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Results for “Respiratory Protective Devices”

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At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Field study of subjective assessment of negative pressure half-masks. Influence of the work conditions on comfort and efficiency.

The aim of this study was to assess the effects of work conditions on the acceptability and efficiency of respiratory protective devices (RPD). The subjective evaluation of comfort, protection, respiratory and visual constraint, and the acceptable duration of wear of six RPDs against dust was achieved by 30 workers during their actual work. Metabolic rate was evaluated for each worker, and dry and wet air temperatures measured in the work area. RPDs objective protection factor was measured during each of the 180 test periods. In the conditions of this study, the acceptable duration of wear was about 1 h. This duration and the comfort parameters were reduced when the air temperature increased. The younger workers and/or smokers were less sensitive to mask discomfort. Objective protection factors of the RPDs are reduced under warmer conditions, and when the metabolic rate is low. Finally, the results of this study also show the poor capacity of standardized leakage tests to assess the objective respiratory protection of workers in the field. Some hypotheses which can explain this fact are discussed.

Adult↗
PubMed2004

Partial protection by respirators on airways responses following exposure in a swine house.

BACKGROUND: Exposure to swine dust leads to an intense airway inflammation and increased bronchial responsiveness. The purpose of the present study was to evaluate the effect of a respiratory protection device during exposure in a swine house. METHODS: Twenty-two subjects, 11 with a respirator, were exposed. Symptoms, body temperature, nasal lavage, and a bronchial metacholine challenge were performed before and 7 hr after exposure. For exposure assessment a nasal sampler was evaluated. RESULTS: The subjects with a respirator showed an attenuated inflammatory nasal response. An increase in bronchial responsiveness was observed in both groups, significantly greater in the unprotected group. The use of respirators reduced endotoxin exposure by more than 90% (assessed by nasal samplers). CONCLUSION: The use of a respirator attenuated the inflammatory response compared with an unprotected group. The minor effect on bronchial responsiveness suggests that gases and/or ultrafine particles may also be important factors.

Adult↗
PubMedDate not supplied

Principles of respiratory protection.

This review describes the various types of respiratory protective devices used in Israel during the Persian Gulf war, and summarizes the relevant physiological concepts of respiratory protection. Physiological principles of modern devices with powered air supply are discussed in detail. Our experience may be useful in the evaluation of new respirators and in finding solutions for problematic subpopulations.

Adult↗
PubMed1995

Suffocation from use of modified gas mask.

We report a case of suffocation caused by use of a gas mask modified by the attachment of a plastic bag with evidence of halothane inhalation. Gas masks and plastic bags are sometimes used to aid in the inhalation of volatile substances. Improper use or modification of gas masks or other respiratory protection devices may result in asphyxial death.

Adult↗
PubMed2002

A review of assigned protection factors of various types and classes of respiratory protective equipment with reference to their measured breathing resistances.

The British Standards Institution 'Guide to implementing an effective respiratory protective device programme' (BS 4275) lists assigned protection factors (APFs) for various types of respiratory protective equipment (RPE). The APFs were allocated either on the basis of available workplace studies data which met set criteria or on the basis of professional judgement that there is equivalence between its operation and that of a device for which an APF is derived from workplace data. However, in many cases no workplace study information exists to support this professional judgement. As an interim measure, pending information based on workplace measurements, the breathing resistance of a range of tight-fitting RPE from negative pressure filtering devices through to self-contained positive pressure breathing apparatus was measured at various breathing rates. The relative inhalation resistances were then compared on the assumption that similar breathing resistance performance is likely to give similar inward leakage on a facepiece and hence similar protection if all other factors, such as fit, etc., are equal. This work indicates that for most devices the allocation of APFs by analogy to other devices seems to be acceptable. However, there appears to be no justification for the allocation of an APF value of 100 to continuous flow compressed air line breathing apparatus. It is recommended that it should be lowered to 40 until there is valid workplace study data to support the current APF of 100. The work provides an informative insight into the relative performance of devices.

Humans↗
PubMed1996

An analytical framework for relating dose, risk, and incidence: an application to occupational tuberculosis infection.

An adverse health impact is often treated as a binary variable (response vs. no response), in which case the risk of response is defined as a monotonically increasing function R of the dose received D. For a population of size N, specifying the forms of R(D) and of the probability density function (pdf) for D allows determination of the pdf for risk, and computation of the mean and variance of the distribution of incidence, where the latter parameters are denoted E[SN] and Var[SN], respectively. The distribution of SN describes uncertainty in the future incidence value. Given variability in dose (and risk) among population members, the distribution of incidence is Poisson-binomial. However, depending on the value of E[SN], the distribution of incidence is adequately approximated by a Poisson distribution with parameter mu = E[SN], or by a normal distribution with mean and variance equal to E[SN] and Var[SN]. The general analytical framework is applied to occupational infection by Mycobacterium tuberculosis (M. tb). Tuberculosis is transmitted by inhalation of 1-5 microns particles carrying viable M. tb bacilli. Infection risk has traditionally been modeled by the expression: R(D) = 1 - exp(-D), where D is the expected number of bacilli that deposit in the pulmonary region. This model assumes that the infectious dose is one bacillus. The beta pdf and the gamma pdf are shown to be reasonable and especially convenient forms for modeling the distribution of the expected cumulative dose across a large healthcare worker cohort. Use of the the analytical framework is illustrated by estimating the efficacy of different respiratory protective devices in reducing healthcare worker infection risk.

Cohort Studies↗
PubMed1987

Protective value of powered dust respirator helmet for farmers with farmer's lung.

Seventeen victims of farmer's lung were monitored during two indoor feeding seasons for cattle. The victims, who had all recovered from the acute phase of the disease before entering the experiment, used powered helmets for respiratory protection (Air-Stream) equipped with Type P2 filters. Filters were changed once a week. The lung function of each subject was investigated at the beginning and towards the end of the indoor feeding season. Each subject kept a diary about the use of dust respirators, changing of filters, inconvenience related to the use of respirators, and symptoms experienced during the follow-up. None of the subjects reported symptoms they related to farmer's lung, and mean values for the lung function parameters (PEF, FEV1, FVC, DLCO, and KCO) did not decrease during the two follow-up periods. In contrast, mean DLCO and KCO increased slightly. At the very end of the both indoor feeding seasons, after the actual follow-up periods, one subject developed mild recurrences of the disease without deterioration detectable by radiology. The patient asserted that he had used the protective helmet properly. The results indicate that powered respirator helmets have protective value in farmer's lung and are appropriate for long-term use. A possibility remains, however, that the disease may recur in highly sensitized individuals, despite the use of efficient protective devices. Other measures for preventing or decreasing mould exposure are equally important.

Adult↗
PubMed1980

System for routine testing of self-contained and airline breathing equipment.

Airline respirators and self-contained breathing equipment are tested in a Shell refinery/petrochemical complex before issue and use of a specially designed system. The pressure-demand devices are tested for: adequate positive pressure inside the facemask during rest and inhalation; sufficient airflow during worker inhalation; and proper operation of the mask exhalation valve. Routine testing after cleaning and maintenance indicates that, although most equipment checks out satisfactorily, the system helps to identify problems that could impair performance. Workers also have added confidence in the respiratory protective equipment because of this testing program.

Aviation↗
PubMed1989

Effects of respirator dead space, inspiratory resistance, and expiratory resistance ventilatory loads.

The effects of respiratorlike inspiratory resistance (IR), expiratory resistance (ER), and dead space (DS) were assessed in a group of 11 normal volunteers during moderate steady-state (SS) and rapidly incremented (RI) exercise. The physiologic effects of IR were predominant, increasing inspiratory time, duty cycle, and several measures of ventilatory work. Effects of DS appear related to increased minute ventilation and include increasing flow rates and duty cycle and requiring greater ventilatory work; during RI exercise, the DS effect became relatively smaller at higher exercise levels. ER compressed expiratory time. These results characterize the response to IR, ER, and DS loads and suggest that DS may be relatively less physiologically significant than IR.

Airway Resistance↗
PubMed1977

Evaluation of Federal man tests for self-contained breathing apparatus.

The transient pulmonary responses to four short duration man tests used in the Federal approval of breathing apparatus were measured. The pulmonary ventilation dropped 30 percent in the first thirty seconds in the periods assigned for samples and readings which were immediately preceded by work. A physiological deficit was incurred during the short duration man tests which meant that less O2 and ventilation were required when compared to steady state responses shown on approval tests. The scheduled man test activities for short duration breathing apparatus should be revised and made more vigorous to match the intended use of escape apparatus.

Adult↗
PubMed1981

Clinical pulmonary function and industrial respirator wear.

This investigation was the initial step in determining a clinical pulmonary test which could be used to evaluate workers as to their suitability to industrial respirator wear. Sixty subjects, 12 superior, 37 normal, and 11 moderately impaired with respect to lung function tests were evaluated with a battery of clinical pulmonary tests while wearing an industrial respirator. The respirator was a full-face mask (MSA-Ultravue) "demand" breathing type equipped with an inspiratory resistance of 85 mm H2O at 85 L/min air flow and an expiratory resistance of 25 mmH2O at 85 L/min air flow. Comparisons of these tests were made between the three groups of subjects both with and without a respirator. It appears that those lung tests which measure the flow characteristics of the lung especially those that are effort dependent are more susceptible to change as a result of respirator wear. Hence, the respirator affects the person with superior lung function to a greater degree than the moderately impaired person. It was suggested that the clinical test of 15 second maximum voluntary ventilations (MVV.25) may be the test of choice for determining worker capability in wearing an industrial respirator.

Adolescent↗
PubMed1982

Physiological response to "pressure-demand" respirator wear.

This investigation determined cardiorespiratory responses of subjects with normal lung function and exercise tolerance and compared them with subjects with moderate impairment of lung function and exercise tolerance. The respirator was an air-line full-face mask (MSA-Ultravue) "pressure-demand" breathing type equipped with an inspiratory resistance of 85 mmH2O at 85 L/min air flow. This resistance was operable in conjunction with the fixed 25 mmH2O inspiratory and expiratory resistance required to pressurize the face piece. Physiologically and subjectively the response of the normal and moderately impaired subjects to respirator wear during rest, 35%, 50% and 80% of their maximal aerobic capacity (VO2max) were not different. However, the pressure swings inside the face piece exceeded 24 cmH2O and resulted in 50% of the subjects being unable to finish 10 minutes of work at 80% VO2max. The greater the ventilatory demand placed upon the respirator due to increasing workload, the more like a "demand" system pressure-flow response the "pressure-demand" system produced. Hence, the concept of increased protection and reduced inspiratory resistance as a result of pressurizing the facepiece during heavy work is seriously questioned.

Adult↗