湿热环境中军人劳动耐受时限的研究

目的 探索湿热环境下劳动战士的安全保障措施。方法 通过环境热强度（湿黑球温度等）与人体热紧张指标（肛温、心率与出汗率）的关系,规定不同热强率与不同劳动强度下为保障战士安全的时限。结果 湿热环境劳动的时间限值划分为生理安全上限与耐胺极限两种。生理安全上限时间：湿黑球温度（ＷＧＴ）３２℃时中度劳动（ＭＷ）〈３ｈ、重度劳动（ＨＷ）１ｈ、停止极重度劳动（ＥＨＷ）;ＷＧＴ３１℃时ＭＷ３ｈ、ＨＷ１．５～２ｈ、停止ＥＨＷ;ＷＧＴ３０℃时ＭＷ４ｈ、ＥＨＷ１ｈ、ＥＨＷ１ｈ;ＷＧＴ２９℃时ＭＷ不限制时间、ＨＷ４ｈ、ＥＨＷ１．５ｈ;ＷＧＴ２８℃时ＨＷ不限制时间、ＥＨＷ２～４ｈ;ＷＧＴ２７℃时ＭＷ４ｈ、ＨＷ３ｈ、ＥＨＷ１ｈ;ＷＧＴ３０℃时ＭＷ不限时间、ＨＷ４ｈ、ＥＨＷ２～３ｈ;ＷＧＴ２９℃时ＨＷ不限制时间、ＥＨＷ４ｈ;ＷＧＴ２８℃时Ｅ     

Laboratory evaluation of permissible exposure limits for men in hot environments

Forty-six industrial workers completed a total of 653 one-hour work bouts requiring an average of 122-235 kcal/M2/hr in an environmental chamber maintained at heat stress levels ranging from 8-37 degrees C wet bulb globe temperature (WBGT). Heart rates (HR) and rectal temperatures (Tre) were measured at the end of each work bout. Environmental heat stress levels were divided into two groups - those above and those below the permissible exposure limits (PEL). The PEL is the proposed maximum environmental thermal stress to which industrial workers can be exposed without endangering their health. The number of observations in each of these regions was further divided into those which were above the recommended limits of a World Health Organization study group (HR less than or equal to 110 bpm, Tre less than or equal to 38.0 degrees C) and those which were not. The number of "safe" (HR less than or equal to 110 bpm, Tre less than or equal to 38.0 degrees C) observations in environments with heat stress less than or equal to the PEL ranged from 100% to 2.4% depending on subject acclimatization and work rate. The degree of protection was always less in the winter than in the summer and was less for higher work rates. Men who normally worked in hot environments had fewer "excessive" HR's and Tre's than those who did not.     

Factors influencing endotoxin concentrations on cotton grown in hot, humid environments: a two year study

Cotton leaf, bract, fibre from opened bolls, and soil samples were collected weekly during two growing seasons (1984, 1985). Total and Gram negative bacterial populations were determined for each sample. Representative bacterial isolates were identified and endotoxin concentrations determined. For both years total and Gram negative bacterial populations on all sample types remained relatively stable until plant senescence. Afterwards, until plant death by frost, counts for all samples increased dramatically. Enterobacter agglomerans was the predominant species on leaf and bract, whereas the "all other" Gram negative bacterial species classification was the most common on fibre, with E agglomerans a close second. Senescence affected the occurrence of the species isolated. Statistical analysis partitioned by sample type showed strong correlations between endotoxin concentrations and certain bacteriological and environmental variables. The data suggest that in hot, humid environments the concentration of endotoxin on cotton leaf, bract, and fibre may be predicted by total and Gram negative bacterial counts, daily high temperature, and week after plant germination.     

Factors influencing endotoxin concentrations on cotton grown in hot, humid environments: a two year study.

Cotton leaf, bract, fibre from opened bolls, and soil samples were collected weekly during two growing seasons (1984, 1985). Total and Gram negative bacterial populations were determined for each sample. Representative bacterial isolates were identified and endotoxin concentrations determined. For both years total and Gram negative bacterial populations on all sample types remained relatively stable until plant senescence. Afterwards, until plant death by frost, counts for all samples increased dramatically. Enterobacter agglomerans was the predominant species on leaf and bract, whereas the "all other" Gram negative bacterial species classification was the most common on fibre, with E agglomerans a close second. Senescence affected the occurrence of the species isolated. Statistical analysis partitioned by sample type showed strong correlations between endotoxin concentrations and certain bacteriological and environmental variables. The data suggest that in hot, humid environments the concentration of endotoxin on cotton leaf, bract, and fibre may be predicted by total and Gram negative bacterial counts, daily high temperature, and week after plant germination.     

Protective clothing in hot environments

The high level of protection required by personal protective clothing (PPC) severely impedes heat exchange by sweat evaporation. As a result work associated with wearing PPC, particularly in hot environments, implies considerable physiological strain and may render workers exhausted in a short time. Recent development of algorithms for describing the heat transfer, accounting for pumping and wind effects, comprises improvement of the prediction of thermal stress. Realistic corrections can then be made to the available measures of thermal insulation and evaporative resistance of a given clothing ensemble. Currently this information is incorporated in international standards for assessment of thermal environments. Factors, such as directional radiation and wetting of layers, were studied in a recently completed EU research project. The development of advanced thermal manikins and measurement procedures should provide better measures for predictive models. As with all methods and models, the results need validation in realistic wear trials in order to prove their relevance and accuracy.     

Physiological responses of firefighters wearing level 3 chemical protective suits while working in controlled hot environments.

Firefighters in Queensland are exposed to hot, humid weather conditions that contribute to the overall workload encountered during emergency operations. Responding to certain hazardous material incidents requires firefighters to wear fully encapsulated chemical protective suits for a maximum period of 20 minutes. The nature of these suits, combined with workload and environmental conditions, poses a potential heat stress problem for firefighters. This study evaluates the heat-induced physiological responses of firefighters while wearing fully encapsulated chemical protective suits in a series of controlled thermal environments. Heart rate, body (aural) temperature, blood pressure, fluid loss, and a rating of perceived exertion were measured to evaluate the effect of increasing ambient air temperature during the performance of standard tasks. The results of the study indicated that the significant increase in heart rate, body temperature, and blood pressure was directly related to the increase in air temperature. The research indicates that the recommended suit wearing time of 20 minutes provided adequate physiological protection under the research conditions.     

Combined effects of toluene and hot microclimate on human body

It is shown in the paper that sensitivity of human organism to the toxic action of toluene is not changed under exposure to the microclimate, producing allowable thermal state, and is increased under exposure to the heating microclimate leading to the development of maximum thermal state. Under toluene exposure in the concentration 300 mg/m3 resistance to the heating microclimate under the conditions of joint exposure to these factors is reduced, which is manifest in an earlier onset of the maximum thermal state in people under observation.     

Dyslipidemia in industrial workers in hot environments

The aim of the study was to follow the rate and manifestation of dyslipidemia in industrial workers exposed to heat. One hundred and two male industrial workers exposed to heat and a control group of 102 male workers were studied. The microclimate components were followed and Wet Bulb Globe Temperature (WBGT) was calculated. The mean WGBT was 35.4 degrees C (28.4-41.7 degrees C) for the studied heat exposed work places. The lipid indices: total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triacylglycerols were assayed with enzymatic tests. TC/HDL-C ratio was calculated, too. Arterial pressure, anthropometric variables, smoking, alcohol use were followed and no significant differences between the studied groups were found. Significantly higher TC, LDL-C and TC/HDL-C were found with the heat exposed industrial workers. Odds ratio indicated higher risk in heat exposed industrial workers of becoming dyslipidemic [for TC OR = 1.481 (1.097-2.002) and for LDL-C OR = 1.539 (1,123-2.111)]. Regular screening of lipid profile in heat exposed workers is recommended.