Influence of short-term aerobic training and hydration status on tolerance during uncompensable heat stress

The purpose of the present study was to determine the separate and combined effects of a short-term aerobic training program and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40°C, 30% relative humidity). Males of moderate fitness [<50 ml · kg⁻¹ · min⁻¹ maximal O₂ consumption (V˙O_{2 max} )] were tested while euhydrated or hypohydrated by ≈2% of body weight through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after either a 2-week program of daily aerobic training (1 h treadmill exercise at 65% V˙O_{2 max} for 12 days; n = 8) or a control period (n = 7), which had no effect on any measured variable. The training increased V˙O_{2 max} by 6.5%, while heart rate (f _c) and the rectal temperature (T _re) rise decreased during exercise in a thermoneutral environment. In the heat, training resulted in a decreased skin temperature and increased sweat rate, but did not affect f _c, T _re or tolerance time (TT). In both training and control groups, hypohydration significantly increased T _re and f _c and decreased the TT. It was concluded that the short-term aerobic training program had no benefit on exercise-heat tolerance in this uncompensable heat stress environment. Accepted: 12 November 1997     

Effects of wearing two different types of clothing on body temperatures during and after exercise

The experiment was conducted to investigate the human thermoregulatory responses during rest, exercise and recovery atT _a 20°C and 60% R.H. under the conditions of wearing two different types of clothing. Six healthy men wore two types of clothing: one covering the whole body area except the head (Type A, weight 1656 g), and the other covering only the trunk, upper arms and thighs (Type B, weight 996 g). The level of rectal temperature was kept significantly higher in Type B than in Type A during rest and recovery. The increased and decreased rates of rectal temperature during exercise and recovery were significantly greater in Type A than in Type B, respectively. These findings are discussed from the viewpoint of the differences of skin temperatures of the extremities between Type A and Type B.     

Diurnal variations of heart rate,urine flow and catecholamine excretion in subjects wearing clothing that provides different thermal insulation

This study investigated the effects of clothing providing different Clo values upon the circadian rhythm of sympathetic nervous activity, as inferred from urinary catecholamine excretion and heart rate, in a thermoneutral environment. Seven health female subjects were studied for 37.5 h, from 21:00 h on the first day to 10:30 h on the third day, in an isolated climatic chamber controlled at 23.8?±?0.2 °C and 60?±?5% RH. Light intensity was 500 lux from 06:30 to 19:30 h, 100 lux from 19:30 to 22:30 h and 0 lux from 22:30 to 06:30 h. Subjects were tested while wearing two different types of clothing: Type L, offering 1.048 Clo of thermal insulation and with the subjects’ extremities covered; and Type H, 0.744 Clo of thermal insulation and the subjects’ extremities exposed. Urine samples were collected every 4 h, their volumes were measured and they were later assayed for their contents of adrenaline and noradrenaline; the mean heart rate for each of these 4-h periods was also calculated. The daily profiles of the variables were assessed by ANOVA, which indicated that the amplitudes and phases of the daily rhythms differed between the clothing types. This result was examined in more detail by assessing the profiles by single and group cosinor analysis (period = 24 h). All four physiological variables showed clear and statistically significant group cosinor rhythms with both types of clothing. The mean amplitudes of urine flow, the excretion rate of urinary adrenaline and heart rate were greater when wearing Type H rather than Type L clothing (p = 0.01 for urine flow and heart rate; p = 0.072 for rate of excretion of adrenaline). Also, the acrophase of the rate of urinary adrenaline excretion was earlier in all subjects wearing Type H rather than Type L clothing (p = 0.048), and the acrophases of urine flow and urinary noradrenaline excretion rate were earlier in six and five of the subjects, respectively. These results show that clothing which is worn in an environment of moderate temperature (23.8 °C) and which offers a lower Clo value (especially if the distal extremities are exposed) might induce an increase in amplitude and/or an advance of acrophase in circadian rhythms of urine flow, excretion of urinary catecholamines and heart rate. It is suggested that these rhythmic changes, which imply changes in the daily profile of sympathetic nervous system activity, might be important when daily thermoregulation and comfort in response to the type of clothing being worn in daily life are considered.     

Special work-wear and protective clothing for Indian furnace workers

1. 1. In the present study two new, ergonomically designed, low-cost prototypes of protective work-wear for furnace workers of five hot metal and three glass factories in West Bengal were developed and evaluated on the basis of objective and subjective assessments.

2. 2. The objective assessments included the thermal data of the workplaces during summer and winter months, data on accidents and workers' physiological responses such as pulse rates, core and skin temperatures and sweat loss during work with the existing as well as work-wear. The subjective assessments were from questionnaires on the merits and demerits of the existing and new work-wear and the comfort votes.

3. 3. The study recommended the use of ergonomically designed, low-cost, washable, ventilated, vapour permeable, flame-retardant, radiant-heat-reflecting type special work clothing (Prototype No.II) by the workers to reduce the heat stress, accident risks and the physiological costs and to increase efficiency and productivity.

Comparison of thermal responses with and without cold protective clothing in a warm environment after severe cold exposures

1. 1. Ten male students remained in a severely cold room (-25°C) for 20 min. thereafter, they transferred in a warm room (25°C) for 20 min.

2. 2. This pattern was repeated three times, total cold exposure time amounting to 60 min.

3. 3. In the warm room, the subjects removed their cold-protective jackets, or wore them continously.

4. 4. Rectal temperature, skin temperatures, manual performance and thermal comfort were measured during the experiment.

5. 5. Removing cold-protective jackets after severe cold exposure increased peripheral skin temperatures and reduced the discomfort in the warm room.

6. 6. However, these results were accompanied by a greater decrease in rectal temperature and manual performance.

7. 7. It is recommended that workers continue to wear cold-protective clothing in the warm areas outside of the cold storage to prevent decreases in deep body temperature and work efficiency caused by repated cold exposures.

Effects of Two Types of Clothing on the Day-Night Variation of Core Temperature and Salivary Immunoglobulin a

Circadian variations in core temperature, skin temperatures, heart rate, and salivary immunoglobulin A (IgA) were compared in subjects wearing two different types of clothing that covered, or left uncovered, their extremities. The experiments were carried out on six female subjects at an ambient temperature of 24 ± 0.5°C and relative humidity of 50 ± 5%. One type of clotiiing consisted of long-sleeved shirts, full-length trousers, and socks (Type L: 1042 g, 1.048 clo); the other was half-sleeved shirts and knee-length trousers (Type H: 747 g, 0.744 clo). The main results were as follows: (i) The level of rectal temperature during night sleep was significantly lower with Type H than Type L clothing, and cosinor analysis indicated a significantly higher circadian amplitude with Type H clothing, (ii) Skin temperatures in the lower extremities increased significantly more on retiring to sleep with Type H than Type L clothing, (iii) Heart rate was significantly lower with Type H than Type L clothing during the sleep period, (iv) The day-night variation of salivary IgA showed a pattern that was the inverse of that of rectal temperature (i.e., low in the daytime and high in the nighttime), and the concentration of salivary IgA was significantly higher with Type H than Type L clothing at 02:30. (v) Subjectively, the self-assessed sleep quality was better with Type H clothing. These results suggest that clothing that leaves the extremities uncovered might be regarded as favorable at the moderate temperature since it induces good sleep and activates the immune response. (Chronobiology International, 14(6), 607–617, 1997)     

The Introduction of Postconsumer Recycled Material into TYVEK® Production, Marketing, and Organizational Challenges

In the late 1980s, with the advent of increased consumer environmental awareness, DuPont faced a challenge with its TYVEK® family of nonwoven polyethylene textile products. TYVEK is used in a wide variety of applications ranging from house wrap to medical packaging. One of the most visible portions of the business is envelopes used by FedEx (previously known as Federal Express), the wellknown courier and delivery service and by the U.S. Postal Service. As early as 1988, end users began asking questions about the environmental characteristics of TYVEK envelopes. As these questions increased, DuPont began to address the concerns directly. In response to the market's concern and because of the increased availability of postconsumer-recycled (PCR) polyethylene, DuPont decided to put PCR polyethylene into TYVEK, beginning with the envelope business. Further, DuPont developed a recycling infrastructure for TYVEK because, although TYVEK consists entirely of high-density polyethylene, which is highly recyclable, no infrastructure was in place to recycle the material. These decisions produced a wide variety of technical and organizational challenges the firm had to overcome. This case study examines how DuPont made these choices and overcame the difficulties created by implementing needed changes. Whereas the envelope market for TYVEK embraced PCR polyethylene, other product markets resisted the innovation. The article closes with a discussion of the lessons learned from DuPont's experience.     

Basic considerations in assessing and preventing occupational infections in personnel working with nonhuman primates

Transmission of zoonotic infections of nonhuman primates to human contacts is a documented occupational hazard. Although the list of naturally occurring and experimentally induced infections of nonhuman primates is extensive the risks of transmission may substantially be reduced by the use of good animal care practices, appropriate protective measures and devices, and suitable animal facilities. The essential elements of good animal care practices include high levels of personal hygiene; minimizing the creation of potentially infectious aerosols and droplets; use of personal protective clothing, devices, and vaccines; a system for reporting, evaluating, and treatment of occupational exposures and infections; and animal facilities appropriate for the species being used and the activities conducted. These essential elements are described and discussed in the context of published voluntary codes of practice--notably "Biosafety in Microbiological and Biomedical Laboratories."     

Antimicrobial and chemical detoxifying functions of cotton fabrics containing different benzophenone derivatives

Several benzophenone chromophoric groups were incorporated onto cotton fabrics by using 4-hydroxybenzophenone, 4,4′-dihydroxybenzophenone, 4-chloro-4′-hydroxybenzophenone, and 4-benzoylbenzoic acid as reagents. The fabric treatment was conducted by a pad-dry-cure method, and the benzophenone chromophoric group incorporated cotton fabrics were characterized and confirmed by FTIR. Tensile strengths of benzophenone chromophoric groups modified cotton fabrics were also measured. 4-Hydroxybenzophenone treated cotton fabric showed the most powerful antibacterial activity among all samples, and 4-benzoylbenzoic acid treated cotton fabric demonstrated pesticide degradation ability, under UV irradiation.     

Thermal resistance units

A proposal is made for standardization of the constant of proportionality used to derive thermal resistances in units of seconds per metre. The choice of a standard value equal to the volumetric specific heat of air at STP would reduce ambiguity in current publications and offer a rational conversion for the clo unit of insulation, as 1 clo = 200 sm^?1 (2 s cm^?1), which gives an alternative easily visualised reference for clothing insulation.