Gunnar Rosén

Contaminant dispersion in the vicinity of a worker in a uniform velocity field

The transportation of gaseous contaminant from a low and moderate low impulse (momentum<1 m s(-1)) source to the breathing zone was studied in a uniform air stream flow. Results of the effects of the direction and the velocity of principal air flow, convection due to a human body, arm movement of a human being and the type of source on the concentration profiles are presented. Three important results were obtained. Firstly, for a given low and moderate impulse low impulse contaminant source in the near field of a worker, his/her orientation relative to the principal air flow direction is the most important factor in reducing occupational exposure, with an air velocity of about 0.3 m s(-1). Secondly, the effect of convection resulting from body heat on air flow was lower than expected. Thirdly, arm movements influence contaminant dispersion, and should be included when models assessing exposure are developed. The present data can also be used to validate existing computational fluid dynamic (CFD) models.

A method for measuring dermal exposure to multifunctional acrylates.

UV-curable acrylates are used increasingly for coating wood surfaces in the furniture industry. One of the active components, tripropylene glycol diacrylate (TPGDA), is known to be both an allergen and irritant to the skin. Methods to measure dermal exposure to skin irritants and allergens, such as acrylates, are insufficient for exposure assessment and there is none for this compound. The aim of this investigation was to develop a skin and surface sampling method, based on tape stripping, and a gas chromatographic method for quantitative analysis for assessing occupational skin exposure to multifunctional acrylates. Twelve adhesives were tested for their efficiency to remove TPGDA and UV-coating from a glass surface, the skin of guinea pigs and human volunteers employing the tape-stripping method in order to find the best performing tape. Variables that affect removal efficiency such as the applied dose and its retention time on the skin, tape adhesion time on the skin, and the number of strippings required to detect the contaminant from the skin were studied. Fixomull tape performed the best during sampling and analysis and had the most consistent removal efficiencies for the studied substances. The average removal efficiency with a single stripping at the 2 microliters TPGDA exposed skin sites was 85% (RSD = 14.1), and for UV-resin exposed sites 63% (RSD = 20.2). The results indicated that this method can be used for measuring dermal exposure to multifunctional acrylates efficiently, accurately, and economically. This method provides a sensitive and powerful tool for the assessment of dermal exposure to multifunctional acrylates both from the skin and from other contaminated surfaces in occupational field settings.

Assessment of Worker Exposure in the Processing of Ultraviolet Radiation-Cured Acrylate Lacquer-Coated Wood Products

Abstract Manufacturing of wood products coated with ultraviolet (UV) radiation-curable acrylate coatings has increased in recent years and, to our knowledge, an assessment of worker exposure has not been conducted. To assess worker exposure we identified manufacturing plants in Sweden using this technology and evaluated work force and production by questionnaire. From this database we selected eight plants that we believed were representative of the industry. At each plant, an industrial hygiene survey was conducted. Worker exposure to acrylate vapors and aerosols, dust, solvents, ozone, UV radiation (including operational performance of UV lamps), and work practices were investigated. We found that ∼350 of the 8500 production workers are potentially directly exposed to acrylates and UV radiation. Although dust levels were low (∼0.4 mg/m3, 8-hour time-weighted average), ∼30 percent of dust particles were respirable (< 5 μm diameter). Exposure to potential sensitizing agents (acrylates and photoinitiators)...

Extent of the Reverse Flow Wake Region Produced by a Body in a Uniform Flow Field

A reverse flow is created in front of an object placed in a uniform air stream that originates from behind the object. Gaseous contaminants may then be transported into the breathing zone of a worker from sources located within the reverse flow region. This should be taken into consideration when local ventilation systems are designed. The objective of this study was to characterize the reverse flow zone created in front of a worker in a uniform flow of air,using both experimental data and numerical simulation. Experiments were carried out by moving a point contaminant source on a table placed in front of the worker, and by measuring the contaminant concentration at nose level in front of the worker. The experimentally estimated length of the reverse flow region was smallest (0.5-1.0 m) with a nominal freestream velocity of 0.1 m/s, and similar (1.1-1.4 m) with nominal freestream velocities of 0.3 and 0.5 m/s.

Assessment of Ultraviolet Radiation Exposure in the Wood Surface Coating Industry

Abstract Ultraviolet (UV) radiation curing of paints and lacquers has rapidly increased in the furniture industry. Exposure to UV radiation involves a potential health hazard to workers in this industry and there is little information on UV radiation spectra and exposure levels under these working conditions. We have investigated the intensity and spectral distribution of UV radiation and determined the maximum permissible exposure times (MPETs) at different fixed points surrounding the UV curing units. The spectral irradiance was measured between 250 and 400 nm using a calibrated diode array spectrograph, and the intensity of the UV radiation was measured using a radiometer equipped with UVA and UVB detectors. The spectral power distribution was weighted for biological effect using Westers approximation equations of the spectral effectiveness curve adopted from the International Radiation Protection Association/International Non-Ionizing Radiation Committee. The intensity of the UV radiation at the subs...

A Method for Monitoring Worker Exposure to Airborne Multifunctional Acrylates

Abstract Increased use of multifunctional acrylates in surface coatings cured with ultraviolet radiation may result in increased worker exposure to airborne contaminants, but present methods are inadequate to assess the exposure levels. We have developed a method for sampling and analyzing aerosols and vapors containing multifunctional acrylates and benzophenone in order to investigate worker exposure levels. Aerosols were sorbed on glass fiber filter and vapors on tenax sorbent, desorbed with acetone, and analyzed by a gas chromatograph using a flame ionization detector and a 5 percent phenyl methyl silicone capillary column. The method was applied to the multifunctional acrylates 1,6-hexanediol diacrylate and tripropylene glycol diacrylate, as well as to the photoinitiator benzophenone. The parameters investigated were recovery (85%), precision (<5%), storage stability (20 days at 4°C), and detection limits. Concentrations as low as 2 μg/m3 for multifunctional acrylates and 1 μg/m3 for benzophenone can ...

Surface Contamination to UV-Curable Acrylates in the Furniture and Parquet Industry

Surface contamination to ultraviolet radiation curable coatings (UV coatings), used increasingly in the parquet and furniture industry, is a matter of concern as a source for skin contamination. UV coatings contain chemically and biologically reactive acrylates, well known as skin contact irritants and sensitizers. Surface contamination may spread secondarily to equipment and other unexpected areas even outside the workplace. Yet, studies concerning this type of contamination are lacking due to lack of suitable sampling methods. Surface contamination of the work environment with risk for skin exposure to UV coating was measured employing a quantitative adhesive tape sampling method developed for this purpose. A pilot study was first performed at three workplaces to evaluate the contamination. In the main study, we wanted to locate and identify in detail the surface contamination of areas where problems exist, and to determine the extent of the problem. Measurements were performed at seven workplaces on two separate workdays (round 1 and 2) within a six-month period. Samples were collected from the workplaces based on the video monitoring of skin contact frequency with the surfaces and categorized into three groups to analyze risk. The pilot study indicated that surface contamination to TPGDA containing UV coatings was common, found in 76 percent of the surfaces, and varied with a maximum of 909 microg TPGDA 10 cm(-2) sampling area. In the main study TPGDA was found in 153 out of 196 collected samples (78.1%); for round one 78.1 percent (82 out of 105 samples) and for round two 78.0 percent (71 out of 91 samples). The average TPGDA mass on positive surface samples was on the first round 2,247 +/- 7,462 microg, and on the second round 2,960 +/- 4,590 microg. We conclude that surface contamination to uncured UV coatings at UV-curing lines is common and this involves a risk for harmful, unintentional skin exposure to acrylates.

Research Note: Video exposure monitoring for transfer of knowledge in chemical hazards to small enterprises

Abstract Despite the development of effective control technology, occupational exposure to silica and wood dust is a significant important problem for many small enterprises in wood working and quarrying industries. Tens of millions of workers’ occupations involve hazardous silica dust exposure and within the European Union alone, about 3.6 million workers are exposed to inhalable wood dust. The present study used the visualisation method PIMEX for transfer of knowledge in how health risks may be reduced. Typical work situations observed to cause high dust exposures were recorded. The results demonstrate that appropriate use of generally available technology and knowledge can significantly reduce worker exposure. The PIMEX-video monitoring method is a useful tool in knowledge transfer and also is seen to improve worker’s as well as manager’s motivation to use available knowledge. Case studies of the application of the technology have been made available on Internet. Visualised presentations using the PIMEX recordings are seen to be more effective compared to the more traditional training materials.

10 – LOCAL VENTILATION

This chapter describes the aerodynamic principles, models, and equations that govern the flow and the contaminant presence and transport in a designated volume of a workroom. Local ventilation is often a very important part of the ventilation system, both in function and in construction. By using a local ventilation system of good design less air is needed to reach a specific contaminant level than is possible with general ventilation. Proper design and construction of a local ventilation system must account for hood flow rate, contaminant generation process and rate, and the generated flow rate of contaminated air. Thus, knowledge about airflow mechanics, process performance, and the contaminant source is essential. The purpose of local ventilation is to control the transport of contaminants at or near the source of emission, thus minimizing the contaminants in the workplace air. All local ventilation systems can, in principle, be manufactured for use in one or more of three different modes: fixed, flexible, and mobile.

Short-term Variation in Occupational Exposure to Air Contaminants

Many industrial workers are exposed to air contaminants. A significant proportion of this exposure is found to occur as short peaks, a fact that has received limited attention in the literature. The present study focuses on short-term variation in air contaminant exposure measured at the level of seconds, linking exposure peaks to typical work situations in selected Swedish industries. The video exposure monitoring method was used to characterize this variation. Ten different videos were analyzed, from recordings varying in length between 15 and 34 minutes. Cumulative exposure for sampling intervals ranked from high to low, relative to the total exposure was calculated as a function of time. Measures of exposure variation included geometric standard deviation and maximum exposure divided by arithmetic mean. The results show that the characteristics of the variation differ between industrial situations. Samples from the stone, wood, and pharmaceutical industries generated the highest variation, implying that exposure peaks of short duration explain a large proportion of the total exposure. It can be concluded that video monitoring of exposure, combined with calculation of exposure variation as percentage of time accounting for given percentages of exposure, can help to reduce exposure to air contaminants in industrial situations by introducing more targeted control measures.