Although much is known about human body vibration discomfort, there is little research data on the effects of vibration on vehicle occupant drowsiness. A laboratory experimental setup has been developed. Vibration was applied to the volunteers sitting on the vehicle seat mounted on the vibration platform. Seated volunteers were exposed to a Gaussian random vibration, with 1-15 Hz frequency bandwidth at 0.2 ms(-2) r.m.s., for 20-minutes. Two drowsiness measurement methods were used, Psychomotor Vigilance Test (PVT) and Karolinska Sleepiness Scale (KSS). Significant changes in PVT (p0.4) was observed between objective measurement (PVT) and subjective measurement (KSS). The results suggest that exposure to vibration even for 20-minutes can cause significant drowsiness impairing psychomotor performance. This finding has important implications for road safety.

Researches into the relationship between the physical quantity of vibration and the subjectively perceived quantity become important in designs for the vibration environment. Subjective experimental methods to obtain the relationship between the physical quantity of vibration and the subjectively perceived quantity are different depending on the design objectives which consider the human sense of vibration characteristic. In this review, the following are outlined: (i) fundamental methods for obtaining the design objectives for vibration environments; (ii) reported findings on the physical quantity of vibration environments and the human characteristics of sense vibration; and (iii) problems with and limits of the ISO 2631-1 standard, which defines the subjective response of the ride comfort in public transportation. Finally, the directions of research into the subjective experimental methods for obtaining design objectives in the vibration environment considering of the human characteristics of sense vibration are described.

The effects of vitamin D on the musculoskeletal system are well established. Its deficiency causes osteomalacia, secondary hyperparathyroidism, and an increased risk for fractures and falls. However, clinical and experimental evidence points to extra-skeletal actions of vitamin D, including on immune and respiratory systems.Thus, during this COVID-19 pandemic, a possible deleterious role of vitamin D deficiency has been questioned.This paper aims to present a brief review of the literature and discuss, based on evidence, the role of vitamin D in the lung function and in the prevention of respiratory infections. Relevant articles were searched in the databases MEDLINE/PubMed and SciELO/LILACS. The mechanisms of vitamin D action in the immune system response will be discussed. Clinical data from systematic reviews and meta-analyses show benefits in the prevention of respiratory infections and improvement of pulmonary function when vitamin D-deficient patients are supplemented. At the time of writing this paper, no published data on vitamin D supplementation for patients with COVID-19 have been found. Vitamin D supplementation is recommended during this period of social isolation to avoid any deficiency, especially in the context of bone outcomes, aiming to achieve normal values of 25(OH)D. The prevention of respiratory infections and improvement of pulmonary function are additional benefits observed when vitamin D deficiency is treated. Thus far, any protective effect of vitamin D specifically against severe COVID-19 remains unclear. We also emphasize avoiding bolus or extremely high doses of vitamin D, which can increase the risk of intoxication without evidence of benefits.

This study aims to investigate the effects of whole-body vibration (WBV) exposure on the disturbance of standing balance function assuming that the cause of slip, trip and fall accidents in the land transportation industry is related to WBV exposure when traveling in vehicles. In the experiment, ten participants underwent 60 min of virtual driving in a driving simulator (DS) for WBV exposure. In addition, standing balance measurements were conducted before exposure, immediately after exposure, 2 min after exposure and 4 min after exposure. Four conditions were considered by combining two magnitudes of WBV exposure and the driver and passenger conditions. This study focused on two indexes of standing balance, namely, total length and enveloped area and the rate of change relative to the value before the vibration exposure was calculated. The rate of change remained almost constant at 1.0 in the control condition without vibration exposure, whereas that under vibration exposure conditions varied. Interestingly, the rate of change at 2 min after exposure remained high in the driver condition, but it decreased to almost 1.0 in the passenger condition. Since no difference appeared in the vibration acceleration measured at the seating surface between the driver and passenger conditions, it was believed that the difference between the driving and passenger conditions was related to fatigue caused by the accelerator-pedal operation. As a result of considering the percentage of the standing balance that returned to 1.0 after 4 min in most conditions, this study proposed that a rest period of several minutes be allowed from the experiment in which the participants were exposed to vibration at $0.5\mathrm{m}/{\mathrm{s}}^2$ rms for 60 min at the DS. Further basic experiments will be conducted to introduce another WBV exposure assessment, including loss of standing balance as a health indicator, to ISO 2631-1.

The present study involved performing an experiment to clarify whether vibration measurement values on the tool handle, in accordance with ISO 5349-1, can assess risk from workplace environments. The study investigated the relationship between the vibration magnitude of a hand-held electric drill with different operating postures. The experiment included the determination of the participant’s temporary threshold shift (TTS) of vibrotactile perception threshold (VPT) at the tip of the index finger. The experimental hypothesis was that the vibration measurement values on the tool handle, in accordance with the ISO 5349-1 standard, include the effect of posture on the vibration measurements obtained despite the variation in posture and test participants. The hand-transmitted vibration (HTV) was applied using a hand-held electric drill applied to a pre-cast concrete paving slab substrate (600 × 600 × 50 mm, 55 MPa) using a 10 mm diameter masonry drill bit (without hammer action). The tool was operated using the right hand on twelve male subjects with three working postures (n = 36). Vibration was measured in three orthogonal directions according to the international standard ISO 5349-1 procedure. Vibration magnitudes were expressed as root-mean-square (r.m.s.) acceleration, frequency-weighted using the $W_h$ frequency weighting. Clause 4.3 states that the characterisation of the vibration exposure is assessed from the acceleration of the surface in contact with the hand as the primary quantity. The experimental results indicate that the TTS following vibration exposure is not related to the measured vibration magnitude on the tool handle. Therefore, the automatic inclusion of posture and test participant variation is not proven. The results suggest that the vibration measurement values on the tool handle do not predict the TTS after hand-transmitted vibration in varying posture across the test participants. The research concludes that tool handle vibration measurement, in accordance with ISO 5349-1, does not properly assess the potential hazard from authentic workplace tool usage conditions of varying postures.