ABSTRACT
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Three respirator full face masks with different paripheral seal designs (flat, inner flap, and pneumatic) were modified to permit study of the facial seal component. Twelve subjects participated in the study. Each subject completed a... more
Three respirator full face masks with different paripheral seal designs (flat, inner flap, and pneumatic) were modified to permit study of the facial seal component. Twelve subjects participated in the study. Each subject completed a three-hour test session on each mask. The first half of each session was devoted to a study of leakage at five seating forces; the second half of the session was devoted to a comfort study of the same mask under the same five seating forces. To test for the differences in' leakage for a given seating force a uranine aerosol test was used to challenge the integrity of the facial seal and permit quantitative measurement of percent leakage. Differences in apparent seating force (and therefore comfort) between the three facial seal designs were studied utilizing a psycho-physical technique. A suggested physiological correlate of comfort, galvanic skin potential, was also measured during the second half of the session. Significant differences were noted in the performance of one of the three masks as demonstrated by the leakage tests. The psycho-physical evaluation did not reveal significant differences between the masks; however, significant differences were revealed by the galvanic skin potential measurements.
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In-place filter testing is a widely accepted practice for assuring performance of high-efficiency particulate air (HEPA) filter systems. American Society of Mechanical Engineers (ASME) standards address aspects of uncertainty in in-place... more
In-place filter testing is a widely accepted practice for assuring performance of high-efficiency particulate air (HEPA) filter systems. American Society of Mechanical Engineers (ASME) standards address aspects of uncertainty in in-place filter test results through limits on spatial variation of test aerosol concentration and flow velocity. This article augments the standards by developing an approximate expression for test result uncertainty.
Research Interests:
... William C. Hinds and Nani P. Kadrichu Center for Occupational and Environmental Health, Department of Environmental Health Sciences, UCLA School of Public Health, Los Angeles ... Loading decreases the protection provided by... more
... William C. Hinds and Nani P. Kadrichu Center for Occupational and Environmental Health, Department of Environmental Health Sciences, UCLA School of Public Health, Los Angeles ... Loading decreases the protection provided by respirators using high efficiency (DFMR) filters. ...
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ABSTRACT
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... William C. Hinds* and Nani P. Kadrichu CENTER FOR OCCUPATIONAL AND ENVIRONMENTAL HEALTH, DEPARTMENT OF ENVIRONMENTAL HEALTH ... Modern glass fiber filters using micrometer or submicrometer fibers can achieve high efficiency with... more
... William C. Hinds* and Nani P. Kadrichu CENTER FOR OCCUPATIONAL AND ENVIRONMENTAL HEALTH, DEPARTMENT OF ENVIRONMENTAL HEALTH ... Modern glass fiber filters using micrometer or submicrometer fibers can achieve high efficiency with ac-ceptable ...
Research Interests:
Workers in occupations such as mining, wood working, spray painting, pesticide application, and metal grinding are exposed to large particles in the 10 to 150-μm particle size range. For sampling large particles such as these, the... more
Workers in occupations such as mining, wood working, spray painting, pesticide application, and metal grinding are exposed to large particles in the 10 to 150-μm particle size range. For sampling large particles such as these, the American Conference of Governmental Industrial Hygienists has recently adopted criteria for inhalable particulate mass (IPM) sampling. Measurements of inhalability and IPM sampler performance are
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An overview of the properties of suspended particles is given, considering gas properties, particle size, acceleration, and uniform and curvilinear particle motion. Particle adhesion, Brownian motion and diffusion, and radiometric forces... more
An overview of the properties of suspended particles is given, considering gas properties, particle size, acceleration, and uniform and curvilinear particle motion. Particle adhesion, Brownian motion and diffusion, and radiometric forces (such as thermal) are discussed. Attention is also given to such areas as filtration, concentration measurement, condensation and evaporation, and test aerosol production. The interactions of particles with the suspending gas, other particles, and electromagnetic radiation are considered, and the electrical and optical properties of aerosols are also discussed.
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Page 1. comments rn rn . Ambient tlobacco smoke measurement MELVIN W. FIRST, Sc.D. and WILLIAM C. HINDS, Sc.D. Harvard School of Public Health, Boston, MA 021 15 The annoyance caused by ambient tobacco smoke ...
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This paper describes the design and evaluation of a bench-scale aerosol test chamber. Although originally designed for respirator testing, the chamber has broad applications for industrial hygiene research, testing, and calibration. The... more
This paper describes the design and evaluation of a bench-scale aerosol test chamber. Although originally designed for respirator testing, the chamber has broad applications for industrial hygiene research, testing, and calibration. The 109 L chamber includes a top mixing section, a honeycomb flow laminator section, a 52 L transparent plastic aerosol test section, and a bottom exhaust plenum. Overall chamber
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This chapter examines the role of industrial hygienists in preventing pulmonary disease. As part of a team, these environmental specialists are trained to anticipate, recognize, evaluate, and control environmental health hazards in the... more
This chapter examines the role of industrial hygienists in preventing pulmonary disease. As part of a team, these environmental specialists are trained to anticipate, recognize, evaluate, and control environmental health hazards in the workplace. Lung diseases, caused by exposure to airborne chemicals in the form of dusts, mists, gases, and vapors, are among the most serious health hazards facing industrial workers and consequently are an important consideration for industrial hygienists.
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Test aerosols of di(2-ethylhexyl)phthalate (DOP) produced by the Laskin nozzle aerosol generator are widely used for in-place filter testing and respirator fit testing. Concern about health effects of DOP has led to a search for... more
Test aerosols of di(2-ethylhexyl)phthalate (DOP) produced by the Laskin nozzle aerosol generator are widely used for in-place filter testing and respirator fit testing. Concern about health effects of DOP has led to a search for substitute materials for use as a test aerosol. Aerosols were generated with a Laskin generator and diluted 4800-fold with clean air. Size distributions were measured for DOP, di(2-ethylhexyl)sebecate, polyethylene glycol, mineral oil, and corn oil aerosols with a PMS ASAS-X optical particle counter. Distributions gave count median diameters from 0.22 to 0.30 µm. Size distributions varied little with aerosol material, operating pressure, or liquid level. Mineral oil and corn oil gave the closest agreement to the DOP size distribution.
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Occupational exposure to wood dust can cause irritation, dermal or respiratory sensitization, and nasal cancer. These effects have been observed as a result of exposure to dusts from hardwood and softwood, and, except for nasal cancer, to... more
Occupational exposure to wood dust can cause irritation, dermal or respiratory sensitization, and nasal cancer. These effects have been observed as a result of exposure to dusts from hardwood and softwood, and, except for nasal cancer, to sapwood fungi. Wood dust typically has a ...
This paper describes the design and evaluation of a bench-scale aerosol test chamber. Although originally designed for respirator testing, the chamber has broad applications for industrial hygiene research, testing, and calibration. The... more
This paper describes the design and evaluation of a bench-scale aerosol test chamber. Although originally designed for respirator testing, the chamber has broad applications for industrial hygiene research, testing, and calibration. The 109 L chamber includes a top mixing section, a honeycomb flow laminator section, a 52 L transparent plastic aerosol test section, and a bottom exhaust plenum. Overall chamber
Page 1. comments rn rn . Ambient tlobacco smoke measurement MELVIN W. FIRST, Sc.D. and WILLIAM C. HINDS, Sc.D. Harvard School of Public Health, Boston, MA 021 15 The annoyance caused by ambient tobacco smoke ...
Research Interests:
Research Interests:
An understanding of the factors influencing respiratory deposition of cigarette smoke in smokers is needed to accurately control this important source of respiratory exposure in epidemiological studies of workers. Only a few studies have... more
An understanding of the factors influencing respiratory deposition of cigarette smoke in smokers is needed to accurately control this important source of respiratory exposure in epidemiological studies of workers. Only a few studies have characterized the deposition of cigarette smoke in smokers and these involve methods that interfere with normal smoking. A technique for measuring puff volume, inhaled amount, and respiratory deposition of cigarette smoke particulate phase has been developed. It provides satisfactory accuracy (+/- 10%) and causes minimal disruption of normal smoking pattern. The technique captures exhaled smoke with an exhaust hood and establishes the amount of inhaled smoke by monitoring puff volume, puff duration, and puff timing and replaying the exact smoking sequence with matched cigarettes. Mass of captured cigarette smoke is evaluated by fluorophotometry. Preliminary trials with 11 paid volunteers gave an average puff volume of 53 mL and smoke deposition rang...
Research Interests: Tobacco, Humans, Smoking, Female, Male, and 6 moreRespiration, Smoke, Adult, Time Factors, Epidemiologic Studies, and Equipment Design
In-place filter testing is a widely accepted practice for assuring performance of high-efficiency particulate air (HEPA) filter systems. American Society of Mechanical Engineers (ASME) standards address aspects of uncertainty in in-place... more
In-place filter testing is a widely accepted practice for assuring performance of high-efficiency particulate air (HEPA) filter systems. American Society of Mechanical Engineers (ASME) standards address aspects of uncertainty in in-place filter test results through limits on spatial variation of test aerosol concentration and flow velocity. This article augments the standards by developing an approximate expression for test result uncertainty.
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ABSTRACT
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PUBLIC interest has focused on health effects to the large numbers of nonsmokers exposed to tobacco smoke in public places. Recent regulations in a few cities have banned smoking in public places, or have restricted smoking in the manner... more
PUBLIC interest has focused on health effects to the large numbers of nonsmokers exposed to tobacco smoke in public places. Recent regulations in a few cities have banned smoking in public places, or have restricted smoking in the manner of United States commercial ...
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This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of... more
This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of ultrafine particles. Near-continuous data were collected for 5 months at each location. Our data clearly identified Downey as a source site, primarily affected by vehicular emissions from nearby freeways, and Riverside as a receptor site, where photochemical secondary reactions form a substantial fraction of particles, along with local vehicular emissions. In Downey, the diurnal trends of total particle number concentration and elemental carbon (EC) appear to be almost identical throughout the day and irrespective of season, thereby corroborating the role of primary emissions in the formation of these particles. This agreement between EC and particle number was not observed in Riverside during the warmer months of the year, while very similar trends to Downey were observed during the winter months in that area. Similarly, the size distribution of ultrafine particles in Downey was generally unimodal with a mode diameter of 30-40 nm and without significant monthly variations. The number-based particle size distributions obtained in Riverside were bimodal, with a significant increase in accumulation mode as the season progressed from winter to summer. During the warmer months, there was also an increase in sub-100-nm particles in the afternoon hours, between 2:00 p.m. and 4:00 p.m., that also increased with the temperature. The differences observed in the ultrafine particle distribution and temporal trends clearly demonstrated that mechanisms other than direct emissions play an important role in the formation of ultrafine particles in receptor sites of the Los Angeles Basin.
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Research Interests:
Workers in occupations such as mining, wood working, spray painting, pesticide application, and metal grinding are exposed to large particles in the 10 to 150-μm particle size range. For sampling large particles such as these, the... more
Workers in occupations such as mining, wood working, spray painting, pesticide application, and metal grinding are exposed to large particles in the 10 to 150-μm particle size range. For sampling large particles such as these, the American Conference of Governmental Industrial Hygienists has recently adopted criteria for inhalable particulate mass (IPM) sampling. Measurements of inhalability and IPM sampler performance are
Research Interests:
ABSTRACT This article presents results of an experimental validation of a model for predicting the performance of half-mask respirators. The model predicts respirator performance for protection against aerosols. It uses as input the... more
ABSTRACT This article presents results of an experimental validation of a model for predicting the performance of half-mask respirators. The model predicts respirator performance for protection against aerosols. It uses as input the measured fit factor, an estimated work rate, the exposure particle size distribution, and known performance characteristics for the type and brand of filter used. The validation tests involved the measurement of respirator performance, using human subjects, under simulated use conditions with known fit, work rate, particle size distribution, and filter performance. Comparison is made between measured and predicted performance for two conditions each of fit, particle size, and work rate. Fit factors ranged from 5 to 231, test aerosol mass median aerodynamic diameters from 0.6 to 1.3 μm, and work rates from 0 to 50 W. Based on tests conducted here, the predictive model does a reasonable job of predicting penetration under simulated use conditions where fit factor, size distribution, work rate, and filter efficiency are known. It is able to account for 58 percent of variability in measured penetration under the conditions of these tests. The model adequately accounts for the effect of fit (as determined by quantitative fit test), work rate (breathing pattern), and particle size distribution, and shows no bias with the magnitude of these parameters. Given the intrinsic variability of respirator performance measurements, the model is useful for predicting the effect of these variables on respirator performance.
Research Interests:
... William C. Hinds and Nani P. Kadrichu Center for Occupational and Environmental Health, Department of Environmental Health Sciences, UCLA School of Public Health, Los Angeles ... Loading decreases the protection provided by... more
... William C. Hinds and Nani P. Kadrichu Center for Occupational and Environmental Health, Department of Environmental Health Sciences, UCLA School of Public Health, Los Angeles ... Loading decreases the protection provided by respirators using high efficiency (DFMR) filters. ...
Research Interests:
A field study was conducted from April to October 1994 to evaluate worker exposure to carbon monoxide (CO) and oxides of nitrogen (NOx) during offloading of vehicles from car carrier vessels. Personal and area samples for CO and NOx were... more
A field study was conducted from April to October 1994 to evaluate worker exposure to carbon monoxide (CO) and oxides of nitrogen (NOx) during offloading of vehicles from car carrier vessels. Personal and area samples for CO and NOx were taken during offloading operations aboard ten ships dedicated to vehicle cargo. Personal exposure results can be summarized as follows: 20
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The properties and behavior of suspended particles (dust, smoke, clouds), and the physical principles underlying their behavior are covered. Applications such as filtration, respiratory deposition, sampling, and the production of test... more
The properties and behavior of suspended particles (dust, smoke, clouds), and the physical principles underlying their behavior are covered. Applications such as filtration, respiratory deposition, sampling, and the production of test aerosols are discussed. Physical analysis rather than ...
Research Interests: Chemical Engineering, Kinetics, Technology Assessment, Air pollution, Atmospheric sciences, and 11 moreElectromagnetic Radiation, Brownian Motion, Optical Properties, Particle Size, Respiratory System, Electrical Properties, Particle Motion, Particle Acceleration, Particle Size Distribution, Physical Properties, and Aerosol Science
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The effectiveness of increased air motion and dust removal in reducing radon decay product concentration in residences subject to radon intrusion was evaluated in a 78-m3 room under steady-state conditions for air infiltration rates... more
The effectiveness of increased air motion and dust removal in reducing radon decay product concentration in residences subject to radon intrusion was evaluated in a 78-m3 room under steady-state conditions for air infiltration rates between 0.2 and 0.9 air changes per hour. Room-size, portable electrostatic precipitators and high-efficiency fibrous filters were tested as typical residential air cleaning devices; a portable box fan and a ceiling fan were employed as typical residential air movers. Reductions in working levels of 40-90% were found. The fate of radon decay products, with and without mixing fans, was determined by direct measurement. When mixing fans were used, most of the nonairborne potential alpha-energy was plated out on the room surfaces; less than 10% was deposited on the fan blades or housing. Results were compared to a mathematical model based on well-mixed room air, and good agreement was obtained.
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Three respirator full face masks with different paripheral seal designs (flat, inner flap, and pneumatic) were modified to permit study of the facial seal component. Twelve subjects participated in the study. Each subject completed a... more
Three respirator full face masks with different paripheral seal designs (flat, inner flap, and pneumatic) were modified to permit study of the facial seal component. Twelve subjects participated in the study. Each subject completed a three-hour test session on each mask. The first half of each session was devoted to a study of leakage at five seating forces; the second half of the session was devoted to a comfort study of the same mask under the same five seating forces. To test for the differences in' leakage for a given seating force a uranine aerosol test was used to challenge the integrity of the facial seal and permit quantitative measurement of percent leakage. Differences in apparent seating force (and therefore comfort) between the three facial seal designs were studied utilizing a psycho-physical technique. A suggested physiological correlate of comfort, galvanic skin potential, was also measured during the second half of the session. Significant differences were noted in the performance of one of the three masks as demonstrated by the leakage tests. The psycho-physical evaluation did not reveal significant differences between the masks; however, significant differences were revealed by the galvanic skin potential measurements.
Research Interests:
Research Interests:
Research Interests:
... William C. Hinds* and Nani P. Kadrichu CENTER FOR OCCUPATIONAL AND ENVIRONMENTAL HEALTH, DEPARTMENT OF ENVIRONMENTAL HEALTH ... Modern glass fiber filters using micrometer or submicrometer fibers can achieve high efficiency with... more
... William C. Hinds* and Nani P. Kadrichu CENTER FOR OCCUPATIONAL AND ENVIRONMENTAL HEALTH, DEPARTMENT OF ENVIRONMENTAL HEALTH ... Modern glass fiber filters using micrometer or submicrometer fibers can achieve high efficiency with ac-ceptable ...