American Industrial Hygiene Association journal最新文献

Measurements of 15 nonsmokers and 3 smokers breathing environmental tobacco smoke (ETS), were conducted to study particle deposition within the human respiratory tract. The subjects inhaled ETS of count median diameter (CMD) of about 0.2 micron and geometric standard deviation (GSD) of 1.7 The particle size distribution in the submicrometer range in the inhaled and exhaled air from the subjects was measured using a scanning mobility particle sizer (SMPS). A deposition of 56.0 +/- 15.9% was observed for nonsmokers while breathing ETS through the nose and 48.7 +/- 11.6% while breathing ETS through the mouth. One individual tested four times gave an average deposition of 57.4 +/- 11.5%, providing an indication of intraindividual variation. Such a variation is expected since the breathing rate was not controlled in order that an indication of the deposition experienced on a day-to-day basis could be obtained. For nonsmokers the deposition while breathing through the mouth was lower than through the nose and the variability within the measurements was also lower for mouth breathing. The latter could be due to the variation in individual size and shape of the nasal passage. Smokers had, on average, a higher rate of deposition but also a higher interindividual variability making it difficult to draw conclusions with respect to the affect of smoking on ETS particle deposition. The average deposition of the three smokers was 65.3 +/- 24.1% for nasal breathing and 66.1 +/- 17.6% for mouth breathing.

Information provided in this article can be used for estimating the radiation dose associated with the use of thoriated tungsten electrodes in tungsten inert gas welding. Area and breathing zone concentrations of 232Th generated by welding and electrode sharpening along with particle size information; isotopic composition of electrodes from two domestic manufacturers and one European manufacturer; and process variables and estimates on the number of thoriated tungsten electrodes manufactured are presented. Past literature is reviewed and compared with the results of this study. Isotopic analysis of a nominal 2% thoriated electrode found 0.6 ppm +/- 0.4 ppm 230Th and less than 0.1 ppm 228Th. Analysis of a ceriated tungsten electrode and a lanthanated tungsten electrode for 232Th found 124 ppm and 177 ppm, respectively. Electrode consumption during welding was primarily the result of tip sharpening. Less than 3% of the weight loss was attributable to the welding process. The in-mask concentration of respirable thorium particulate in the welder's breathing zone was 0.002 x 10(-12) microCi 232Th/mL. The concentration of respirable thorium particulate from electrode sharpening was 1.3 x 10(-12) microCi 232Th/mL. The measured sharpening time was 20 sec per electrode. Estimates of the activity median aerodynamic diameters for the respirable fraction of the welding and electrode sharpening aerosols were 3.5 and 5 microns, respectively, when measured in the breathing zone at 0.3 m (12 inches) from the point of operation. The respirable fraction of the total welding and sharpening aerosols was 45 and 60%.

This article, the last in a series of three, describes the validation phase of a study conducted to test the correlation of respirator fit factors to the subject's actual exposure using biological sampling. The study consisted of three phases: protocol development, method comparison testing, and validation. Six quantitative fit-test methods were evaluated in the method comparison testing phase. The two fit methods with the highest correlation with the wearers' measured exposure were a corn oil method (R2 = 0.81) and an ambient aerosol method (R2 = 0.78). Because the ambient aerosol method is more commonly used in the workplace, it was selected for further analysis. In this validation phase, the fit factors measured during the ambient aerosol fit-test were used to calculate the exposures to Freon-113 by using the model determined in the method comparison testing phase of the study. The actual Freon-113 exposures were then measured and compared with the predicted exposures. The results verified that the ambient aerosol method fit factors are highly correlated to the total Freon-113 exposure dose and thus that the model had a predictive ability.

This study investigated arthropod and nonarthropod sources of reported bites and itching in a word processing division of a St. Louis, Mo., municipal department. Bird and rodent mites were suspected as causes of the bites because of the large population of pigeons around window ledges on some floors and the sighting of mice in the office. No mites or other arthropods were found to be responsible for the problem. Air samples were negative for fiber glass. Surface-vacuum samples collected around desks contained small quantities or traces of fiber glass or mineral wool. Humidity in the occupied space was considered low, about 35% relative humidity, with carbon dioxide measurements exceeding 1000 ppm. A single cause of the bites was not identified; however, a combination of surface-borne dust on desk tops and floors, the presence of minute quantities of mineral wool and fiber glass, relatively dry conditions, little or no outdoor air supplied to the work space, evidence of seasonally associated high work load, labor/management strife, and the presence of over 17 computers being used on a 24-hour basis (possibly leading to high levels of static electricity) were suspected as multiple causes of most of the "bites." After removal of loose mineral wool and dirt from an air handling unit and implementation of an aggressive cleaning routine, no more bites or itching were reported after a 6-month, 1- and 2-year follow-up period. Further research is needed to determine the relative importance of surface-borne dust and fibers, work stress, psychosocial support, and static electric fields, to produce bite-like sensations.

This study presents an evaluation of an adjustable keyboard based on subjective preference and wrist joint motion during typing. Thirty-five computer users used the adjustable split design keyboard for 7-14 days during their usual work and were instructed to adjust the keyboard to the opening angle they preferred. At the end of this period, three-dimensional motion analysis was performed to compare the distribution of wrist joint angles while subjects typed on a conventional keyboard and the adjustable keyboard adjusted to the subject's preferred angle. The mean preferred opening angle was 14 degrees +/- 10. The mean ulnar deviation of the subjects who selected the opening angles between 21 and 28 degrees (n = 12) decreased from 18 degrees +/- 5 on the flat to 14 degrees +/- 5 on the adjustable (p < 0.05), while those who selected 0 to 10 degrees (n = 6) and 11 to 20 degrees (n = 17) split angles showed no significant differences in ulnar deviation. Mean wrist extension on the adjustable keyboard was 17 degrees +/- 5 and was significantly less than the 24 degrees +/- 5 observed on the conventional keyboard and most likely due to the presence of palm support. On average, subjects reported that the adjustable keyboard was more comfortable (0.5 +/- 0.5) (worse = -1, same = 0, better, = 1) in comparison with the conventional keyboard.

Vibration of the seat and the body of a diesel locomotive and an electric locomotive were measured while driving on the railways of Eastern Finland. At the speed of 120 km/h for the diesel locomotive and 140 km/h for the electric locomotive (the greatest permissible speeds) the vibration of the seat was tangent to the "fatigue-decreased proficiency boundary" of the international standard ISO 2631/1(1) in the side-to-side direction in one-third octave bands of 1-1.6 Hz. The frequency response measurements between the body of the locomotive and the seat indicated that the seat did not reduce side-to-side vibration of the body at low frequencies where the vibration was most harmful.

Of the agents under consideration for protecting unoccupied areas from fire, CF3I (trifluoroiodomethane) has physicochemical properties that give it potential as a "drop-in" replacement for halon 1301. One of the issues concerning the use of CF3I is the potential hazard to ground crews should an inadvertent discharge occur while workers are in or near an engine nacelle. A discharge test of CF3I was conducted on an F-15A jet to record CF3I concentration time histories at locations near the aircraft. The conditions of the discharges simulated an inadvertent ground discharge with the engine nacelle doors open and also with the doors closed. The use of three types of gas analysis instrumentation allowed gas sampling from several locations during the discharge tests. Concentrations measured at selected sensor locations were used as the input to a physiologically based pharmacokinetic model to simulate blood levels that would be attained by individuals inhaling CF3I at sensor locations. Blood levels reached during these exposures were compared with the blood level associated with the lowest observable adverse effect level (LOAEL) for cardiac sensitization to evaluate the possibility of safe egress. The highest blood concentrations simulated were twice the target blood concentration associated with cardiac sensitization. However, simulated blood concentrations of subjects who actually inhaled CF3I reached levels that were 100 times the target level without reported adverse effect. Thus, actual human data may supersede the use of the cardiac sensitization LOAEL obtained from animal studies.

This article reports on a case of pneumoconiosis in a dental laboratory technician with a history of respiratory exposure to dental materials. Special attention is paid to the mineralogical analysis of the lung biopsy. The abundance of chromium, cobalt, and silica particles suggests that the dental technician's pneumoconiosis is the result of the combined effects of hard metal dusts and silica particles generated during finishing dental frameworks. Adequate technical protection such as a local ventilation system should be considered in dental laboratories to prevent respiratory exposure of dental technicians to airborne contaminants.