Empowering Your Projects with Innovative, Crystalline ...
Empowering Your Projects with Innovative, Crystalline ...
Decorative Surfaces Reimagined
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Our new Zenith Surfaces range doesn&#;t just transform the world of surfaces&#;it sets a global benchmark for sustainable design. Launching as a replacement for our Stone Ambassador Engineered Stone collection, this innovative product responds directly to the Australian government&#;s groundbreaking ban on engineered stone products containing more than 1% crystalline silica. Implemented in July, this decisive measure aims to prevent silicosis, a debilitating lung disease linked to silica dust exposure, particularly affecting stonemasons and construction workers.
Pioneering Change
While some manufacturers viewed the ban as a termination point, Stone Ambassador embraced it as a pivotal opportunity for design evolution. This significant shift allows us to lead the industry forward through pioneering material innovation. Our unwavering commitment to worker health and safety establishes a new industry standard.
However, the innovation of Zenith Surfaces goes beyond its silica-free composition. This remarkable product achieves a crucial balance: a safe, compliant material that does not sacrifice the aesthetics or performance demanded by architects and designers. By replacing quartz with recycled glass, we&#;ve managed to retain the look, feel, durability, and performance that industry professionals have come to rely on.
Sustainability Meets Imagination
Zenith Surfaces features 40 available meticulously curated patterns across five unique ranges. Zenith Surfaces draws inspiration from nature&#;s raw beauty, offering a palette of luxurious marble-look designs, soft-touch matte surfaces, and organic colours, encapsulating the elegance of intricate patterns and breathtaking visuals.
The non-porous, durable, and resistant nature of these surfaces enhances their appeal, providing a hygienic and easy-to-clean solution that resists bacteria and mold. Coupled with Zenith Surfaces&#; sustainable composition, crystalline silica-free formula, and a market-leading 10-year warranty, this collection emerges as the ultimate choice for design professionals aiming to create exquisite kitchens, bathrooms, bars, and more.
Zenith Surfaces represents more than mere compliance. This groundbreaking product epitomises our commitment to innovation, worker safety, design excellence, and environmental stewardship. It&#;s not just a design tool&#;it&#;s a catalyst for transformative change in the Australian design landscape. By choosing Zenith Surfaces, design professionals are making a powerful statement for a safer, more sustainable future for all.
Experience the Future of Surface Design
We invite you to visit one of our five national showrooms or order your free sample sets to witness our commitment to safe, sustainable surface designs.
Discover how Zenith Surfaces can transform your home&#;&#;.
From Engineered Stone Slab to Silicosis
Once large stone slabs are manufactured, they are transported to local stone workshops where they are further processed into bespoke designs to meet customer demands [22]. Typically, ES processing involves the use of power tools to cut, drill, grind and shape the stone slab into benchtops. These are then polished and laminated to achieve the final product [23]. Some of these tasks are carried out semi- or wholly-automated and in enclosed conditions, e.g., cutting using waterjet cutting or computer numerical control (CNC) machines, while tasks like polishing are often carried out manually using pneumatic hand-held power tools. However, smaller workshops can often have more tasks carried out manually [23], likely due to the lack of infrastructure required for automation. Most of these tools are operated under wet conditions, using recycled water systems ranging from commercial filtration set-ups to in-house settling tanks to feed on to semi-automated and automated tools. Hand-held tools such as pneumatic grinders and polishers are typically centrally water-fed through hose attachments. After benchtops are cut and polished in stonemasonry workshops, they are transported to customers&#; premises for onsite installation, where finishing touches such as smoothing of edges or holes are performed using hand-held tools such as angle grinders&#;which is often a dry process [24].
Benchtop making can be a dynamic process, involving a variety of tasks including cutting, shaping, set-up time and moving slabs during a work shift [25]. As such, there may be multiple workers doing different tasks contributing to the dust atmosphere in the workplace. This represents a challenge for accurate exposure assessments to determine the most at-risk tasks in the workplace and such situations may concomitantly place place at risk workers not actively generating dust. It is also noteworthy that while uncontrolled (i.e., dry) processing of ES is not permitted by many countries, including Australia, workers still resort to brief dry methods for specific operations, for example during benchtop installations, as described earlier [5,23,25]. Brief dry processing ES can cause extremely high levels of exposures to RCS [26].
It is noteworthy that natural stones contain much higher levels of metals, compared to ES. We showed that natural stones such as granite and marble contain metals between 29 and 37% by weight of their total composition. White granite and marble contain predominantly alkaline metals such as Ca, Mg and Al while black granite shows more variation in its metallic elements, including transition elements such as Ti and Fe [ 6 ].
Among the inorganic constituents of ES are metal elements, originating most likely from pigments that are added during ES manufacture [ 33 ]. Studies have reported between 11 and 17 metals in variable amounts in ES dust samples [ 8 , 10 , 29 ]. Among the most common and abundant metals (>1 g/kg) are Al, Na, Fe, Ca, and Ti. Tungsten (W) has also been reported to be a major component of ES, although it cannot be verified whether this is intrinsic to ES or an artefact as a result of contamination from the blade used for cutting (steel and carbide bits) [ 10 ]. Other elements such as Co, Cu, Ni, Zn and Ba have been identified in concentrations ranging from 3 to 312 mg/kg, while more toxic metals such as As, Cd and Pb are typically <0.2 mg/kg (except Pb which ranged from 0.53&#;409 mg/kg) [ 10 ].
Most studies reporting ES-associated VOCs have reported semi-quantitative data under laboratory test conditions, which therefore cannot be directly related to worker exposure to VOCs during fabrication tasks. Reed et al. () [ 32 ] were among the few ones to report onreal-world full-shift occupational exposure monitoring of VOCs during ES manufacture. Similar to laboratory studies, they reported a variety of VOCs, including styrene and other &#;aliphatic and aromatic hydrocarbons, ketones and alcohols emitted from thinners/solvents, glues/adhesives, resins and other industrial chemicals used on the premise&#;, that ES workers may be exposed to during stone benchtop manufacture [ 32 ]. The processing of ES often entails workers complaining of smells, attributable to the breakdown of resin. However, Reed et al. () [ 32 ] did not report exposures above the workplace exposure standards.
Many ES, either &#;traditional&#; high-Si ES or new-generation reduced-Si ES, contain on average 5&#;15% by weight resin [ 8 , 30 ]. Processing these resin-based ES generates a suite of VOCs, many of which have been independently linked to adverse lung health outcomes in the literature. One of the most common VOC identified from ES processing is styrene [ 7 , 10 ], which has important health implications as occupational exposure to styrene has been directly linked to pulmonary toxicity [ 31 ]. Other commonly found VOCs are toluene, benzene, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and respiratory sensitisers such as phthalic anhydride [ 8 , 10 , 11 ].
ES particles generated by either wet or dry processing have conchoidal fractures, sharp edges and irregular shapes, characteristic of fractured pure quartz crystals. ES particles also show aggregation, whereby small particles stick to the surface of larger ones, potentially by static charges, as shown on images generated using scanning electron microscopy by Pavan et al. () [ 29 ] and Ramkissoon et al. () [ 6 ]. In comparison, it has been observed that NS particles generated in a similar way as ES exhibited less fractures at the surface, or sharp edges, and are more &#;layered&#; structures [ 6 ].
ES processing generally generates small particles, with many studies reporting that >90% of the airborne particle mass is in the respirable fraction (4 µm mass median aerodynamic diameter) [ 6 , 29 ] with some mass even in the nanometre range (<100 nm in aerodynamic diameter) [ 28 ]. Fabrication tasks influence the size of the emitted particles. During cutting, a higher amount of airborne dust is produced compared to when stones are polished; during polishing, the size distribution of the particles is smaller and narrower [ 11 ]. No clear difference in normalised particle size distributions have been observed between ES and NS particles emitted during cutting or polishing [ 11 , 27 ].
Both quartz and cristobalite make up the total RCS content of ES emissions. Quartz tends to be the predominant silica form of ES emissions, but certain samples contain more cristobalite than quartz [ 6 , 8 , 11 , 23 , 27 , 28 ]. Negligible levels of tridymite have been observed in ES emissions [ 11 ]. This confirms that air (dust) monitoring for RCS workplace exposure assessments should include all forms of crystalline silica. In comparison, NS such as granite only generate quartz when fractured [ 27 ].
Comparing RD and RCS levels generated through processing several types of stones (resin-based and sintered ES, and NS), Hall et al. () [ 11 ] showed that the levels of airborne dust in different size fractions (inhalable, thoracic and respirable fractions) are comparable among the stones, but the levels of RCS were reflective of their bulk crystalline silica composition. This means that processing traditional high-Si ES (>90%) generated high levels of RCS (up to 80% by weight of RD), and accordingly, processing reduced-Si ES products generated lower levels of RCS [ 8 ]. This also applied to NS, for example, with processing sandstone (62% silica by weight) generating up to 55% by weight RCS [ 11 ], although other studies [ 27 , 28 ] observed that granite (NS) generated more respirable dust per unit volume of material compared to ES.
The emissions generated through processing ES have been well characterised in terms of the size, mass, and physico-chemical characteristics of associated respirable dust (RD) and respirable crystalline silica (RCS), as well as other airborne hazards. These emissions are often a function of the fabrication task, tools used and control measures applied during the task.
This is an important future research direction as emerging ES benchtop products containing inorganic waste, recycled glass and amorphous forms of silica, rather than crystalline silica, may still pose a risk to worker health. More research is needed to understand the composition of dusts generated by processing new-generation reduced and zero-silica resin-based, and sintered ES products.
Evidence also suggests that processing resin-based ES at high temperatures can lead to more variable hazard emissions and potentially more diverse health effects compared to sintered ES, which have already been subjected to high temperatures during manufacture. An example is the VOCs produced when processing resin-based ES [ 8 , 11 ]. In the case of sintered ES, which is harder than resin-based ES, there is uncertainty as to whether the additional mechanical energy and different abrasive action required in processing sintered stone results in different particle characteristics. Both Carrieri et al. () [ 28 ] and Thompson and Qi () [ 27 ] reported that reduced-Si sintered ES containing predominantly aluminosilicates (clays, feldspars) and recycled glass, respectively, and generated similarly fine particles (<1 µm in aerodynamic diameter) as &#;traditional&#; high-Si ES during cutting.
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Many of the new-generation reduced-Si ES contain recycled materials such as glass (amorphous silica) and ceramic wastes, bound together with polymeric resins. Some manufacturers of ES have also reported feldspars in their production. Feldspars are minerals containing aluminium and varying amounts of potassium, sodium, and calcium [ 35 , 36 ]. While there is limited evidence of comparable exposure outcomes for the different types of ES, it seems perhaps reasonable to expect their bulk constituency to be reflected, to some extent, in their emissions.
It is generally agreed that the bulk composition of ES is representative of the emissions generated. For example, processing high-Si ES generates high levels of RCS dust, which in turn is proportionately lower when reduced-Si ES products are processed [ 8 , 27 ]. There is also evidence of other ES bulk constituents being made airborne during active processing, including transition metals like Ti and Co [ 8 , 34 ] and VOCs as a result of resin decomposing when ES is cut [ 7 , 11 ].
3.3. Workplace Exposure Controls
The extent of health risks from crystalline silica are associated with airborne silica dust exposure, not simply the crystalline silica content of the bulk material. Silica dust exposure is in turn determined using several additional factors such as manufacturing processes and dust control measures in place that influence the overall RCS dust generation. For example, in the ES context, silica exposure intensities have been defined as the proportion of time using ES and dry processing (without water suppression) [5].
This section provides an outline of what is known about the relative efficacies of exposure controls according to conventional occupational hygiene practice. The Australian situation provides context.
Beyond what is now being mandated in Australia by the model occupational health and safety Regulations, a combination of control measures is often advised for controlling RCS exposures to below the current Australian 8 h Workplace Exposure Standard (WES) of 0.05 mg/m3 to prevent disease. To date, regulatory action in Australia typically entailed the prohibition of uncontrolled dry abrasive processing, the use of integrated tool vacuum systems, wet methods, and fit-tested personal respiratory protection.
Controlling exposures to hazards in the workplace is vital to protecting workers. The so-called hierarchy of control measures, as described in Regulation 36 of the Model Work Health and Safety (WHS) legislation, can be applied to this occupational health problem. The hierarchy of controls is a way of determining which actions will best control exposures through five levels of actions to reduce or remove hazards. The preferred order of action based on general effectiveness is: Elimination, Substitution, Engineering controls, Administrative controls and Personal protective equipment (PPE) [37]. Relevant available literature evaluating control measures in engineered stone and related industry settings is presented in Table 1.
The world-first ban on the use, supply and manufacture of ES in Australia represents the application of Elimination as the highest form of control in the hierarchy (removing the hazard at the source) to supplement existing controls. Evidence is already seen of industry pivoting in response to the ban. Next generation &#;low/reduced-&#; to &#;zero-silica/silica-free&#; products are becoming available on the market (see section The Unfinished Product&#;The constituents), and porcelain and ceramic products are exempt from the ban. In effect, this represents Substitution in the hierarchy of controls, as benchtop products will still be available. Effective substitution involves using a safer alternative to the source of the hazard. However, when considering a substitute, it is important to compare the potential new risks of the substitute to the original. New research into the emissions from these emerging products is needed to understand the relative risks compared with their high-silica ES predecessors as well as &#;traditional&#; natural stone products such as granite and marble.
Engineering control measures reduce or prevent hazards from coming into contact with workers and can include modifying equipment or the workspace, using protective barriers, ventilation, enclosing/isolating processes and more. Examples commonly used in the ES industry have included the on-tool water suppression of dust (wet processing) and/or dust extraction devices such as on-tool dust extraction or local exhaust ventilation (LEV). Water jet cutting via the use of CNC machines is applicable for the factory setting, but not for on-site installation. In fact, automation (e.g., CNC machines) have been shown to result in lower exposures than hand tools due to the operator position being further from the cutting edge. Local Exhaust Ventilation (LEV), particularly on-tool LEV, has previously been shown to be effective in respirable dust control in concrete grinding and polishing [38,39,40].
A combination of wet process methods and LEV can suppress dust more effectively, by a factor of 10 or more, compared to if a single control measure was applied [41,42]. For example, Cooper et al. () [41] reported short-term (30 min) RCS levels of 44 mg/m3 for dry activities, which reduced to 4.9 mg/m3 through the adoption of wet methods and further reduced to 0.6 mg/m3 when the latter measure was combined with LEV. This is because workers using predominantly wet methods may still carry out brief dry operations, for example, during finishing processes such as smoothing the edges or holes. Dry work is not uncommon during in-home installation of benchtops, where water suppression methods may not be available, and finishing tasks end up being carried out manually (i.e., dry finishing). Glass et al. () [5] observed that, even though there has been a 5-fold reduction in the proportion of time that ES workers spend on dry operations from their earliest job to the most recent, 16% of them still reported dry-processing at least 50% of the time. Recently, Weller et al. () [23] also found that despite all studied worksites using wet methods for ES processing, a substantial number of workers were likely exposed to RCS above the WES if not wearing respiratory protection. Wet dust suppression methods in combination with on-tool LEV may therefore be required to prevent overexposure to RCS while working with ES [26,43,44].
Qi and Echt () [45] reported significant improvement with the addition of sheet-wetting engineering control when hand grinding ES. They noted that neither the centre feed nor the water spray method provided an effective wetting of the active grinding spot on the stone countertop. This resulted in partially dry grinding during the operation. Similarly, our previous work [46] simulating tasks with pneumatic grinders and polishers also found that water jets on the grinder were not consistently and uniformly contacting the cutting surface, and this resulted in variable dust suppression outcomes. Salamon et al. () [24], in a study of four facilities in Italy, found LEV to be effective in wet and dry finishing and stated there was a remarkable reduction in RCS exposures.
Administrative controls establish work practices that reduce the duration, frequency, or intensity of exposure to hazards, and should only be used to provide additional protection after implementing substitution and engineering controls. Administrative controls rely on worker behaviour and include work practice policies, training, and good housekeeping, among others. There has been limited evaluation of interventions to improve the knowledge and practice for silicosis prevention amongst high-risk workers [47,48]. The knowledge, attitudes and behaviour of workers in workplaces is further discussed in section The Host. Education and training interventions must consider workers&#; demographic factors that can influence their effectiveness, with high proportions of culturally and linguistically diverse and vulnerable migrant workers represented in this industry in Australia [49] and likely elsewhere.
Like administrative controls, PPE requires consistent and ongoing effort by workers and their supervisors to effectively control exposure. Limited data are available on PPE (specifically respiratory protection) performance in relation to ES dust exposure control. Respiratory protective equipment can be an unreliable control measure and failure to conduct respirator fit testing on workers has been a frequent problem in this industry [23,50]. Recently, Weller et al. () [23] reported that Class P2 or N95 respirators providing an assigned protection factor (APF) of 10 (in accordance with Standards Australia/Standards New Zealand AS/NZS -) provided adequate protection for workers who were clean shaven and fit tested, when used in combination with wet dust suppression methods. The impact of facial hair on respirator protection performance has also been highlighted as an issue in compliance programs [51]. Weller et al. () [23] suggested that powered air-purifying respirators (PAPR-P3) provide a higher APF of 50 and may overcome the issue of workers with facial hair while also being more comfortable, especially in summer. One challenge of respiratory protection use is that workers doing hand polishing or grinding wearing PAPRs can have their visibility obscured by water splashing onto the visor, which may impact use compliance.
Overall, there currently does not appear to be consensus on &#;best practice&#; for effective wet methods for dust control or LEV to allow for the capture of dust at the source. Regardless of the silica content of the bulk ES product being processed, it will continue to be vital to adopt multiple control measures, used in combination (e.g., wet-cutting and appropriate fit-tested respiratory protection) when processing ES to reduce exposure.
Table 1.
Literature examining the use of engineering controls such as wet suppression and local exhaust ventilation in industries related to engineered stone. Presented in chronological order, RCS values represent Geometric Mean.
Reference Industry, Material/s and Tasks Control Measures Studied Major Outcomes Croteau et al., . [38] Construction.Dry tuck-point grinding, concrete surface grinding, angle grinder, paver block and brick cutting (masonry saw), concrete block cutting (hand-held saw).
Continuous 15 min each task (controlled simulation). Personal and area sampling. LEV: (on-tool shrouds) ventilation rates 0, 30, 75 cfm LEV reduced personal exposure levels to RD (and RCS) by 85&#;99%:
22.17 mg/m3 to 3.01 mg/m3 RD, and 3.04 to 0.47 mg/m3 RCS during tuck-point grinding;
165.34 to 8.00 mg/m3 RD, and 29.16 to 1.70 mg/m3 RCS during surface grinding;
89.95 to 4.31 mg/m3 RD, and 22.25 to 0.95 mg/m3 RCS during paver cutting;
26.69 to 3.67 mg/m3 RD, and 4.24 to 0.60 mg/m3 RCS during brick cutting.
Reduced clean up. Healy et al., . [40] Stonemasonry/restoration.
Grinding sandstone; 5-inch angle grinder.
Tool (cup grinder) ~ RPM
15 min each task (controlled simulation) (10 min no shroud). Personal sampling. LEV: 4 x on-tool shrouds
(FLEX, Dust Muzzle, Dustie, Hilti) LEV reduced RD personal exposure when grinding by 92% (7.1 to 0.5 mg/m3) and RCS by 99% (4.2 to 0.03 mg/m3) (all data). Cooper et al., . [41] Engineered stone (85% quartz), slab 1.4 m × 0.8 m × 19 mm.
Handheld worm-drive circular saw.
Simulated in 24 m3 tent (3.1 m × 3.1 × 2.1 (2.7 vaulted roof)).
Performed 4 × 30 min trials, 6 mm deep 3 mm wide cuts (27 cuts total). Order of trials randomised within each replicate block. Total of 3&#;5 trials per day with periodic rinsing of the area. Personal sampling. One field blank per day. Wet blade; wet blade + water curtain spray; wet blade + LEV
Mean quartz content of respirable dust was 58%.
RD and RCS:
Dry cutting 69.60 mg/m3 (RD) and 44.37 mg/m3 (RCS).
Statistical difference (by a factor of 10) between RD exposure using wet blade only (4.934 mg/m3) and wet blade + LEV (0.225 mg/m3),
but not between wet blade only (4.934 mg/m3) and wet blade + curtain 3.813 mg/m3).
Similarly for RCS, 4.934 mg/m3 for wet blade only, 3.813 mg/m3 wet blade + curtain and 0.604 mg/m3 wet blade + LEV.
Cutting, grinding, polishing, drilling.
Grinder ~10,000 RPM
Polisher ~ RPM
Trial 20 min (controlled experiments).
Personal sampling. Wet (sheet-flow); On-tool LEV; Wet + LEV Sheet-flow wetting + on-tool LEV during cup wheel grinding effectively reduced RCS by 50%; 1.128 mg/m3 with LEV, 2.115 mg/m3 without LEV.
Water-spray-wetting on grinding cup LESS effective when combined with LEV! That is, 2.988 mg/m3 with LEV, 0.434 mg/m3 without LEV. Enis, C.B., . [52] Engineered stone (Caesarstone; <93% quartz and <50% cristobalite), 2 cm thick slab.
Simulated/controlled grinding using hand-held 10cm (electric) grinder with diamond cup wheel (~ RPM).
20 min controlled trials (n = 3&#;4); 45-degree edge grinding. Personal sampling. Total of 5 field blanks each day. Combination of controls:
Low flow LEV (one vac), High flow LEV (two vac),
Sheet flow wet no LEV,
Sheet flow wet with low flow LEV, and
Sheet flow wet with high flow LEV. RD:
Dry grinding, High flow LEV (6.11 mg/m3) more effective than Low flow LEV (13.85 mg/m3)
Sheet flow wet grinding; with High flow LEV (0.90 mg/m3) and Low flow (1.39 mg/m3) more effective than Sheet flow wet no LEV (3.83 mg/m3).
Sheet flow wet High flow LEV not significanly different to Sheet flow wet Low flow LEV.
Wet polishing (in a workplace) using sheet-flow wetting.
Sample length 40&#;150 min only.
Personal sampling. Ventilation:
Retractable paint booth (on/off) 19&#;81% (mean 57%) of respirable dust was RCS.
No significant difference between on/off operation, but qualitatively lower when booth operating (RCS 73.62 µg/m3 booth off, 34.72 µg/m3 booth on). Saidi et al., [54] &#;Granite&#; polishing (dry).
Simulated test bench and LEV.
NaCl particles used to &#;simulate granite particle&#;.
Area/static sampling. LEV: push-pull system, dust shroud, tool integrated with suction slots No specific particle concentrations provided, results presented only as %efficiency.
All LEV systems effective, up to 95% reduction in NaCl.
Confirmed that suction flowrate and speed of rotating discs influenced LEV performance. Qi and Echt . [45] Workplace exposure assessment at three facilities processing (including grinding task) engineered stone. Personal sampling and some area sampling. Workplace wetting methods:
Water spray from a nozzle on a grinder,
Centre-feed built into grinder,
Combination of water spray and sheet-wetting methods Both water spray (190.4 µg/m3) and centre-feed (168.4 µg/m3) methods performed equally poorly at wetting the grinding spot and reducing worker&#;s RCS exposure during grinding, despite having very different water flowrates.
Adding sheet-wetting significantly reduced RCS exposure (33.2 µg/m3). Salamon et al., [24] Workplace exposure assessment at facilities processing artificial/engineered stone.
51 personal RCS samples. Workplace had existing engineering controls:
Extraction wall booths;
Aspirated benches.
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General outcomes:
Extraction booths good for minimising general ambient dust load but not necessarily reduced personal exposure.
RD and RCS:
Wet manual processing reduced RD exposure (0.352 mg/m3 dry, 0.082 mg/m3 wet) and RCS exposure (0.039 mg/m3 dry, 0.020 mg/m3 wet).
Aspirated benches achieved high capture speed near finishing operations and significantly reduced RCS levels. Weller et al., [23] Workplace exposure assessment at facilities processing artificial/engineered stone.
123 personal RCS samples (34 static) across 27 workshops in Sydney. All used wet methods of fabrication.
GM of pooled result for RD was 0.09 mg/m3 and 0.034 mg/m3 for RCS.
The highest exposed workers with a GM RCS of 0.062 mg/m3 were those using pneumatic hand tools for cutting or grinding combined with polishing tasks.
Workers operating semiautomated routers and edge polishers had the lowest GM RCS exposures of 0.022 mg/m3 and 0.018 mg/m3, respectively.
The wearing of respiratory protection by workers remains necessary until further control measures are more widely adopted across the entire industry, e.g., reduction in the crystalline silica content of ES. Open in a new tab
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