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James H Vincent

Publications and source records attributed to James H Vincent.

12 recordsLinked to original sources
PubMed2005

Testing personal inhalable aerosol samplers: a suggested improved protocol based on new scientific knowledge.

In 2002 the Comité Européen Normalisation (CEN) published its document Workplace atmospheres-assessment of performance of instruments for measurement of airborne particle concentrations (EN 13205) that describes a standard protocol by which to carry out the testing and validation of personal aerosol samplers of the type widely used for occupational aerosol exposure assessment. It emerged from more than a decade of discussion and a large body of research experience involving several laboratories. The protocol that is described, however, still poses significant technical and economic challenges, not least because it involves laborious-and hence costly-procedures in large, specialized wind tunnel facilities. More recent research has identified a number of areas by which the protocol may be improved and made more accessible to testing laboratories, including a set of validated aerosol sampler scaling laws, a better understanding of the reduced role of the bluff body of the wearer on sampler performance, and the availability of new options for rapid sampler testing methods. Taking these into account, a dummy new protocol is offered for discussion.

Aerosols↗
PubMed2005

Health-related aerosol measurement: a review of existing sampling criteria and proposals for new ones.

Interest in particle size-selective sampling for aerosols in working and ambient living environments began in the early 1900s when it became apparent that the penetration into-and deposition in-the respiratory tract of aerosol-exposed humans of inhaled particles was dependent on particle size. Coarse particles tended to be filtered out during inhalation and in the upper parts of the respiratory tract, so only progressively smaller particles penetrated down to the deep regions of the lung. Over time, following experimental studies with 'breathing' mannequins in wind tunnels and with human volunteer subjects in the laboratory, a clear picture has emerged of the physical, physiological and anatomical factors that control the extent to which particles may or may not reach certain parts of the respiratory tract. Such understanding has increasingly been the subject of discussions about aerosol standards, in particular the criteria by which exposure might be defined in relation to given classes of aerosol-related health effect-and in to turn aerosol monitoring. The ultimate goal has been to develop a set of criteria by which exposure standards are scientifically relevant to the health effects in question. This paper reviews the scientific basis for such criteria. It discusses the criteria that have already been widely discussed and so are either being applied or are on the threshold of practical application in standards. It also discusses how new advanced knowledge may allow us to extend the list of particle size-selective criteria to fractions that have not yet been widely discussed but which may be of importance in the future.

Aerosols↗
PubMed2005

Graduate education in occupational hygiene: a rational framework.

Occupational hygiene has been an important part of occupational health since it first emerged after World War II as the science and art that deals with the anticipation, recognition, evaluation and control of human exposures to hazards in the working environment. A need exists for well-qualified professionals who can not only respond to hazards that are currently known and understood, but also to ones that are not yet known or understood. For this, graduate-level academic programs in occupational hygiene must go beyond the training of skills and imparting of facts. Rather they must provide the education that enables the development of critical faculties, allowing future self-learning and the study of new scenarios not yet anticipated. Ideally, occupational hygiene should be taught firstly in the interdisciplinary context of the whole of occupational health (including occupational medicine, occupational health nursing, occupational safety and ergonomics) and secondly in relation to the wider field of public health (including epidemiology and biostatistics). In addition, modern occupational hygiene education also needs to embrace the management and social sciences. The Education and Research Centers (ERCs) sponsored in the United States by the National Institute of Occupational Health (NIOSH) have refined this approach and provided a useful model for all occupational hygiene education, identifying the need for both masters and doctoral-level endeavor. Other countries might usefully consider integrating existing academic programs in order to emulate the NIOSH approach, perhaps through internal and external partnerships. In terms of content, such education needs to be carried out within a framework that places human exposure to hazardous agents at the center of the anticipation-recognition-evaluation-control rationale. Such a framework also places occupational hygiene in the context of the other occupational and environmental health disciplines. Finally it has to be acknowledged that occupational hygiene is (indeed always was) a changing field. Academic programs need to be responsive to such changes, and the range of responses must include not only curricular modifications but also changes in the way that the education itself is delivered. The internet provides interesting new opportunities for distance learning that appear to have the potential not only to be efficient and convenient in terms of time and resources but also to be valid in terms of meeting the desired educational objectives.

Education, Medical, Graduate↗
PubMed2005

Environmental health implications of global climate change.

This paper reviews the background that has led to the now almost-universally held opinion in the scientific community that global climate change is occurring and is inescapably linked with anthropogenic activity. The potential implications to human health are considerable and very diverse. These include, for example, the increased direct impacts of heat and of rises in sea level, exacerbated air and water-borne harmful agents, and--associated with all the preceding--the emergence of environmental refugees. Vector-borne diseases, in particular those associated with blood-sucking arthropods such as mosquitoes, may be significantly impacted, including redistribution of some of those diseases to areas not previously affected. Responses to possible impending environmental and public health crises must involve political and socio-economic considerations, adding even greater complexity to what is already a difficult challenge. In some areas, adjustments to national and international public health practices and policies may be effective, at least in the short and medium terms. But in others, more drastic measures will be required. Environmental monitoring, in its widest sense, will play a significant role in the future management of the problem.

Climate↗
PubMed2004

An exploratory study of changing occupational injury risk during the closure of industrial operations.

Companies go out of business on a regular basis, and industrial plants close as a result. Various social, economic and interpersonal dynamics accompany such events. Environmental health and safety (EH&S) aspects are not exempt from those dynamics during a programmed closing of a manufacturing operation. How does this condition fit the industrial hygiene paradigm of anticipation, recognition, evaluation and control? This paper describes an exploratory enquiry into the nature of risk to human health and safety associated with the planned closure of a manufacturing operation. As a starting point, the recognition of risk was explored using a qualitative opinion survey of a group of independent EH&S professionals. The survey, reflecting what is often referred to as the 'art' of industrial hygiene, gathered professional impressions of change in potential risk of injury during a hypothetical plant-closing. The results suggested that a plant-closing might be considered a real issue by most EH&S professionals, and pointed specifically to management of personnel behavior, employee satisfaction and outside influences as primary potential sources of increased risk of injury during this final phase of a plant's life. Next, a specific real-world example was considered to evaluate actual change in injury statistics. For this, compensation claim records were examined for a malt beverage manufacturer before and after an official announcement of closure for four geographically distinct North American plants. Risk was evaluated first in terms of the one-monthly and three-monthly rates of injury incidence and then in terms of severity (expressed as cost), based on data derived from compensation claim records as of the month of plant closing. The rate of injury incidence appeared to have increased during plant-closing for one of the plants, but the results were equivocal for the other three plants. On the other hand, when the results were transformed so that the injury incidences were weighted with respect to the cost, the effective impact on the injury rate appeared to increase for three of the plants. Most importantly overall, this paper identifies-for the first time-that there is the potential for increased injury risk during a plant closure phase, and so poses an alert for EH&S professionals and management to implement possible preventative control options in such situations.

Accidents, Occupational↗
PubMed2004

The orientation-averaged aspiration efficiency of IOM-like personal aerosol samplers mounted on bluff bodies.

This paper describes two sets of experiments that were intended to characterize the orientation-averaged aspiration efficiencies of IOM samplers mounted on rotating bluff bodies. IOM samplers were mounted on simplified, three-dimensional rectangular bluff bodies that were rotated horizontally at a constant rate. Orientation-averaged aspiration efficiencies (A360) were measured as a function of Stokes' number (St), velocity ratio (R) and dimension ratio (r). Aspiration efficiency (A) is the efficiency with which particles are transported from the ambient air into the body of a sampler, and A360 is A averaged over all orientations to the wind. St is a dimensionless variable that represents particle inertia, R is the ratio of the air velocity in the freestream and that at the plane of the sampler's entry orifice, and r is the ratio of the sampler's orifice diameter and the bluff body's width. The first set of experiments were instrumental in establishing a hierarchy of effects on orientation-averaged A. It was clear that compared to r, St had a much larger influence on A. It was also clear, however, that the effects of St were overpowered by the effects of R in many cases. As concluded in previous studies, R and St were considered the most important factors in determining A, even for A360. The second set of experiments investigated A360 of IOM samplers for a much wider range of r than examined in previous research. Two important observations were made from the experimental results. One was that the A360 of IOM samplers, as a function of St, did not change for an r-range of 0.066-0.4. This meant that an IOM sampler mounted on a near life-size mannequin would measure the same aerosol concentration as one not mounted on anything. The second observation was that the aspiration efficiency curve of the IOM sampler was close to the inhalability curve. This gave further evidence that the bluff body did not play a major role in influencing A360, as the IOM samplers, in these experiments, were either mounted on miniature bluff bodies or on nothing at all. These observations all suggest that it is quite possible to design and test personal samplers with desired sampling characteristics using protocols that do not require full-size mannequins, which greatly simplifies the development of new samplers.

Aerosols↗
PubMed2003

Critical evaluation of historical occupational aerosol exposure records: applications to nickel and lead.

Published or unpublished data sets on individual occupational exposure situations are frequently combined and used for some wider purpose, either hazard evaluation or standards setting. This paper describes a model by which such individual data sets for occupational aerosol exposures might be evaluated in terms of their usefulness in this regard. For workplace aerosols, the model is centered around the particle size-selective framework for aerosol exposure assessment that has emerged in recent years as a rational basis for standards setting. In this paper, reported occupational exposures to airborne nickel and lead are used as examples. In a comprehensive review, 106 published peer-reviewed sources of potentially useful exposure data were found for nickel and 111 similar reports for lead. In addition, for lead 116 unpublished reports in the form of hazard evaluation reports from the US National Institute for Occupational Safety and Health were also examined. For both nickel and lead, a wide range of industry sectors was represented, and the data sets cover the period from 1930 to the present day. It was found that such published data sets are highly inconsistent in terms of the criteria by which the data were obtained, notably for the paucity of essential details of the methods that were used. In contrast, for the lead exposures, the unpublished government reports are more consistent, since they usually followed recognized exposure assessment standards. However, the latter may be misleading because they may have tended to represent high exposure situations. The evaluation model described in this paper provides not only a basis for the evaluation of historical exposure data but also guidelines for new exposure assessment to be carried out in the future. Meanwhile, although many of the historical exposure data sets were found to be generally quite weak in terms of their immediate usefulness, attention is drawn to some of their statistical properties that might allow their enhancement for the purposes of hazard evaluation and retrospective exposure assessment exercises.

Aerosols↗
PubMed2003

Expert judgment and occupational hygiene: application to aerosol speciation in the nickel primary production industry.

In many situations characterized by sparse data, occupational hygienists have used subjective judgments that are claimed to be derived from their experience and knowledge. While this practice is widespread, there has been no systematic study of 'expert judgment' or the 'art' of occupational hygiene. Indeed, there is a need to address the question of whether there is such a thing as 'expert opinion' in occupational hygiene that is broadly shared by practicing professionals. This research, employing 11 experts who estimate an exposure parameter (the percentages of four nickel species) in 12 workplaces in a nickel primary production industry, provides a large dataset from which useful inferences can be drawn about the quality of expert judgments and the variability among the experts. A well-designed questionnaire that provided succinct information about the processes and baseline data served to calibrate the experts. The Bayesian framework has been used in this work to develop posterior means and standard deviations of the percentages of the four nickel species in the 12 workplaces of interest in the company. These estimates of the nickel speciation are at least as precise as--and most of the time more precise than--those provided by the sparse measurement data. There was a very high degree of agreement among the experts. A majority of the experts agreed among themselves 92% of the time, while almost two-thirds agreed 73% of the time. This, coupled with the fact that the experts came from varied backgrounds, seems to suggest that there is indeed some broad body of specialized knowledge that the experts are drawing on to reach similar judgments. It also seems that one type of expert is not necessarily any better than any other kind, and expertise does not necessarily require intimate familiarity with the workplace. In this example, the expert judgment exercise has indeed enhanced the quality of our knowledge of the exposure 'fingerprints' for the nickel industry workplaces studied and the combination of expert judgment and sparse data is better than the sparse data alone. For occupational hygiene exposure assessment, our experience suggests that such expert judgment methods can provide a cost-effective means to improve and refine information about workplace hazards. However, more study is warranted for situations where the domain of the quantity of interest has a much wider range of values, e.g. actual exposure values.

Air Pollutants, Occupational↗
PubMed2002

New experimental methods for the development and evaluation of aerosol samplers.

An understanding of the scaling laws governing aerosol sampler performance leads to new options for testing aerosol samplers at small scale in a small laboratory wind tunnel. Two methods are described in this paper. The first involves an extension of what is referred to as the "conventional" approach, in which scaled aerosol sampler systems are tested in a small wind tunnel while exposed to relatively monodisperse aerosols. Such aerosols are collected by test and reference samplers respectively and assessed gravimetrically. The new studies were carried out for a modified, low flowrate version of the IOM personal inhalable aerosol sampler. It was shown that such experiments can be carried out with a very high level of repeatability, and this supported the general validity of the aerosol sampler scaling laws. The second method involves a novel testing system and protocol for evaluating the performances of aerosol samplers. Here, scaled aerosol samplers of interest are exposed to polydisperse aerosols, again in a small wind tunnel. In this instance, the sampled particles are counted and sized using a direct-reading aerodynamic particle sizer (the APS). A prototype automated aerosol sampler testing system based on this approach was built and evaluated in preliminary experiments to determine the performance of another modified version of the IOM personal inhalable aerosol sampler. The design of the new test system accounts for the complex fluid mechanical coupling that occurs near the sampler inlet involving the transition between the external flow outside the sampler and the internal airflow inside the sampler, leading in turn to uncontrolled particle losses. The problem was overcome by the insertion of porous plastic foam plugs. where the penetration characteristics are well understood, into the entries of both the test and the reference samplers. Preliminary experiments with this new system also supported the general validity of the aerosol sampler scaling laws. In addition, they demonstrated high potential that this approach may be applied in a standardised aerosol testing method and protocol.

Aerosols↗
PubMed2002

Personal sampling for inhalable aerosol exposures of carbon black manufacturing industry workers.

The study was concerned with the measurement of inhalable aerosol exposures in the carbon black production industry. The primary goal of the study was to determine the extent to which inhalable aerosol exposure, as measured by the Institute of Occupational Medicine (IOM) personal inhalable sampling head, compared to "total" aerosol exposure, as measured by traditional methodology. A secondary objective was the evaluation of another inhalable aerosol sampler for carbon black aerosol measurement. In addition, an exploratory evaluation of the applicability of the National Institute for Occupational Safety and Health (NIOSH) analytical method (Method 5040) for the determination of carbon black, measured as elemental carbon, was conducted. A field study was carried out in a number of North American carbon black production plants using three samplers: the 2 Lpm IOM sampler as a reference sampler for the inhalable fraction, the 2 Lpm closed-face 37-mm plastic cassette that has been used for many years for total aerosol, and the 3.5 Lpm GSP sampler that has recently been identified by some as a possible candidate for inhalable aerosol. No such studies have previously been reported for the carbon black industry. Further, there have been no reports of the GSP performance in direct comparison to a reference instrument like the IOM sampler. The results showed that inhalable aerosol exposures for workers in carbon black production and packing areas were higher than the corresponding total aerosol exposures by a factor of nearly three, implying the presence of significantly coarser aerosol than previously thought based simply on knowledge of the carbon black production process. The fact that the aerosols collected in portions of the process comprised high proportions of non-elemental carbon particulate was thought likely to be responsible, underlining the need to consider whether gravimetric assessment for such exposure is the most appropriate metric. In addition, and somewhat surprisingly, the GSP sampler emerged clearly as a good alternative to the IOM sampler for collecting inhalable aerosol in carbon black industry workplaces like those studied (although this conclusion cannot yet be extended to other workplaces).

Aerosols↗
PubMedDate not supplied

Filter and cassette mass instability in ascertaining the limit of detection of inhalable airborne particulates.

In the gravimetric assessment of workplace aerosols, there is an increasing need to confidently measure smaller and smaller collected masses. To do this, it is important to know both the limit of detection (LOD) and limit of quantification (LOQ) of the analysis performed, determined by the weighing imprecision of blank samples. Of particular current interest is the measurement of inhalable aerosols, as defined for many substances in the American Conference of Governmental Industrial Hygienists threshold limit values list. One popular method is the use of a filter contained within a small cassette, in which both are weighed. Earlier investigations of plastic and stainless steel cassettes showed that plastic cassettes are highly sensitive to changes in humidity. But one study also demonstrated that the resulting changes in mass could be largely corrected using field blanks. An investigation, therefore, was undertaken to determine the weighing imprecision of various cassette and filter assemblies, assuming blank corrections are made. Three types of filter (Teflon, glass fiber, and polyvinyl chloride) were investigated in combination with three types of cassette (plastic, nickel-plated plastic, and stainless steel). Results show that regardless of the substrate being used, sample masses equal to or higher than 0.19 and 0.65 mg can be confidently detected and quantified, respectively.

Air Pollutants, Occupational↗