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At least 19 recordsLinked to original sources
PubMed1990

Thermal discomfort of respiratory protective devices.

Respiratory protective devices which would protect the wearer against noxious material and gases are not worn in many of the appropriate circumstances. They have been said to feel uncomfortable and hot. In the present study, six men and six women in a 25 degrees C room reported on facial discomfort, thermal sensation, and sweating while wearing three different types of half-facepiece respirators requiring tidal airflow. Skin temperature of the face was measured using a thermocouple taped to the nasolabial fold. The subjects reported that the face felt comfortable when the skin temperature was 34 degrees C or below. However, at skin temperatures above 34.5 degrees C, the face felt increasingly warm, uncomfortable, and sweaty. This finding is similar to that reported previously when subjects wore a half-facepiece respirator supplied continuously with warm, humid air. The conclusion is that thermal conditions of the face contributed to, and may possibly dominate, the discomfort of wearing respiratory protective devices.

Adult↗
PubMed1980

A new respiratory protective device.

This paper describes a new respiratory protective device for use in dangerous environments. The new system provides a lightweight alternative to present compressed air systems and a safe alternative to present pure oxygen respirator systems. The new system utilizes electronically controlled valves, two breathing bags, and a small, compressed supply of oxygen-rich air to achieve these goals. A prototype backpack system very adequately demonstrated the feasibility of such a system as a useable device for respiratory protection.

Environmental Exposure↗
PubMed1977

Minimum protection factors for respiratory protective devices for firefighters.

Carbon monoxide and oxygen concentrations were measured in seventy-two structural fires using a personal air sampler carried by working firefighters. In a total sampling time of 1329 minutes the carbon monoxide concentration exceeded 500 ppm approximately 29 percent of the time. The maximum carbon monoxide concentration was 27,000 ppm and in 10 percent of the fires, the maximum concentration exceeded 5500 ppm. Only six runs indicated oxygen concentrations less than 18 percent. On the basis of these exposure data, a minimum protection factor of 100 is proposed for breathing apparatus for structural firefighting.

Air↗
PubMed1989

Effect of thermal conditions on the acceptability of respiratory protective devices on humans at rest.

The physiological and subjective responses of six sedentary subjects wearing half-facepiece respirators were observed over a wide range of room and respirator air conditions. Room air and dew-point (Ta:Tdp) temperatures were 25:11 degrees, 30:13 degrees, and 35:16 degrees C in still air. Respirator air temperatures were maintained independently of room conditions at 27 degrees, 30 degrees, 33 degrees, and 36 degrees C with relative humidity levels of 47% and 73%. Physiological measurements included local skin and dew-point temperatures. Subjective judgments of acceptability, thermal sensation, degree of discomfort, sense of skin moisture, and difficulty of breathing were recorded separately for the thermal environment in the room and inside the respirator. Respirator temperatures cooler than 33 degrees C were always comfortable and 100% acceptable; respirator air temperatures above 33 degrees C or higher humidity levels decreased respirator acceptability. Acceptability of the respirator environment decreased as lip temperature increased above 34.5 degrees C or when respirator dew-point temperature increased above 20 degrees C. Increased respirator air temperature and humidity often made breathing seem "slightly hard." The respirator conditions influenced the subjects' judgment of the acceptability of the surrounding thermal environment.

Adult↗
PubMed1983

External inspiratory resistance of protective respiratory devices: effects on physical performance and respiratory function.

Twenty subjects wearing protective respirators were studied during submaximal exercise (80% of VO2max) on a treadmill. The protective devices were fitted with canister filters of low expiratory resistance and different inspiratory resistances: (0.3, 1.8, 2.8, 3.4, 3.9, and 4.6 cm H2O X sec/liter). The effect of inspiratory resistance on physical endurance, various physiological parameters, and subjective sensations was examined. With the increase in inspiratory resistance, a significant decrease in physical performance, decrease in tidal volume, increased ratio of inspiratory to expiratory time, increased peak inspiratory pressure, and increased CO2 retention were observed. The difficulty in inspiration correlated significantly to inspiratory resistance and seems to be the main reason for cessation of the effort. No acceptable upper limit for the inspiratory resistance of the canister filters was found. Any decrease in the inspiratory resistance of the mask's filter enhanced endurance and performance.

Adult↗
PubMed1978

[Selection of suitable individual respiratory protective devices in relation to workroom environment].

Adopting individual respiratory protective equipments, even if in those limited situations in which they are justified, must be consequent to a selection related with the nature of the pollutants to which the operator is, or may be, exposed, with the peculiarity of the workroom environment and, lastly, with the degree of security to be achieved. This statement is not to be neglected even if all respiratory protective equipments are fit to meet the suggestions of qualified standard making institutions. The same is to be considered of capital importance in Italy where the lack of legislation as far as omologation is concerned, allows products not fit to guarantee the request for security which are, consequently, not only superfluous, but dangerous for wearers. For these reasons it has been considered useful to illustrate the characteristics and proper application-fields of the most widely spread respiratory protective equipments referring, as far as possible, to the recommendations being prepared on the matter by the CEN (European Committee for Standardization).

Air Pollutants↗
PubMed1990

[Comparison of the protective action of 2 respiratory protective devices in farmers with farmer's lung].

With the aid of provocative challenges with hay in patients suffering from farmer's lung, a comparison of the protective effectiveness of the Airstream Helmet (main filter P2) and of the Sundström Mask (main filter P3) was undertaken. A total of 42 farmers were admitted to the study. In 14, as indicated by an expertise, a workplace-related provocative challenge by the farmers' own hay was carried out and was shown to be positive with respect to the presence of farmer's lung disease. In 28 farmers in whom an inhalative provocative challenge with hay had been demonstrated to be positive, inhalative provocative challenges were again performed using the farmers' own hay while the farmers were wearing protective respirators--14 with the Airstream Helmet, (main filter P2) and 14 with the Sundström Mask (main filter P3). When the respirator was not worn, a statistically significant increase in the number of leukocytes and temperature vis-a-vis the baseline values was observed. Partial oxygen pressure, vital capacity, total lung capacity and DCO, all showed a statistically significant decrease as compared with the baseline figures. The provocative challenges performed while the subjects were wearing the respirators also revealed a statistically significant increase in the number of leukocytes and in temperature, which, however, was statistically significantly smaller than that induced by provocation without the respirator. A similar pattern of behaviour was also found in the decrease in vital capacity, oxygen partial pressure, total lung capacity and DCO. No statistically significant differences were observed between the provocation figures obtained with the Airstream Helmet as compared with those obtained with the Sundström Mask.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchial Provocation Tests↗
PubMed1982

Physiological and psychological adaptation to respiratory protective devices.

This study was conducted to investigate the adaptation process to respiratory protective devices (RPD). Twenty healthy subjects were tested at 80% of their Vo2 max for 6 consecutive days with a fitted RPD with an airway resistance of 2.80 +/- 0.07 cm H2O s/1. It was concluded that working with RPD at a work capacity close to maximum for several minutes per day induces a rapid adaptation process. This is demonstrated by an improvement in physiological parameters rather than in subjective sensations.

Adaptation, Physiological↗
PubMed1996

A method for measuring the CO2 dead space volume in facial visors and respiratory protective devices in human subjects.

The external CO2 dead space volume (Vd) in facial visors and respiratory protective devices is difficult, but important, to measure in human subjects. The lack of proper methods for its assessment has hampered the development of standards and the improvement of visor and device design. We have improved and evaluated a method for measuring Vd and the mean inspired fraction of CO2 (FI,CO2) in human subjects wearing facial visors or respiratory protective devices. The method is based on indirect measurements of inspiratory volumes using a calibrated respiratory inductive plethysmograph (RIP), and measurements of FCO2 with a mass spectrometer. The accuracy of the RIP method was assessed in eight subjects and its repeatability was studied during nasal and oral breathing, at rest and after bicycle ergometer work. We related the Vd,RIP results to two known external VdS (with the effective Vd equal to the geometric volume; 15 ml and 320 ml), through which the subjects breathed, using RIP and a pneumotachometer (PTM) simultaneously (Vd,RIP and Vd,PTM). The repeatability of Vd and mean FI,CO2 results was determined from duplicate recordings during the wearing of a welding visor. Initial RIP calibration was accepted if the inspiratory tidal volume error was < or = 10%. This resulted in an acceptable Vd,RIP error (< or = 20%; Vd = 320 ml) in six eight subjects. The validation technique allowed us to separate the Vd,RIP error into a volumetric error and an error related to CO2 measurement. Poor RIP volumetric accuracy over the initial portion of inspiration was detrimental to Vd accuracy. Using the welding visor, Vd and mean FI,CO2 were less at rest than after work and less during nasal breathing than during oral breathing. The intra-individual variability of Vd and mean FI,CO2 were lower during nasal breathing than during oral breathing. To summarize, the improved RIP based method can accurately (< or = 20% error) assess Vd and mean FI,CO2 in facial visors and respiratory protective devices in standardized work situations. A meticulous RIP calibration procedure and repeated validations of RIP volume and CO2 measurement accuracy must, however, be applied.

Adolescent↗
PubMed1995

An evaluation of respiratory protective devices used in children's evacuation.

This study evaluated respiratory protective devices (RPDs) used in children's evacuation. The RPDs evaluated were either a protective jacket or a protective mask. One hundred and sixty children participated. Half were evacuated from home with the help of their parents, whereas the other half were evacuated from day-care centres with the help of staff. In all, 65% of the children were evacuated wearing their RPDs. No significant differences were found between the two environments, but significantly more children (75%) kept the mask on than the jacket (55%). However, many more cases of improper fit after dressing were observed with the mask than with the jacket. Speech communication was observed to be reduced for 58% of the children, wearing the mask, and slightly more for those wearing the jacket. Children who did not evacuate with the RPDs on were observed to be more anxious and adults' attitudes towards them were rated as more neutral, whereas children who successfully evacuated were less anxious and adults' attitudes towards them were rated both as more positive and as more negative.

Child↗
PubMed1984

Cardiorespiratory effects of respiratory protective devices during exercise in well-trained men.

The effects of a filtering device, an air-line breathing apparatus and a self-contained breathing apparatus ( SCBA ) on pulmonary ventilation, oxygen consumption and heart rate were studied in 12 well-trained firemen aged 21-35 years. Their average maximal oxygen consumption (VO2 max) was 64.9 ml X min-1 X kg-1. Sequential tests without and with the respirator were performed on a treadmill. The continuous test contained five components, each of which lasted 5 min: sitting at rest, walking at 20%, 40%, and 60% of the individual VO2 max, and recovery sitting. During the higher submaximal work levels and recovery, ventilation, heart rate, and oxygen consumption in particular increased more with respirators than without them. At the highest work level the increments in oxygen consumption caused by the respirators were 13%, (8.7 ml X min-1 X kg-1), 7% (4.4 ml X min-1 X kg-1), and 20% (12.7 ml X min-1 X kg-1) of VO2 max. All three respirators hampered respiration, resulting in hypoventilation. The additional effort of breathing and the weight of the apparatus (15 kg with the SCBA ) increased the subjects' cardiorespiratory strain so clearly that the need for rest periods and the individual's work capacity when the respirators are worn must be carefully considered, particularly with the SCBA .

Adult↗
PubMed1984

Physiological effects associated with the use of respiratory protective devices. A review.

Several types of filtering (air-purifying) devices, air-line (supplied-air) apparatus, and self-contained breathing apparatus are used at work. The most important parameters of the respiratory protective devices that affect physical work capacity are additional inspiratory and expiratory breathing resistance, dead space, and weight. The main physiological effects of the respirators are alterations in breathing pattern, hypoventilation, retention of carbon dioxide, and increase in the work of breathing. The undesirable effects are accentuated during heavy physical work, maximal physical work capacity thereby being reduced.

Equipment Design↗
PubMed1998

Selecting an adequate respiratory protective device: the choice between a respirator and breathing apparatus.

An adequate respiratory protective device should keep the concentration of the pollutant inside the facepiece below the appropriate occupational exposure limit. Filtering respirators will not provide adequate protection if the device fails in an atmosphere which is immediately dangerous to life or health (IDLH). It has therefore been suggested that in contaminant concentrations above an IDLH level it is more appropriate to select breathing apparatus with an emergency breathing facility. In this paper IDLH levels published by the US National Institute of Occupational Safety and Health have been compared with UK occupational exposure limits. For some substances there was a relatively small difference between the IDLH level and the short-term occupational exposure limit (STEL). The median ratio of the IDLH level to the STEL was 10 for gases and vapours and 50 for aerosols. For almost half the substances with UK occupational exposure limits there is no IDLH value. It is concluded that the published IDLH concentrations are, on their own, an insufficient basis for selecting breathing apparatus over a filtering respirator. It is equally important to consider the likelihood that a filtering device may fail catastrophically since this determines the risk from wearing a respirator in an IDLH atmosphere. More emphasis should be placed on the control of potentially high exposure levels by means other than respiratory protection.

Equipment Failure↗
PubMed1994

Respiratory protective devices--NIOSH. Notice of proposed rulemaking.

This proposed rule addresses NIOSH's and the Department of Labor/Mine Safety and Health Administration's (MSHA) certification requirements for respiratory protective devices. Specifically, the proposal would replace existing MSHA regulations with new public health regulations, while also upgrading current testing requirements for particulate filters. This action is the first of a series of modulates which will, over the next several years, upgrade current respirator requirements. This modular approach will allow improvements to be implemented on a priority basis as well as facilitate adaptation to new requirements by the manufacturers and users of respirators. Except for the particulate-filter requirements, most requirements of existing regulations would be incorporated into the new regulations without change. The proposed testing requirements for particulate filters would significantly improve the current approach to evaluating the effectiveness of an air-purifying respirator's filter to remove toxic particulates from the ambient air, updating existing provisions to be consistent with two decades of advances in respiratory protection technology. The certification of air-purifying respirators under these proposed requirements would also enable respirator users to select from a broader range of certified respirators that meet the current performance criteria recommended by CDC for respiratory devices used in health-care settings for protection against Mycobacterium tuberculosis, the infectious agent that causes tuberculosis (TB). This Notice also announces an informal public meeting on the proposed rule, as indicated below. Elsewhere in this issue of the Federal Register, MSHA is publishing a proposal to remove existing regulations at 30 CFR part 11, which would be made obsolete by a final rule resulting from this proposed rule.

Guidelines as Topic↗
PubMed1991

Psychological effects on prolonged use of respiratory protective devices in children.

In the study of psychological effects of prolonged use of a respiratory protective device (RPD), forty 7-10-year-olds, fifty 12-15-year-olds and twenty-eight 17-20-year-olds participated as subjects. Subjects in the experimental groups wore a full-face mask provided for civil defence in Sweden, and subjects in the control groups wore a filtering facepiece consisting of a tissue material covering the nose and mouth. Subjects in both groups tended to terminate at the same time, implying that breathing resistance may not be an important obstacle to prolonged wear of the full-face mask. In the experimental groups 97% wore the mask for at least 1.5 h, 77% for at least 2.5 h and 54% for the full 6-h session. About 50% of subjects in the younger age groups terminated in the interval between 1.5 to 3.5 h, whereas the corresponding figure in the older age group was about 30%. Boredom may have played an important role for decisions to terminate, perhaps in part because the mask interfered with speech communication. Discomfort due to pressure on the nose, the chin and the forehead was also reported, more frequently by the older than by the younger subjects.

Adolescent↗
PubMed1993

Respiratory health status in swine producers using respiratory protective devices.

A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, between-group comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection.

Adult↗