Field Evaluation of the Ultrasonic Personal Aerosol Sampler (UPAS) for Respirable Dust Exposure in a Taconite Mine.

Exposure to respirable dust (RD; the mass fraction of inhaled particles that penetrate to the unciliated airways) is a major health concern in a variety of workplaces. While the estimation of personal exposure is an essential step in protecting worker health from aerosol hazards, the traditional method for assessing personal exposure to RD, suggested by the National Institute for Occupational Safety and Health (NIOSH method 0600), requires equipment that is heavy, bulky, noisy, and has the need of frequent calibration. The ultrasonic personal aerosol sampler (UPAS) is a new personal sampling technology designed to address some of these drawbacks associated with traditional sampling methods. In this study, we field tested and evaluated the performance of the UPAS for assessing worker exposure to RD in a taconite mine. Mineworkers (n = 39) from various job categories were recruited to wear both UPAS and NIOSH 0600 samplers on a work vest to estimate time-weighted exposure to RD. A strong linear relationship was observed (NIOSH method 0600 = 1.06 (UPAS) -9.22 µg m-3, r2 of 0.72, and Pearson correlation coefficient of 0.854). None of the workers were exposed to a RD concentration above the Occupational Safety and Health Administration permissible exposure limit (5 mg m-3). A Bland-Altman analysis revealed that 72% of the valid UPAS samples agreed within ±25% of the traditional method mean. The impact of job category on the correlation of the methods was not statistically significant. This work suggests that the UPAS may present a viable alternative for assessing personal exposure to RD in the workplace.

Variability of aerosol mass and number concentrations during taconite mining operations.

This study characterized concentration metrics of airborne nanoparticles and their time series across major operations of a taconite mine through monitoring respirable and ultrafine particle concentrations at four major processing departments of the mine: crushing, dry milling, wet milling, and pelletizing (United Taconite Mine, Iron Junction, MN, USA). We used three area stations of direct-reading instruments to estimate concentration metrics including PM1 (particles with an aerodynamic diameter <1 µm), respirable dust (particles sampled according to the respirable convention with a 50% sampling efficiency at an aerodynamic diameter of 4 µm), PN (total number concentration of particles), and lung-deposited surface area concentrations (LDSA) of particles smaller than 300 nm, on two different days. Results for each station were compared using bivariate correlation analysis to obtain insight into the spatial distribution, and intra-class correlation coefficients (ICCs) to evaluate the between-day repeatability between the measurements. Comparability of the LDSA concentrations measured by two different devices was also investigated using linear regression. Results revealed that the pelletizing operation produced the highest average LDSA concentration on both days (with a maximum concentration of 199 ± 48 µm2/cm3 in pelletizing, 141 ± 52 µm2/cm3 in crushing, 91 ± 9 µm2/cm3 in dry milling, and 85 ± 7 µm2/cm3 in wet milling). Concentrations in all operations showed a fair to excellent between-day repeatability but they were significantly different within stations of each operation. Measured LDSA concentrations did not show a linear correlation between different instruments, except for crushing.

Dairy Tool Box Talks: A Comprehensive Worker Training in Dairy Farming.

Today's dairies are growing rapidly, with increasing dependence on Latino immigrant workers. This requires new educational strategies for improving milk quality and introduction to state-of-the-art dairy farming practices. It also creates knowledge gaps pertaining to the health of animals and workers, mainly due to the lack of time and language barriers. Owners, managers, and herdsmen assign training duties to more experienced employees, which may not promote "best practices" and may perpetuate bad habits. A comprehensive and periodic training program administered by qualified personnel is currently needed and will enhance the sustainability of the dairy industry. Strategic management and employee satisfaction will be achieved through proper training in the employee's language, typically Spanish. The training needs to address not only current industry standards but also social and cultural differences. An innovative training course was developed following the same structure used by the engineering and construction industries, giving farm workers basic understanding of animal care and handling, cow comfort, and personal safety. The "Dairy Tool Box Talks" program was conducted over a 10-week period with nine sessions according to farm's various employee work shifts. Bulk milk bacterial counts and somatic cell counts were used to evaluate milk quality on the three dairy farms participating in the program. "Dairy Tool Box Talks" resulted in a general sense of employee satisfaction, significant learning outcomes, and enthusiasm about the topics covered. We conclude this article by highlighting the importance of educational programs aimed at improving overall cross-cultural training.