lower-bound branching rule outperforms the other heuristics in terms of the solution quality with up to 2.827 % improvement over the equivalent manual solution method and less than 8 % optimality gap. The proposed heuristic algorithms require longer time to terminate than the original heuristic. The proposed heuristic algorithm with the least-lower-bound branching rule converges faster than that with the least-delay-time branching rule in all test problems. Based on the empirical results, the proposed heuristic algorithms are solvable in polynomial time. Furthermore, the proposed heuristic algorithm with the least-lower-bound branching rule is enhanced by embedding a uniform sampling strategy, and it is found that the total CPU time can be saved by about 50 % with marginally worse solution quality.     

求解卸装一体化的车辆路径问题的混合启发式算法

提出一种结合蚁群系统(Ant Colony System,ACS)和变邻域下降搜索(Variable Neighborhood Descent,VND)的混合启发式算法ACS_VND,求解卸装一体化车辆路径问题.利用基于插入的ACS解构造方法产生多个弱可行解,再逐个转换成强可行解,并选择其中最好的作为VND的初始解.在VND过程中使用三种不同的邻域结构:插入、交换和2-opt依次对解进行迭代优化.对55个规模为22~199的benchmark算例的求解结果表明,算法ACS_VND能在较短时间内获得52个算例的已知最好解,并且更新了其中44个算例的已知最好解,求解性能优于现有算法.     

Empirical investigation of the benefits of partial Lamarckianism

Genetic algorithms (GAs) are very efficient at exploring the entire search space; however, they are relatively poor at finding the precise local optimal solution in the region in which the algorithm converges. Hybrid GAs are the combination of improvement procedures, which are good at finding local optima, and GAs. There are two basic strategies for using hybrid GAs. In the first, Lamarckian learning, the genetic representation is updated to match the solution found by the improvement procedure. In the second, Baldwinian learning, improvement procedures are used to change the fitness landscape, but the solution that is found is not encoded back into the genetic string. This paper examines the issue of using partial Lamarckianism (i.e., the updating of the genetic representation for only a percentage of the individuals), as compared to pure Lamarckian and pure Baldwinian learning in hybrid GAs. Multiple instances of five bounded nonlinear problems, the location-allocation problem, and the cell formation problem were used as test problems in an empirical investigation. Neither a pure Lamarckian nor a pure Baldwinian search strategy was found to consistently lead to quicker convergence of the GA to the best known solution for the series of test problems. Based on a minimax criterion (i.e., minimizing the worst case performance across all test problem instances), the 20% and 40% partial Lamarckianism search strategies yielded the best mixture of solution quality and computational efficiency.     

Firefly Algorithm for solving non-convex economic dispatch problems with valve loading effect

The growing costs of fuel and operation of power generating units warrant improvement of optimization methodologies for economic dispatch (ED) problems. The practical ED problems have non-convex objective functions with equality and inequality constraints that make it much harder to find the global optimum using any mathematical algorithms. Modern optimization algorithms are often meta-heuristic, and they are very promising in solving nonlinear programming problems. This paper presents a novel approach to determining the feasible optimal solution of the ED problems using the recently developed Firefly Algorithm (FA). Many nonlinear characteristics of power generators, and their operational constraints, such as generation limitations, prohibited operating zones, ramp rate limits, transmission loss, and nonlinear cost functions, were all contemplated for practical operation. To demonstrate the efficiency and applicability of the proposed method, we study four ED test systems having non-convex solution spaces and compared with some of the most recently published ED solution methods. The results of this study show that the proposed FA is able to find more economical loads than those determined by other methods. This algorithm is considered to be a promising alternative algorithm for solving the ED problems in practical power systems.     

Physiological costs of the hearing due to noise exposure,additional physical stress,and combined exposure to alcohol and cigarette smoke

In 2 studies, each with 5 test series, physiological costs of the hearing due to legally tolerable noise exposures of 94 dB (A) for 1 hr have been measured audiometrically. The temporary threshold shifts (TTS) and their restitution time, as well as cardiovascular responses in work‐related heart rate increases, of 10 and 8 subjects (Ss), respectively, could be shown to be modulated by additional physical stress and combined exposure to alcohol (Study 1) and cigarette smoke (Study 2). Moderate dynamic muscle work (50 W) administered via a bicycle ergometer either immediately after noise, or simultaneous to the noise exposure, significantly reduced restitution time as well as the integrated restitution temporary threshold shift (IRTTS). A physical stress to 100 W—which exceeded the endurance level when demanded simultaneously to the noise exposure—did not show any favorable effects. However, if the same physical stress succeeded the noise exposure, and when it was interrupted several times for the audiometric measurements, it also brought about significant accelerations of the restitution processes. Some reductions in physiological costs of the hearing were found due to an intervening alcohol consumption (blood alcohol concentration ～ 0.08%) prior to the noise exposure and a simultaneous physical load of 50 W. Smoking 10 cigarettes instead of the consumption of alcohol was associated with a reduced TTS, but a prolonged restitution time. IRTTS as total physiological costs of the most unfavorable combination of noise, simultaneous high physical workload, and preceding smoke exposure was increased. The results of the test series with cigarette smoke—probably due to the small group of just 8 Ss and the counteracting effects of the agents carbon monoxide (CO) and nicotine—were not statistically significant, but these exposures were associated with a substantial activation of the cardiovascular system. Significant heart rate increases are evidence that CO and nicotine must not be neglected as influential factors in the context of physiological costs that the organism, and especially the hearing, has to pay for noise exposures. © 2002 Wiley Periodicals, Inc.     

Variable neighborhood search for multi-objective resource allocation problems

The Resource Allocation Problem (RAP) is a classical problem in the field of operations management that has been broadly applied to real problems such as product allocation, project budgeting, resource distribution, and weapon-target assignment. In addition to focusing on a single objective, the RAP may seek to simultaneously optimize several expected but conflicting goals under conditions of resources scarcity. Thus, the single-objective RAP can be intuitively extended to become a Multi-Objective Resource Allocation Problem (MORAP) that also falls in the category of NP-Hard. Due to the complexity of the problem, metaheuristics have been proposed as a practical alternative in the selection of techniques for finding a solution. This study uses Variable Neighborhood Search (VNS) algorithms, one of the extensively used metaheuristic approaches, to solve the MORAP with two important but conflicting objectives—minimization of cost and maximization of efficiency. VNS searches the solution space by systematically changing the neighborhoods. Therefore, proper design of neighborhood structures, base solution selection strategy, and perturbation operators are used to help build a well-balanced set of non-dominated solutions. Two test instances from the literature are used to compare the performance of the competing algorithms including a hybrid genetic algorithm and an ant colony optimization algorithm. Moreover, two large instances are generated to further verify the performance of the proposed VNS algorithms. The approximated Pareto front obtained from the competing algorithms is compared with a reference Pareto front by the exhaustive search method. Three measures are considered to evaluate algorithm performance: D1_R, the Accuracy Ratio, and the number of non-dominated solutions. The results demonstrate the practicability and promise of VNS for solving multi-objective resource allocation problems.     

Single‐shot High Dynamic Range Imaging Using Coded Electronic Shutter

Typical high dynamic range (HDR) imaging approaches based on multiple images have difficulties in handling moving objects and camera shakes, suffering from the ghosting effect and the loss of sharpness in the output HDR image. While there exist a variety of solutions for resolving such limitations, most of the existing algorithms are susceptible to complex motions, saturation, and occlusions. In this paper, we propose an HDR imaging approach using the coded electronic shutter which can capture a scene with row‐wise varying exposures in a single image. Our approach enables a direct extension of the dynamic range of the captured image without using multiple images, by photometrically calibrating rows with different exposures. Due to the concurrent capture of multiple exposures, misalignments of moving objects are naturally avoided with significant reduction in the ghosting effect. To handle the issues with under‐/over‐exposure, noise, and blurs, we present a coherent HDR imaging process where the problems are resolved one by one at each step. Experimental results with real photographs, captured using a coded electronic shutter, demonstrate that our method produces a high quality HDR images without the ghosting and blur artifacts.     

An investigation on major physical hazard exposures and health effects of forestry vehicle operators performing wood logging processes

Forest vehicle operators are occupationally exposed to combined hazards such as noise, whole-body vibration(WBV), adverse microclimate, and carbon monoxide. Such combined exposures may not only increase the risk of accidents but they may also have some synergized effects on the developments of major occupational diseases of the workers, which have been among the major concerns of the occupational safety and health for the forestry sector in Romania. This study investigated the combined exposures through measuring and analyzing the equivalent acoustic level LAeq (dB(A)), whole-body vibration (A(8)-value), working microclimate, and carbon monoxide inside the worker's cabin in the breathable area. The vehicles considered in this study included skidding vehicles dedicated to wood exploitation (type I) and agricultural tractors modified for logging (type II). The cumulative distribution function of each types of exposure was calculated in the analyses. This study found that the noise and WBV exposures had large probabilities of exceeding the permissible limits: for noise, 75% for vehicle type I, and 55% for vehicle type II; for the WBV, 63% for type I vehicles, and 72% for type II vehicles. The measured data suggest that the microclimate and carbon monoxide exposures were within their limits in the process of collecting wood. This study also found that 27% of workers participated in the study were detected with occupational diseases. Based on these findings, some intervention methods were recommended to control the exposures and health effects.