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Biomedical subjects

M V Jokl

Publications and source records attributed to M V Jokl.

10 recordsLinked to original sources
PubMed1998

New units for indoor air quality: decicarbdiox and decitvoc.

Two new units are proposed for the evaluation of indoor air quality using the decibel concept, which give a much better approximation of the human perception of odour intensity, compared to the CO2 and total volatile organic compounds (TVOC) concentration scales: the decicarbdiox and the devitvoc. On the psychophysical scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to one, and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8%. It is equivalent to: (1) a CO2 threshold concentration of 485 ppm-0 dB (odour CO2)-0 dCd (decicarbdiox), and (2) a TVOC threshold concentration of 50 micrograms m-3-0 dB (odour TVOC)-0 dTv (decitvoc). The upper limit is determined by the initial value of toxicity: (1) CO2-15,000 ppm-134 dCd, and (2) TVOC-25,000 g/m-3-135 dTv. Optimal pollutant values (corresponding to PD = 20%) and admissible values (PD = 30%) for unadapted and adapted persons are calculated. Long-term tolerable values (determining the sick building syndrome range) and short-term tolerable values (the beginning of the toxic range) are also stated. The same system used to evaluate noise can be used to evaluate air quality. Additionally, the contribution of the individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The new units dCd and dTv can express an increase or decrease in air contamination, e.g. by the use of air cleaners, new building materials etc. The proposed system of using dCd and dTv is compatible with BSR/ASHRAE 62-1989 R which can be used to determine the required volume of fresh air for ventilation by an improved method, which takes into account different levels of required indoor air quality.

Air Pollution, Indoor↗
PubMed1997

Evaluation of indoor air quality using the decibel concept. Part I--proposal of new units.

Weber-Fechner's law concerning the perception of sound by man with time expressed as a logarithmic function can also be used for the odour constituent used in the evaluation of indoor air quality in buildings. A new unit dB (odour) based on the concentration of Total Volatile Organic Compounds (TVOC) is proposed as it is currently the basis for determining the air change rate. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human small sensors is equal to one and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and a threshold concentration (TVOC) of 50 micrograms/m3-0 dB (odour). The upper limit is determined by the initial value of toxicity TVOC-25,000 micrograms/m3-135 dB (odour). Optimal values corresponding to PD = 20% (according to EUR 14449 EN) and admissible values corresponding to PD = 30% (see Table 3) are proposed, therefore the same values used to evaluate noise can be used to evaluate air quality and additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The determination of the required volume of fresh air for ventilation and air-conditioning systems according to the new principles is the subject of the Part II of this paper.

Acoustics↗
PubMed1997

Evaluation of indoor air quality using the decibel concept. Part II-ventilation for acceptable indoor air quality.

Weber-Fechner's law concerning the perception of sound by man with time expressed as a logarithmic function can also be used for the odour constituent used in the evaluation of indoor air quality in buildings. A new unit dB (odour) based on the concentration of Total Volatile Organic Compounds (TVOC) is proposed as it is currently the basis for determining the air change rate. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to one and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and a threshold concentration (TVOC) of 50 micrograms/m3-0 dB (odour). The upper limit is determined by the initial value of toxicity TVOC -25,000 micrograms/m3-135 dB (odour). Optimal values corresponding to PD = 20% (according to EUR 14449 EN) and admissible values corresponding to PD = 30% (see Part I of this paper) are proposed, therefore the same values used to evaluate noise can be used to evaluate air quality and additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained.

Acoustics↗
PubMed1997

The assessment proposal for long-term and short-term tolerable hygrothermal microclimatic conditions.

A group of four efficient mine rescuers 25 to 35 years old were exposed to a load of a cyclo-ergometer (stages A and B) and a hand ergometer (stage E) in a climate chamber. The total 120 min period of work was divided into four work intervals, 30 min each. There were 5-min breaks between the individual intervals. The load on the ergometer was selected in the range of 25 to 150 W, Tg=20 to 40 degrees C, rh=40 to 80% and v(a)=0.2 to 1.5 m x s(-1). The thermal resistance of the working suit was 0.65 clo at stage A, 1.07 clo at stage B and 0.81 clo at stage E. A total of 200 experiments with 50 combinations of the work and climate loads were made. The heart rate, oxygen consumption, carbon dioxide production, body temperature, skin temperature, water loss by sweating and perspiration, dry and wet bulb air temperature, air velocity and globe temperature were measured during the experiments. The expected production of sweat (SR) and the amount of accumulated heat in the body (Qmax) were calculated for each combination of the work-climate conditions by a computing program ISO 7933:1989 as well as by our own program. Good agreement was reached between the measured and predicted SR values, calculated by the ISO program (r=0.871) as well as between the values calculated by the two programs, respectively (r=0.985). The experimental results have shown good agreement between the predicted and actually measured values of temperature of the body core as an index of short-term tolerable climate load. The values of short-term tolerable time of work calculated at the level of accumulated heat in the body of 50 W x h x m(-2) resulted in an increase of body core temperature by 0.8 to 1.0 K. The values of heart rate did not mostly exceed 140 beats/min, reaching in exceptional (three) cases values above 150 beats/min. The authors recommend to limit the long-term work-heat (climatic) load during a higher metabolic rate (M >80 W x m(-2) including the basal metabolic rate) of acclimatized males and females at a sweat rate SR=270 g x h(-1) x m(-2), of non-acclimatized persons at SR=206 g x h(-1) x m(-2). The limit for low metabolic rates (M < or = 80 W x m(-2)) for non-acclimatized and acclimatized persons is proposed for long-term tolerable loads of SR=147 g x h(-1) x m(-2). The short-term tolerable load by heat storage within the organism for all categories is proposed as Qmax=50 W x h x m(-2).

Adult↗
PubMed1992

The human thermoregulation range within the neutral zone.

A mathematical and physical model of thermoregulatory mechanisms has been derived and experimental data are presented for the elements of the model. The thermoregulatory range within the neutral zone has been analyzed by regression analysis of the experimental data. The optimal globe temperature and the adaptational shifts in temperature for winter and summer are also given.

Body Temperature Regulation↗
PubMed1989

An introduction to the theory of NON-uniformity of hygrothermal constituent of the environment.

Non-uniformity of the hygrothermal constituent of the environment (NUN) causes problems not only of hot workplaces in industry, but also in lightweight buildings, and air-conditioned and even ventilated buildings. It is almost impossible to avoid cold draughts, unilateral thermal radiation etc. in such situations. The theory and definition of NUN in space and in time, and NUN climatic (convective, radiant, perspiratory) and NUN conductive are described.

Body Temperature Regulation↗
PubMed1984

The psychological effects on man of air movement and the colour of his surroundings.

The psychological microclimate is a term which is used to describe the specific psychological effects of some environmental agents as well as the psychological effects of other factors of the physical environment (e g, colour of surroundings, etc). This paper considers air motion and colour schemes of space, defines their stress and strain factors, describes the psychological effects - post-strain, and the methodology of their investigation. It further suggests the criteria and limiting and optimum values of the dynamic effect of air (permissible air velocities in interior and exterior environments) and the colour scheme of space (in accordance with the Tektronix standard). In conclusion the paper sums up the possibilities of optimisation of the 'psychological microclimate'.

Journal Article↗
PubMed1982

The effect of the environment of human performance.

The performance of man, for a given level of ability, will be affected by his hygro-thermal, electro-ionic, visual and psychological microclimates. This paper presents the results of studies which demonstrate the effect of the hygro-thermal micro-climate on worker performance. The effects of the other micro-climates on worker performance are also discussed. For tasks with mainly physical activity performance depends upon metabolic heat. For tasks with mainly psychological activities there have, until now, been no specified criteria for determining the effects of the environment on performance. Consideration of the results of studies conducted in working environments clearly shows that environmental conditions can effect the efficiency of workers and hence that there are sound economic arguments for optimising working conditions.

Journal Article↗