Benefits and limitations of field-based monitoring approaches for respirable dust and crystalline silica applied in a sandstone quarry

With the advent of new sensing technologies and robust field-deployable analyzers, monitoring approaches can now generate valuable hazard information directly in the workplace. This is the case for monitoring respirable dust and respirable crystalline silica concentration levels. Estimating the quartz amount of a respirable dust sample by nondestructive analysis can be carried out using portable Fourier transform infrared spectroscopy (FTIR) units. Real-time respirable dust monitors, combined with small video cameras, allow advanced assessments using the Helmet-CAM methodology. These two field-based monitoring approaches, developed by the National Institute for Occupational Safety and Health (NIOSH), have been trialed in a sandstone quarry. Twenty-six Helmet-CAM sessions were conducted, and forty-one dust samples were collected around the quarry and analyzed on-site during two events. The generated data generated were used to characterize concentration levels for the monitored areas and workers, to identify good practices, and to illustrate activities that could be improved with additional engineered control technologies. Laboratory analysis of the collected samples complemented the field finding and provided an assessment of the performance of the field-based techniques. Only a fraction of the real-time respirable dust monitoring sessions data could be corrected with laboratory analysis. The average correction factor ratio was 5.0. Nevertheless, Helmet-CAM results provided valuable information for each session. The field-based quartz monitoring approach overestimated the concentration by a factor of 1.8, but it successfully assessed the quartz concentration trends in the quarry. The data collected could be used for the determination of a quarry calibration factor for future events. The quartz content in the dust was found to vary from 14% to 100%, and this indicates the need for multiple techniques in the characterization of respirable dust and quartz concentration and exposure. Overall, this study reports the importance of the adoption of field-based monitoring techniques when combined with a proper understanding and knowledge of the capabilities and limitations of each technique.

[Occupational health risk assessment of pneumoconiosis caused by dust exposure at 18 quarries in a given area of Hubei Province]

OBJECTIVE

To explore the occupational health risk level of pneumoconiosis caused by dust exposure in a given area of Hubei province.

METHODS

From April 2021 to October 2021, 18 quarries were randomly selected in the areas where quarries were concentrated in Hubei Province to conduct on-site hygiene investigation and detection. A total of 384 workers were employed in the above quarries, and 293 workers were exposed to dust. The International Mining and Metals Commission's risk rating table method and occupational hazard risk index method were used to analyze the occupational health risk level from total and respirable dust views, respectively. Meanwhile, the square weighted Kappa test was performed to analyze the consistency between two risk assessment method.

RESULTS

The median dust exposure rate of workers in the above18 enterprises was 73.22%, small, underground mining, and barite quarries had relatively higher dust exposure rates(all median were 100.00%). The medians of daily dust exposure time, personal protective equipment wearing rate, free silica content of dust, 8-hour time weighted average exposure concentration of total dust and respirable dust in each assessment indicator were 6-8 hours, 0%-24.00%, 1.69%-35.30%, 0.56-3.70 mg/m~3, and 0.33-1.20 mg/m~3, respectively. Occupational health risk assessment result showed the overall occupational health risk levels of quarries, as well as different production scales and mining method, were all low. Among different positions, wind driller and tunneling worker had high and medium occupational health risk, respectively, and the rest of the positions had low or very low risk. International Council on Mining and Mentals(ICMM) risk rating table method and the INDEX method consistency analyses showed that these two risk assessment method had strong consistency in terms of total dust(Kappa value was 0.65(95%CI 0.57-0.73)), and general consistency in term of respirable dust(Kappa value was 0.51(95%CI 0.39-0.62)).

CONCLUSION

The overall occupational health risk level of pneumoconiosis caused by dust exposure in quarries was low, but risk levels were higher for wind driller and tunneling worker.

A UAV-Based Air Quality Evaluation Method for Determining Fugitive Emissions from a Quarry during the Railroad Life Cycle

Gravel is used in railway infrastructure to reduce environmental impacts and noise, but gravel on tracks must be replaced continuously because it deforms due to wear and weathering. It is therefore necessary to review the entire railroad life cycle. In this study, an unmanned aerial vehicle (UAV) was used to measure resuspended dust over a wide area. The dust was generated from transport movements in relation to the operation of a quarry, which represents the first stage of the railway life cycle. The dust was measured at Gangwon-do quarry using a Sniffer4D module, which can provide measurements at 1 s intervals through a light scattering method and has high reliability (R² = 0.95 for PM_2.5, R² = 0.88 for PM₁₀). The hourly generation of fugitive dust was calculated as 2937.5 g/h for PM_2.5 and 4293.2 g/h for PM₁₀. The social cost of dust generation was calculated as KRW 36.59 billion. The amount of dust generated per hour at the quarry was ~12 times greater than that generated by the operation of a regulator as a maintenance vehicle, with the largest amount of fugitive dust generated by the washing-type vehicle. This is the first study to measure the amount of fugitive dust generated in real time at 1 s intervals by monitoring the first stage of the railroad life cycle over a wide area using a Sniffer4D module attached to a UAV. This method can be replicated for use in various studies.

Tower of Belém (Lisbon)-Status Quo 3D Documentation and Material Origin Determination

The Tower of Belém, an early 16th century defense tower located at the mouth of the Tagus river, is the iconic symbol of Lisbon. It belongs to the Belém complex, classified since 1983 as a World Heritage Site by the UNESCO, and it is the second most visited monument in Portugal. On November 1st, 1755, there was a heavy earthquake in Lisbon followed by a tsunami, causing between 60,000 and 100,000 deaths. There is a possibility of a repetition of such a catastrophe, which could bring about the collapse of the structure. This was the reasoning behind the decision to evaluate the Tower of Belém by means of surveys using Terrestrial Laser Scanning and photogrammetry. Until now, there was no high-resolution 3D model of the interior and exterior of the tower. A complete 3D documentation of the state of the Tower was achieved with a cloud of more than 6,200 million 3D points in the ETRS89 PT-TM06 coordinate system. Additionally, measurements were made using a hyperspectral camera and a spectroradiometer to characterize the stone material used in the Tower. The result is a digital 3D representation of the Tower of Belém, and the identification of the quarries that may have been used to extract its stone. The work carried out combines geometrical and material analysis. The methods used may constitute a guide when documenting and intervening in similar heritage elements. Finally, the information contained therein will allow an eventual reconstruction of the Tower in the case of another catastrophe.

Prostate-specific antigen and its derivatives in young adults occupationally exposed to quarry pollutants in southeastern Nigeria

To evaluate the level of total prostate-specific antigen (PSA) and effect of duration of exposure to pollutants in quarry workers, 5 mls of blood sample was collected from participants: 72 male quarry workers exposed to quarry pollutants and 72 unexposed controls. PSA estimations were done using the principle of ELISA. Mean total PSA, free PSA, and free-total PSA ratio levels of quarry workers did not differ from those of controls and was below the cutoff for the risk of prostate diseases. Higher mean total PSA and free PSA were observed in workers exposed for > 3 years compared to the unexposed control and workers exposed for ≤ 3 years. Age-adjusted linear regression indicated significant association (R = 0.515; p < .001) between the duration of exposure and total PSA level in quarry workers. This study suggests that longer duration of exposure to the quarry pollutants may elevate PSA level if precautions are not taken to minimize dose of exposure.

Comparison of pulmonary function test abnormalities between stone crushing dust exposed and nonexposed agricultural workers

OBJECTIVES

The aim of this study is to examine the effects of stone crushing in West Bengal, India, by comparing pulmonary functions of stone crushing workers with those of nonexposed agricultural workers.

METHODS

Two hundred seventy two stone crushing workers and 123 nonexposed workers were analyzed in terms of occupational and personal histories, radiological findings, and pulmonary function test (PFT) results including slow vital capacity (FVC), forced vital capacity (FVC) and peak expiratory flow rate (PEFR). Different lung volumes i.e. FEV(1), FEV(1%), and flow rates i.e. FEF(200-1200ml), FEF(25-75%) and FEF(75-85%), were analyzed with regard to sex, smoking habit, work status, age and work duration.

RESULTS

Contrary to our expectations, the incidences of suspected (2.94%) and definite (1.84%) pneumoconioses were very low and the results of some PFT such as those for FVC and FEV(1%), in the exposed group were better than those in the nonexposed group, although a gradual decline the performance in PFT was observed with age and work duration. There was a higher prevalence of restrictive impairment among the exposed group and a higher prevalence of obstructive impairment in the nonexposed group.

CONCLUSIONS

Some of the results were unexpected. Possible reasons for these include (i) undetectable concentrations of free silica in the stone dust in the work environment of the exposed workers and (ii) factors, such as climate, in the work environment of the nonexposed agricultural workers that could cause pulmonary impairment. Further protective measures should be undertaken to prevent pulmonary impairment in both groups of workers.