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Green tobacco sickness is an occupational illness of tobacco illness of tobacco harvesters that is thought to be caused by dermal absorption of nicotine from contact with green tobacco leaf. Wearing of rubberized nylon rainsuits effectively prevented nicotine absorption in volunteers who picked wet tobacco. Nicotine absorption was demonstrated in workers who wore clothing that was not waterproof.
This study used partitional calorimetry to determine the influence of fluid replacement on heat storage during uncompensable heat stress. Eight males performed either light (L; level treadmill walking at 0.97 m x s(-1) (3.5 km x h(-1)) or heavy (H; 1.33 m x s(-1) (4.8 km x h(-1)) at a 4% grade) exercise at 40 degrees C and 30% relative humidity while wearing nuclear, biological and chemical (NBC) protective clothing. Subjects received either no fluid (NF), or 200 or 250 ml of fluid (F) as warm water at approximately 35 degrees C immediately before and every 15 min during the L and H trials respectively. Similar reductions in heart rate were observed at both metabolic rates with F but rectal temperature responses were not different between F and NF. Tolerance time was extended during L/F (106.5 +/- 22.1 min) compared with L/NF (93.1 +/- 20.8 min) but fluid replacement had no influence during H (59.8 +/- 9.5 min and 58.3 +/- 11.1 min for F and NF respectively). Fluid replacement also had no effect on the rate of heat storage during L (108.2 +/- 20.6 W x m(-2) and 111.0 +/- 22.6 W x m(-2) for F and NF respectively) and H (172.5 +/- 11.5 W x m(-2) and 182.1 +/- 15.8 W x m(-2) for F and NF respectively). However, heat storage expressed per unit of mass was significantly increased during L/F (18.5 +/- 4.0 kJ x kg(-1) ) compared with the other trials (16.3 +/- 4.8 kJ x kg(-1), 16.6 +/- 3.0 kJ x kg(-1) and 16.7 +/- 4.0 kJ x kg(-1) for L/NF, H/F and H/NF respectively). It was concluded that fluid replacement does not alter the rate of heat storage during uncompensable heat stress but does increase the heat storage capacity during light exercise when tolerance times are > 60 min.
Protective clothing (PC) results in a micro-environment between itself and the body. Workers are then exposed to a heat stress greater than the ambient environment alone, which is a reflection of micro-environment, metabolic rate and time. Adjustments to the ambient environment to account for the micro-environment have been formulated as a means to predict heat strain for safety and productivity purposes. Measurement of the actual micro-environment was made for a mean of 63.1 +/- 7.9 min using a remote sensor at the shoulder, hip and thigh levels on 15 subjects during a continuous work protocol (300 kcal/h) in impermeable PC at an ambient temperature of 30.1 degrees C wet bulb globe temperature (WBGT) (32 degrees C dry, 29 degrees C wet, 33 degrees C globe). Micro-environment temperature increased over the duration of the work period. There was no statistically significant difference (p>0.05) between the measurements made at the three different body sites for temperature or humidity. The mean micro-environmental WBGT at the end of work was 34.6 degrees C WBGT. Micro-environment WBGT increased rapidly in the first 20 min of work then slowed, rising only 0.5 degrees C WBGT from 40 to 60 min. These results suggest that at this particular high ambient temperature (30.1 degrees C WBGT) an adjustment factor of 5 degrees C WBGT would give a more accurate indication of thermal stress for up to 1 h of continuous moderate work within PC. For shorter work durations, an even smaller adjustment would be appropriate.
To examine the effects of firefighting personal protective ensemble (PPE) and self-contained breathing apparatus (SCBA) on exercise performance, 12 males completed two randomly ordered, graded exercise treadmill tests (GXTPPE and GXTPT). Maximal oxygen consumption (VO2max) during GXTPPE was 17.3% lower than the GXTPT in regular exercise clothing (43.0 +/- 5.7 vs. 52.4 +/- 8.5 ml/kg per min, respectively). The lower VO2max during the PPE condition was significantly related (r = 0.81, p < 0.05) to attenuated peak ventilation (142.8 +/- 18.0 vs. 167.1 +/- 15.6 l/min), which was attributed to a significant reduction in tidal volume (2.6 +/- 10.4 vs. 3.2 +/- 0.4 l). Breathing frequency at peak exercise was unchanged (55 +/- 7 vs. 53 +/- 7 breaths/min). The results of this investigation demonstrate that PPE and the SCBA have a negative impact on VO2max. These factors must be considered when evaluating aerobic demands of fire suppression work and the fitness levels of firefighters.
Fire fighter breathing apparatus instructors (BAIs) must possess the ability to respond to both the extrinsic stress of a high temperature environment and the intrinsic stress from wearing personal protective equipment (PPE) and self-contained breathing apparatus (SCBA), repeatedly and regularly, whilst training recruits in live fire training exercises (LFTEs). There are few previous investigations on BAIs in hot environments such as LFTEs, since the main research focus has been on regular fire fighters undertaking exercises in temperate or fire conditions at a moderate to high exercise intensity. In this study, the intrinsic cardiovascular stress effects of wearing PPE + SCBA were first investigated using a step test whilst wearing gym kit (control), weighted gym kit (a rucksack weighted to the equivalent of PPE + SCBA) and full PPE + SCBA (weight plus the effects of protective clothing). The extrinsic effects of the very hot environment were investigated in BIAs in LFTEs compared to mock fire training exercises (MFTEs), where the fire was not ignited. There was an increase in heart rate due to the modest workload imposed on the BAIs through carrying out the MFTEs (25.0 (18.7)%) compared to resting. However, when exposed to fire during the LFTEs, heat storage appears to be significant as the heart rate increased by up to 39.8 (+/-20.1)% over that of the mock LFTEs at temperate conditions. Thus, being able to dissipate heat from the PPE is particularly important in reducing the cardiovascular responses for BAIs during LFTEs.
An experiment was carried out to measure the vapour resistance of two-layer clothing ensembles as a function of air permeability of the outer layer, open or closed apertures, wind, and walking, both for the total ensemble and for the outer garment alone. Six subjects walked on a treadmill (0.0, 2.5, and 5 km.h-1) which was placed in a wind tunnel (0.2, 0.7, and 3.0 m.s-1). They wore long underwear and an outer garment made of impermeable (imp), microporous (mpo), low air permeable (loa), or high air permeable (hia) fabric. Vapour resistances were determined by a trace gas method, calibrated against water vapour resistance. The vapour resistances of the underclothing and the outer garment were calculated from the measured data, as was the ventilation through the apertures. The vapour resistance of the underclothing was almost constant at 5 mm air equivalent. The ventilation was strongly dependent on wind and motion but still so low (54 l.min-1) that only the impermeable garment could benefit from it noticeably. The vapour resistance of the garments also varied strongly (imp 55-200 mm, mpo 12-20 mm, loa and hia 1-14 mm air equivalent). For the imp garment, this is due to leakage of air, whereas the vapour permeable garments were dominated by the diffusion and air penetration through the fabric. It is concluded that ventilation with vents cannot match the effect of vapour permeability, and that real low vapour resistances are only possible with air permeable fabrics.
Work in moderate or hotter environments while wearing encapsulating protective clothing (PC) results in heat storage and substantial diminution of work productivity, as well as being a potential health risk. An ability to predict the responses of workers using PC would be very useful. Predictions were made of work times at 21 degrees C of 15 subjects performing prolonged hard work (450 W gross) while wearing PC, based upon prior measures of short-duration bench stepping in PC and heart rate responses. A simple model was derived that shows good potential for predicting work time in moderate temperatures in PC; Total Time = 7.2 (bench step duration) - 34 (bench comfort) + 4 (height); R2 = 0.83, C.V. = 13. Unexpectedly, models that incorporated recovery heart rate as a variable were not as effective. With further refinement, the prediction approach tested in this study would be immediately useful for managing military and civilian personnel working in PC. Additionally, it could be utilized at minimal cost during routine training.
Six young, healthy male subjects performed a series of experiments in a climatic chamber in different environmental conditions wearing protective ventilated NBC clothing. Ambient temperature, TA, ranged from -20 to 35 degrees C, relative humidity, RH, from 20 to 85%, and air velocity, VA, from 0 center dot 1 to 5 center dot 0 ms-1. In addition, thermal radiation, measured by the temperature of the globothermometer, TG, was artificially increased in some experiments. A total of 32 experiments were performed. The subject had to exercise on a bicycle ergometer at a mechanical power of 60 W for 120 min. Heart rate, HR, oxygen uptake, VO2, skin temperature, Tsk, and rectal temperature, Tre, were measured during the experiments together with the temperature of the space between skin and garment, Tmu. Sweat loss was determined as the difference of the body weight before and after the experiment. Tmu was well correlated with the chamber environmental parameters. During heat exposure work duration began to decrease progressively from a Tmu > 30 degrees C, reducing to 40 min at the highest thermal load. About the same value of Tmu marked the departure of HR, VO2, Tsk and Tre from the values measured during the same work load in neutral conditions. Also, during cold exposure at -20 degrees C work duration was reduced below 1 h, but the limit appeared to be the cold at the extremities. From these findings it appears that Tmu is a good indicator of the thermal load and is related to the environmental condition by the equation: Tmu = 9 center dot 93 + 0 center dot 56 TA + 0 center dot 023 TG + 0 center dot 14 RH (T in degrees C, RH in %). For better comfort and performance Tmu should be monitored whenever a subject has to work wearing an NBC garment and the ventilating system must be adequate to fulfil the needs imposed on the subject by an adverse environment, in particular a high relative humidity.
The aim of the study was to obtain comprehensive anthropometric data from which to develop a sizing system appropriate for inclusion in specifications for protective clothing; and for purchases of other selected equipment. Fifty-five body dimensions on a male sample of the New Zealand Fire Services (n = 691, approximately 7% of employees) were obtained by direct measurement. Descriptive statistics and selected percentiles (5th, 50th, 95th) are given. The body dimensions accounting for most of the variance in the data were established by factor analysis and are reported here. Size groups for various body sections based on the relevant measurements of that section were established by cluster analysis around a control variable.
The aim of the study was to assess the use of 3M porous polymer extraction discs (3M Empore sorbent filters) for detection of chemical permeation of protective clothing. Analysis of some commonly used solvents on 3M Empore sorbent filters was performed for methanol, acetone, trichloroethylene (TriCE), and toluene by solvent desorption and gas chromatography. All solvents exhibited >98 percent adsorption on the filters at a spiking level of 1.8 microL for each solvent. Solvent recovery for the system was calculated for each solvent, ranging from 72-94 percent (RSD < or = 4.0%) for all solvents over the spiking range 0.2-1.8 microL. The modified ASTM F739 method was used to determine breakthrough times for five protective glove materials (polyvinyl chloride, natural rubber, polymerized alkene, nitrile, and nitrile butyl rubber) using the model solvents as test chemicals. Breakthrough times for each type of protective glove were determined, and found to range from 36 s to 9 min for acetone, from 142 s to 52 min for methanol, from 18 s to 12 min for TriCE, and from 32 s to 28 min for toluene. The quantitative mass of the solvents on the filters at the time of breakthrough detection ranged from 150-159, 157-166, 570-581, and 371-382 microg/cm2 for acetone, methanol, TriCE, and toluene, respectively. The sorbent filter should find utility in collecting chemical permeation samples through protective gloves in both laboratory and field studies for quantitative analysis.
The permeability coefficient of benzene vapor in air was calculated from experimentally measured values of solubility coefficient and diffusion coefficient for natural rubber, nitrile, neoprene, natural rubber plus neoprene, butyl rubber, polyvinyl chloride and polyethylene membranes. The permeability coefficient for natural rubber at room temperature (approximately 23 degrees C) was 4.2 x 10(-10) cm2/sec when the concentration of benzene in air was 10 ppm. This means that a worker (1.8 m2 surface area) completely clothed in a 0.0254 cm (10 mil) natural rubber suit would be exposed via the skin to 0.3 microgram benzene in an 8-hour shift if the benzene concentration were 10 ppm. In the same time period and with the same benzene concentration the worker would inhale 1600 microgram benzene if his tidal volume were 700 cm3, his breathing rate were 15 min-1, and he was wearing a respiratory with a protection factor of 100. Permeability coefficients for other vapor-membrane systems available in the literature suggest that exposure to vapors penetrating protective garments are in general negligible when compared with inhalation exposures for low vapor concentrations.
A simplified apparatus and procedure for determining the permeation rate of volatile chemical through protective clothing was developed. The method is applicable to all types of sheet material and provides an accurate measurement of the permeation rates as a function of time. The breakthrough times and permeation rates of 1,4-dichloro-2-butene for fifteen commercially available materials were determined.
Chemical permeation of acetone through unsupported Neoprene using the ASTM cell and another commercially-available, but smaller, test cell was compared. Also, different portable direct-reading instruments were used to determine breakthrough time and steady-state permeation. The breakthrough times between the two permeation cells and among different portable direct-reading instruments were not statistically different. However, steady-state permeation rates between the two cells using the same direct-reading instrument were statistically different. Chemical permeation test methods suitable for field evaluation of chemical protective clothing are discussed.
Polychlorinated biphenyls (PCBs) have been used in a number of applications, particularly in the electric power industry. While these materials are no longer manufactured in the United States, they still exist in the field. Because of the hazardous nature of these compounds, effective chemical protective clothing is required. The permeation of neat PCBs, and solutions with trichlorobenzene and paraffin oil, through 11 different protective garment materials was determined. These experiments were done both with a permeation cell with water collection medium, and by periodically swiping thumb cots which contained the challenge liquids. Contamination was a continuing problem because of the resinous, nonvolatile properties of PCBs. While the results from the two methods were not identical, they did agree qualitatively. The best protection against PCBs was provided by nitrile, Viton, Viton SF and Vitrile. While the results with PVA and Teflon were also very good, these materials have other characteristics which may make their use suspect. For most of the other materials, the performance depended on the challenge liquid. The weight and volume changes which occurred when the materials were soaked in the challenge liquids were determined. The volume changes of 80 percent of those challenge/material combinations which exhibited breakthrough correlated with the breakthrough times normalized to the square of the material thickness.
The permeation of methylene chloride and perchloroethylene through seven protective clothing materials was studied to determine the permeation parameters, and to investigate the effect of solubility (polymer weight gain) and material thickness on the permeation parameters. The materials tested were two different nitrile rubbers, neoprene, Combination (a blend of natural rubber, neoprene and nitrile), two different polyvinyl chlorides, and polyvinyl alcohol. Methylene chloride permeated through all materials, except PVA, with breakthrough times in the range of 2 to 8 min, and permeation rates in the range of 1250-5800 micrograms/cm2 X min. PVA and unsupported nitrile offered good protection against perchloroethylene with breakthrough time occurring after 2 hr. Perchloroethylene permeated through the other materials with breakthrough times in the range of 8 to 36 min and permeation rates in the range of 200 to 1600 micrograms/cm2 X min. It was shown that for both chemicals, there is a correlation between the solubility (weight gain) and the ratio of permeation rate to breakthrough time (PR/BT). For all material/chemical pairs, an increase in solubility, increased (PR/BT). The change in material thickness had an effect on breakthrough time and permeation rate, but no effect on normalized breakthrough time. An increase in thickness reduced permeation rate and increased breakthrough time.
A "round-robin" interlaboratory study was conducted to validate the relative precision of the American Society for Testing and Materials (ASTM) F-903 test method for measuring the resistance of protective materials to penetration by liquids. The study utilized seven independent laboratories performing three trials of five protective clothing materials challenged by five widely used commercial liquids. The level of overall agreement for interlaboratory results suggests a relatively high confidence in the precision of the method. Systematic errors, however, may reduce the confidence of this method for certain materials and solvents. Recommendations to eliminate or reduce variability due to systematic errors include reduction of test pressure, use of a support screen, reporting of permeation evidence as a failure, and the use of a fluorescent dye to enhance visibility.
An automated permeation test system was developed to collect permeation data. Three test specimens were evaluated simultaneously versus a challenge gas. The study evaluated chemical protective clothing garment materials for use by emergency response personnel confronted by ammonia or ethylene oxide in the gas phase. A total of 13 encapsulating suit materials and 2 glove materials were tested. Surgical latex material is not recommended for use in handling ammonia or ethylene oxide; other materials offer much greater protection.
Although the polymer literature contains many references to the effects of temperature on diffusion coefficients of gases and vapors, little attention has been paid to the effect of temperature on permeation of liquids in either the polymer or industrial hygiene literature. Nevertheless, it is an important problem in the selection and use of chemical protective clothing (CPC) because most permeation tests are conducted at 20-25 degrees C, but actual polymer/solvent systems are often at higher temperatures in field use. A simple relationship between temperature and permeation rate does not exist; this may be the reason that little effort has been made at factoring temperature into CPC selection and use. In this study, five polymer/solvent systems were tested at 25, 37, and 50 degrees C. An Arrhenius relationship was used to relate temperature and permeation for these and 11 other data sets from the literature. Constants from the Arrhenius equations were calculated with excellent correlation and were used to construct equations for estimating temperature effects. With knowledge of steady-state permeation rate or breakthrough detection time at 25 degrees C and thickness for any polymer/solvent combination, the equations allow one to predict a new permeation rate or breakthrough detection time at any other temperature within a range of approximately 25-65 degrees C.