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At least 91 records · Page 5Linked to original sources
PubMed1985

The quality of respirator programs: an analysis from OSHA compliance data.

The quality of respirator programs in typical workplaces was investigated by analyzing the history of compliance with OSHA Standard 29 CFR 1910.134 (respiratory protection). Analysis was focused on the approximately 47 000 health inspections conducted in the manufacturing industries [Standard Industrial Classification (SIC) Codes 2000-3999] in the period of October 1, 1976 to September 30, 1982. During this period, approximately 27% of inspections in which respirator programs were reviewed resulted in a citation for a specific program deficiency. Of inspected worksites in which respirators were in use to provide protection from concentrations of air contaminants in excess of OSHA Permissible Exposure Limits, 56% had deficiencies in at least one program area. Since the violations were of the type that have been shown to lower the level of protection provided by respirators, many workers may have been exposed to inhalation hazards as the result of ineffective respirator programs.

Air Pollutants, Occupational↗
PubMed1975

The efficiency of protective hoods used by sandblasters to reduce silica dust exposure.

Several types of respiratory protective hoods used by sandblasters were investigated in two steel fabrication yards. MSA Gravimetric Dust Samplers were used to collect respirable dust samples outside and inside hoods during sandblasting. Colorimetric and x-ray diffraction techniques were applied to the samples for free-silica determination. The majority of the sandblasters, who wore various types of air-supplied hoods, were exposed to an average level of silica dust several times higher than the TLV. Sandblasters wearing non-air-supplied hoods were at the greatest risk. Modern well maintained and properly worn air-supplied hoods offered fair protection during sandblasting periods, but the concentration of suspended respirable dust in ambient air during non-blasting intervals exceeded the TLV by several times.

Air↗
PubMed1983

Critical review of international standards for respiratory protective equipment - II. Gas and vapor removal efficiency and fit testing.

The purpose of a Respiratory Protective Equipment (R.P.E.) standard is to assure that a minimum level of performance is reached by the respirator. Standards from a number of countries and standards organizations require that certain specifications are met in construction and that respirators be evaluated by specific performance tests. This is the second of three critical review papers related to respirator standards. We here summarize in tabular form, compare and critically review how the different countries or standards organizations test respirators designed for protection against gases and vapors for leakage due to improper fitting of the respirator facepiece and gas and vapor removal efficiency of the cartridge/canister. Two general aspects as they relate to removal capacity testing are discussed. The first issue deals with the selection of test gases and vapors that best represent the sorptive behavior of a class or group of compounds. The second issue deals with the extrapolation of laboratory testing under rigidly specified conditions to conditions of actual use. Fit testing varies from country to country. The fit testing conditions specified in the various standards are summarized along with a discussion of test material selection, the test panel selection, and the range of controlled test activities.

Air Pollutants, Occupational↗
PubMed1983

Common materials for emergency respiratory protection: leakage tests with a manikin.

In areas where respirators are not routinely used, emergencies (such as fires) may occur in which protection from airborne particles is necessary. The following readily available materials were tested on a manikin connected to a breathing simulator to determine the fraction of an approximately 2-micron diameter aerosol that would leak around the seal between the materials and the manikin's face: cotton/polyester shirt material, cotton handkerchief material, toweling (a wash cloth), a surgical mask (Johnson & Johnson Co., Model HRI 8137), and a NIOSH-approved disposable face mask (3M Corp., Model #8710). The leakage tests were done to supplement the measurements of penetration through the materials reported previously. Leakage fractions were determined by comparing the penetration of the same aerosol for the materials held to the face versus being fully taped to the face. At a breathing rate of 37 liters per minute, mean leakages for the materials ranged from 0.0 percent to 63 percent, depending on the material. Mean penetrations exclusive of leakage ranged from 0.6 percent to 39 percent. Use of nylon hosiery material ("panty hose") to hold the handkerchief material or the disposable face mask to the face was found to be very effective in preventing leakage. Such a combination could be expected to reduce leakage around the handkerchief to about 10 percent or less in practice, and around the mask to less than one percent, which suggests the adaptation and use of such an approach for industrial hygiene.

Dust↗
PubMed1987

Chemical cartridge respirator performance: 1,3-butadiene.

The chemical 1,3-Butadiene recently has been classified as a potential occupational carcinogen; subsequently, a reduction in the 8 hr TWA from 1000 ppm to 10 ppm has been proposed. Substantial quantities of 1,3-Butadiene are produced annually for use in the manufacture of a variety of rubber compounds, foams, resins and chemicals. Existing process environments may present a potential health hazard under the proposed standards, and the need for proper respiratory protection is evident. As a result, the performance of Scott organic vapor (642-OV), organic vapor/acid gas (642-OA) and acid gas (642-AG) twin cartridges has been determined for 1,3 butadiene. A cartridge test system was developed to generate challenge concentrations of 100 ppm and 1000 ppm; an infrared analyzer was used to measure breakthrough at 10 ppm. The residence time modeling concept developed previously was used to produce the performance characteristics for three types of activated carbon for residence times of 0.1 less than or equal to tau less than or equal to 1.0 sec. Kinetic adsorption capacities and adsorption rate constants were computed from this data, and cartridge performance also was predicted. The twin cartridges tested demonstrated reasonable adsorption capacity for 1,3 butadiene. Cartridge service life was found to be inversely proportional to airflow rate; it was reduced at elevated temperature and humidity conditions. Breakthrough times were approximately three times longer at 100 ppm than at 1000 ppm. When clean air was drawn through cartridges saturated with 1000 ppm 1,3 butadiene, desorption occurred readily. The rate of desorption and the peak concentration were found to be dependent upon the temperature, humidity and degree of saturation.

Adsorption↗
PubMed1988

Effects of adsorbed water vapor on the adsorption rate constant and the kinetic adsorption capacity of the Wheeler kinetic model.

A recent trend in occupational safety and health has focused on the use of respiratory protective equipment to supplant engineering controls as the primary means of protecting workers from toxic substances. Respirator adsorbent cartridges have been demonstrated to have a finite capacity to adsorb toxic vapors. The knowledge of when this limit is approached or has been exceeded is crucial to the user. The Wheeler kinetic breakthrough model has been shown to describe accurately organic vapor penetration through beds of activated carbon. The model, however, does not account for competitive adsorption of water vapor or other organic vapors. The investigations reported here demonstrate the effect of adsorbed water vapor on the kinetic adsorption parameters (kinetic rate constant and kinetic saturation capacity) of the Wheeler equation. Adsorbent beds were equilibrated at varying concentrations of water vapor and then challenged with carbon tetrachloride vapor-laden air. Dry carbon had an initial rate constant of 62.5 s-1 and a kinetic adsorption capacity of 0.36 g of adsorbed CCl4/gram (g/g) of adsorbent. These parameters decreased in proportion to the amount of water vapor adsorbed, with the minimum predicted values occurring at 100% relative humidity. The minimum experimental value for the kinetic rate constant was 17.6 s-1, a decrease of 73% from the dry carbon values. The minimum predicted value for the kinetic adsorption capacity was 0.16 g/g, a decrease of 45%.

Adsorption↗
PubMed1983

Do pressure-demand breathing systems safeguard against inward leakage?

Rescue operations conducted in toxic atmospheres require respiratory protective equipment capable of providing a very high degree of protection. A slight positive pressure in the facepiece throughout the breathing cycle is used in the pressure-demand, compressed-air breathing apparatus to eliminate any inward leakage. In the present work an inward leakage test with sulphur hexafluoride (SF6) was used to measure facepiece penetration in a pressure-demand system at different work loads. During the test, inspiratory-flow pressure variations within the facepiece and heart rate were also measured. Tests were performed on a dummy head and on two subjects. In some tests a poor face seal was introduced by putting an open tubing with an inner diameter of 2 mm and outer diameter of 3 mm under the sealing edge of the mask. It was found that inward leakage was less than 0.0001% under all conditions as long as facepiece pressure was positive. When facepiece pressure fell below zero, which occurred at inhalation peak flows about 300 L/min, an inward leakage was detected. One subject achieved, at extreme work load, an inhalation peak flow around 450 L/min. These results show that pressure-demand systems should be tested with a breathing machine giving peak flows of at least 300 L/min to ascertain the capability of these systems to maintain positive pressure in the facepiece during hard rescue work.

Adult↗
PubMed1983

Critical review of international standards for respiratory protective equipment - I. Respiratory protective equipment for particulate-laden atmospheres.

The standards for respiratory protective equipment (R.P.E.) from eleven countries and standards organizations were grouped according to type as particulate removing, gas and vapor removing, airline (fresh air hose and compressed air types), and self-contained breathing apparatus (open circuit and closed circuit). Each group of standards was further divided into specification and performance requirements. This paper is one in a series of three that highlights and critically reviews international respirator standards; it deals specifically with R.P.E. for protection against particulate-laden atmospheres. Great Britain, Australia, European Committee for Standardization (CEN), France, South Africa, Italy, Spain, New Zealand, Scandinavia, Japan, and Germany have standards for R.P.E. against particulate-laden atmospheres. Tabular summaries and accompanying discussion of national requirements are presented in the following categories: solid and liquid aerosol removal efficiency, clogging, and rough usage. Large differences and some notable omissions exist among standards. For example, the protection capacity of the filter can be tested by using solid particulate or liquid challenge aerosols. The majority of the countries evaluate protection capacity using solid particulate aerosols, while the remainder use both solid and liquid or liquid aerosols only. Other differences in filter testing deal with the composition of the test aerosol and the characteristic of the filter measured. The initial penetration or the penetration of the filter as it is being loaded over a specified period of time can be measured. In the latter case penetration is averaged over the test period and the degree of protection is assessed only for that overall time period; information is not provided concerning the protection afforded by the filter in the earlier stages of use.

Aerosols↗
PubMed1983

Correlation of qualitative and quantitative results from testing respirator fit.

Three qualitative respirator fit tests were evaluated for their ability to adequately measure respiratory protection. The evaluated methods were the negative pressure test, the isoamyl acetate test, and the irritant smoke test. Each test was performed concurrently with a single quantitative fit test, the dioctylphthalate (DOP) test, during 274 half-mask and 274 full facepiece wearings. The quantitative values of DOP penetration obtained after passing or failing each qualitative fit test were lognormally distributed. For each qualitative test performed on each mask type, the average log penetration values obtained after passing and failing each test were statistically different from each other. The mean of the log penetration values associated with the failed qualitative test was always larger than the mean of the log penetration values associated with passed qualitative tests for all three qualitative methods. Most (95%) of the tested study had adequately fitting respirators as determined by quantitative testing. Of these subjects, 96% to 100% passed the qualitative fit tests. Of the 5% of the study subjects with inadequately fitting half mask respirators, 93% to 100% of the inadequate fits were detected by qualitative methods. Twenty three to 46% of the poorly fitting full face masks were detected by qualitative methods. The probability of passing or failing a qualitative test with an inadequately fitting respirator can be estimated; however, the uncertainty associated with each estimate is large due to the small number of study subjects with poorly fitting respirators.

Adult↗
PubMed1983

Critical review of international standards for respiratory protective equipment - III. Practical performance tests.

This paper, the third in a series of papers devoted to review of international standards for Respiratory Protective Equipment (R.P.E.), summarizes in tabular form, compares, and critically reviews standards of different countries or organizations pertaining to practical performance tests (Man Tests). There are similarities, differences and omissions in the national standards that deserve attention. Of the countries or organizations that require Man Tests on particulate and/or gas and vapor respirators, none described in detail the tests to be performed. For example, CEN requires that Man Tests be conducted on gas/vapor respirators under realistic conditions to determine imperfections that cannot otherwise be determined by other performance tests, but does not stipulate the testing procedure. With respect to fresh-air hose, compressed-air line and self-contained breathing apparatus R.P.E., only Great Britain and CEN present specific Man-testing requirements in detail. Man Tests for all types of R.P.E. have a specific purpose: to determine any imperfections in, or malfunction of the apparatus under simulated work conditions. One major difference, however, is in the kind of work simulation activities required. In the testing of fresh-air hose and compressed-air line respirators, for instance, CEN describes in great detail, a variety of activities to be conducted. Great Britain merely states that the subjects shall work in practical conditions. Another important disparity relates to the conditions under which the test is to be performed. For example, CEN requires a heavy-duty test and a cooled chamber test, as well as tests under normal and low temperature conditions. Great Britain, on the other hand, requires only the latter two tests. Still other differences lie in the kinds of medical surveillance required during testing and the evaluation criteria used for assessment.

Air Pollutants, Occupational↗
PubMed1984

[Evaluation of the degree of protection provided by a cartridge-mask system during working with asbestos].

During removal of sprayed-on asbestos coating workers are exposed to high airborne fiber concentrations. The true protection of negative pressure respirators under working conditions was evaluated during an asbestos abatement project. A modification allowing air sampling inside the mask is described. The values for samples collected inside a full-face mask ranged between 0.4 and 5% of the concentrations measured outside. These values were considerably lower than those found inside a half-mask.

Asbestos↗
PubMed1989

[The "high concentration" oxygen mask: a dangerous defect].

Three cases of unidirectional valve inversion in airtight oxygen masks are reported. These defects were discovered before use on a patient. One of the masks was tested on a healthy volunteer. It resulted in the rupture of the reservoir bag, with a oxygen leak and decrease in FiO2. Checking the valve before use is therefore mandatory, and fabrication procedures should be revised.

Equipment Failure↗
PubMed1990

The Brain laryngeal mask. An alternative to difficult intubation.

We report the case of a young man undergoing fixation of bilateral mandibular fractures, where the anaesthetist was unable to intubate. A Brain laryngeal mask was employed, thus enabling surgery to proceed. This relatively new device enabled the airway to be safeguarded whilst preserving reasonable surgical access for the attachment of Erich arch bars and a four hole osteosynthetic bone plate. The surgical and anaesthetic procedures are summarised. The laryngeal mask is described and its performance and limitations are discussed. We believe this to be the first report of mandibular fracture fixation performed with a Brain laryngeal mask in situ.

Adult↗
PubMed1975

Respirator compensation of a portable air monitor.

A respirator-compensated, portable air-monitor has been devised by modifying a commercially available personal air sampling pump. A switching circuit box, integrated into the sampling pump electrical system and activated by a micro switch mounted within the respirator mask, turns the pump off and a timer on whenever the respirator is worn. Thus, valid measurements of an individual worker's environmental exposures can be made even though that worker uses a respirator at his own discretion.

Air Pollutants, Occupational↗
PubMed1975

A successful respirator program.

This discussion covers the successful implementation of a respirator program on a voluntary basis in a large industrial plant. The program had the stated objective of mandatory usage at the end of a specified period of time. It was successfully implemented in an 1100-man department. This practical approach is applicable to large and small plants.

Attitude↗