[The evaluation of the individual thermal load in work activity with uneven energy expenditure].

It is often very difficult to quantify the potential thermal stress in jobs characterized by sudden variations of energy expenditure and thermal overload for time periods of short duration. Heart rate varies rapidly with the changes of energy expenditure and thermal load and the application of the mathematical model, proposed by Givoni and Goldmann for prediction of heart rate response to work in hot environments, to values of the physiological parameter, continuously measured during the periods of work and rest, allows the calculation of the two components of the HSI stress index (Er, Emax) from which to derive safe times of exposure. In this study practical applications of the theoretical method are verified in the control of the potential thermal stress of workers engaged in the carbon coke production.

[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%.

[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.

[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.

[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).

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.