[Evaluation of thermal comfort in a student population: predictive value of an integrated index (Fanger's predicted mean value]

Practical applications and predictive values of a thermal comfort index (Fanger's PRV) were verified on a sample school population (1236 subjects) by studying the relationships between thermal sensations (subjective analysis), determined by means of an individual questionnaire, and the values of thermal comfort index (objective analysis) obtained by calculating the PMV index individually in the subjects under study. In homogeneous conditions of metabolic expenditure rate and thermal impedence from clothing, significant differences were found between the two kinds of analyses. At 22 degrees C mean radiant and operative temperature, the PMV values averaged 0 and the percentage of subjects who experienced thermal comfort did not exceed 60%. The high level of subjects who were dissatisfied with their environmental thermal conditions confirms the doubts regarding the use of the PMV index as a predictive indicator of thermal comfort, especially considering that the negative answers were not homogeneous nor attributable to the small thermal fluctuations (less than 0.5 degree C) measured in the classrooms.

[Evaluation of individual thermal load in working environments with non-homogeneous microclimatic conditions]

It is often very difficult to quantify the potential thermal stress of jobs requiring high worker mobility in unevenly hot environments. The determination of integrated indexes such as HSI can be a cause of error in risk evaluation. However, monitoring of physiological parameters of exposed workers, such as internal body temperature, provides a direct expression of man-environment interaction. On the basis of measurement of micro-climatic parameters and internal body temperature of subjects employed in a glass production plant, an attempt was made to calculate an integrated index of thermal stress risk which reflected the job requirements. The mathematical model used was the one proposed by Givoni and Goldman for prediction of rectal temperature and heart rate response to work in hot environments.

[Assessment of risk in occupational tasks with exposure to environmental noise of variable duration and intensity]

The discontinuous exposure to environmental working noise often brings about risk situations hardly assessable by means of phonometric measurements and studying the exposure time, even if accurate. The use of the personal dosimetry can simplify the measurements and give a time-weighted value (Leq) comparable to a fixed limit value. Such a measurement is effective only for the considered time (usually a work shift); nevertheless it is assumed to be representative of the usual exposure to the job even though the variability of the working conditions constitute a limiting factor. In this work we tried to verify the possible use of the measurements of environmental sound pressure levels given by the dosimeter every 0.25 sec. The first aim being the study of the type of distribution of these values (during 5 consecutive shifts) and the estimate of mean and standard deviation values. The mean and the standard deviation values were used to get a OTL (one sided tolerance limits) usually employed for assessing the working chemical pollution. The second aim being the compliance control and the possible need of more measurements.

[Importance of the relative humidity values in determining thermohygrometric comfort]

A condition of discomfort with specific symptoms, such as throat dryness, eye irritation, in a group of workers of a small, air conditioned, working department, is described. Neither the measurements of the possible environmental pollutants concentrations, nor the assessment of the usually adopted comfort indexes (PMV-PPD) justified the worker's symptoms. They completely disappeared by means of appropriate environmental improvements aiming to increase the relative humidity values from 29% to 50-55% (drop of the amount of the hygroscopic material stored, setting up of an humidifier). The effects of the low humidity values on the hygrometric and thermal comfort are finally discussed.

[Monitoring of occupational activities under the risk of heat stress: use of mathematical models in the prediction of physiological parameters]

Some authors proposed mathematical models that, starting from standardized conditions of environmental microclimate parameters, thermal impedance of the clothing, and energetic expenditure allowed the forecast of the body temperature and heart rate variations in respect to the basal values in subjects standing in the same environment. In the present work we verify the usefulness of these models applied to the working tasks characterized by standardized job made under unfavourable thermal conditions. In subject working in an electric power station the values of the body temperature and heart rate are registered and compared with the values obtained by the application of the studied models. The results are discussed in view of the practical use.

[Prospects for environment intervention following biological monitoring of exposure to chromium]

The authors study the statistical distribution and the graphical representation of the urinary chromium values investigated during three consecutive years in three work environments of a same plant: polishing 1 degree, electrotyping, polishing 2 degrees, to evaluate the environmental situations of exposure and their variations. The adopted method, based on the graphical representation of the values in logarithmic coordinate paper, allows to quickly and carefully calculate the percent of the workers having urinary chromium values above the prefixed limits.

[Validity of a biophysical model for predicting heart rate values during activities operating under a risk of thermal stress]

After measuring the heart rate values of workers unfolding a standardized job made under unfavourable microclimatic conditions, the Authors calculate them by application of a proposed biophysical model starting from ambient climatic conditions, energetic expenditure and thermal resistance of the clothing. The results, compared by means of statistical methods, do not show any significant difference between the two methods. Therefore is also possible the proposal of the use of the biophysical model for the prevision of heart rate under standardized working conditions.

[Reference values of chromium urine in the population residing in Lombardy]

The accurate determination of Cr in normal human urine still presents a considerable challenge, connected to its very low content, supposedly about 1 ppb. The analytical data obtaining from many Authors varying between 0.3 microgram/day and 150 micrograms/day. The question now arises which data picture the true Cr content of normal human urine. To this purpose we have determined the content of total urinary chromium in 310 healthy individuals (170 male, 140 female) resident in Lombardy (Italy). A mean urinary Cr concentration of 0.59 +/- 0.26 ppb was obtained. The levels of urinary chromium tended to be higher in males than in females and to decrease with age.

[Control of duration limits of work activity at risk in thermal stress by prediction of values for internal body temperature]

A biophysical model for studying the response of the rectal temperature to changes in metabolic rate and environmental conditions has been utilized to establish the safe exposure times for works at risk of thermal stress. The prediction of the rectal temperature allows to evaluate for how long the heat load due to metabolic rate is lasting after the work stopping in the period of recovery.

[Use of a biophysical model to verify various methods for limiting the time of work activity at risk in thermal stress]

The Authors measure the environmental microclimatic parameters (dry bulb temperature, wet bulb temperature, globe temperature, natural wet bulb, air speed, vapor pressure) in twenty working sites. Starting from the values obtained, they calculate the safe exposure times for works under unfavourable thermal conditions by means of three different methods (time weighted average WBGT, allowable exposure time-AET, required sweat rate index). Finally they verify the results obtained by application of a biophisical model proper to calculate the response of rectal temperature to changes in metabolic rate and environmental conditions.

[Decrease in environmental pollution and changes in biological indicators in occupational exposure to lead]

The Authors examine the variations of the levels of PbB and EPP in 39 workers at known lead exposure and evaluate the capacity of these parameters to follow the measured decreases of the environmental pollution. They conclude that the variations of the mean PbB values are well related to environmental pollution and that the diagram on the probability paper of median values and their corresponding standard deviations allows to calculate the number of exposed workers with biological values above a fixed limit.

Hepatic function in subjects exposed to environmental concentrations of DMF lower than the actually proposed TLV

Hepatic function investigation in 54 workers, exposed to an airborne concentration of DMF lower than TLV in an acrylic fiber plant, has been carried out. The results suggest the probable absence of hepatic cytolysis phenomena for this degree of exposure.

[Changes in spontaneous platelet aggregation induced by the ambient temperature]

The diagnostic meaning of the functional platelets modifications (particularly those of spontaneous platelet aggregation = P.A.) in cardiovascular pathology has been recalled. It is emphasized that, in order to have significantly predictable data on eventual pathological alterations in case of deviations of values considered normal, one has to use methods that do not differ from the real haemorheological conditions. A research has therefore been made with the purpose to evaluate the influence that variations of temperature may have on the samples collected and left to sediment (for the separation of the PRP) and the subsequent modifications of P.A. The research has been made in double on plasma sedimented at 37 degrees C and at room-temperature on 731 subjects, 289 of which were the casuistic groups for the subsequent statistic elaboration. With similar modalities in other 8 patients the eventual variations in excretion of beta-TG were looked for. The results have shown that there are important variations of the spontaneous P.A. rates, that the difference is always statistically very significant and that lowering the temperature of the samples favors an increase in beta-TG excretion . The Authors think therefore that only the sedimentation at 37 degrees C issues a plasma usefull for the further performing of platelets tests, while in the plasma obtained with sedimentation at room-temperature the platelets are perhaps already stimulated to an activation (and subsequently an aggregation) higher than the real one. Data obtained from a homogeneous group of subjects, healthy from a clinical point of view, allowed to fix the new range of normal values within 3% of aggregability . The mechanisms that lead to such different results are discussed. Emphasis is put on the fact that the spontaneous P.A. determined by the means mentioned seems satisfactorily near to the real clinical conditions. That's why the hypothesis arises that also other tests concerning platelet functions could be negatively influenced if they have room-temperature as a condition for plasma separation.

[Control of cardiac frequency in work activity at risk of thermal stress]

The working time in work places termically uncomfortable must be limited in order to prevent the risk of thermal stress; the safe exposure times are based on the microclimatic parameters and the energetic expenditure required for the job. Hearth rate measure is proposed by various Authors as index connected with the energetic expenditure level and with the microclimatic conditions. In the present work the Authors realise the monitoring of a job uncomfortable for thermal conditions by means of the hearth rate measure of the workers. The results show the better accuracy of the purposed method in comparison with the application of the safe exposure times.

[Microclimatic indexes and limits of safe exposure in work activity at risk of thermal stress]

The working time in work places thermically uncomfortable must be limited in order to prevent the risk of thermal stress. In a previous study we have demonstrated that the best method for calculation of the safe exposure times is based on the required sweat rate index. In the present work we verified in different work places termically uncomfortable, grouped for equivalent values of WBGT index, the variability of the safe exposure times calculated by means of a method just now mentioned for various levels of energetic expenditure. The results point out the possibility of a mathematical relation between energetic expenditure, WBGT index and mean of safe exposure times.

[Thermal balance in workers of in greenhouses for the cultivation of tropical plants]

The Authors starting from the microclimatic parameters globe temperature (tg), dry bulb temperature (ts) forced wet bulb temperature (tu), natural wet bulb temperature (tun), speed of the air (v) observed every half an hour in greenhouses for tropical plants, evaluate the required sweating rate per hour during a specimen working shift for a known energetic expenditure. The sweating rate values calculated exceed by far the highest limits accepted for the workers perfectly acclimatized and impose the application of the working safe exposure times.

[Relation between thermal comfort indices and various values of thermal impedence for clothes]

The Authors show that there is some relationship between WBGT microclimatic index and PMV thermic comfort index. This relationship can be noticed at various levels of energetic expenditure and for three values of thermic impedance from clothes used in working places in the four seasons.

[Microclimate and duration of work tolerance in hothouse for cultivation of tropical plants]

The AA. starting from the environmental values carried out in a greenhouse for tropical plants investigate the possibility of prevent the risk of thermal stress at standardized energetic expenditures by means of the measurement of a few microclimatic parameters; they elaborate also a nomogram proper to calculate the safe exposure times for works under unfavourable thermal conditions.

[Duration limit of moderately heavy work activity in technically unfavorable environments]

The working time in work places thermically uncomfortable must be limited in order to prevent the risk of thermal stress. The Authors measure the environmental microclimatic parameters (dry bulb temperature, wet bulb temperature, globe temperature, natural wet bulb temperature, air speed, vapor pressure) in twenty working sites of a thermal power plant. Starting from the values obtained, they calculate the safe exposure times under unfavourable thermal conditions by means of four different methods (WBGT, time weighted average WBGT, allowable exposure time-AET, required sweat rate index). The results are critically analysed.

[Threshold of energy expenditure for maintenance of thermal comfort in working areas]

The Authors test the possibility of improving the microclimatic conditions of some working areas by assessing the threshold energetic expenditure (KCal/hour and KCal/min) in order to maintain the thermic well-being by means of a "thermic comfort" parameter, PMV. For this purpose, we measured PMV on the basis of tg, ts, V, tun, Pa and Clo in 15 working areas. Then, by an iterative mathematical process, we calculated the threshold value of energetic expenditure in accordance with the values of PMV which show conditions of thermic comfort, that is between + 0.5 and - 0.5. In all the working areas observed it is possible to perform works requiring energetic expenditures lower than 200 KCal/h in conditions of thermic comfort; in 50% of the situations we examined even works requiring higher energetic expenditures.

[Simplification of periodic audiometric tests in persons exposed to industrial noise. An operative proposal]

Today the pure tonal audiometric test is the most used in periodical screening of the "hypoacusis" hazard in exposed patients because of its easy performance. The high number of patients to be tested and the screening frequency suggested to simplify the annual checks by testing only some of the frequency to be tested is made on the basis of the first complete audiogram performed according to a scheduled scheme. Available screening data and testing on the field show that a consistent reduction in testing time is possible and that the complete exam is reliable.