The quarrying and aggregates sector page explains where silica exposure arises; this page covers the controls themselves. Dust suppression in a quarry is an engineered system, not a collection of hoses — and each element, from drill sprays to cabin filtration, only counts as a control if its performance can be verified.
Quarry dust control should be designed as an integrated engineering system. A spray nozzle, enclosure or cabin filter cannot be assumed to provide control merely because it has been installed. Its performance depends on correct selection, positioning, operation, maintenance and verification under normal and adverse operating conditions.
Control design should consider changes in material moisture, feed rate, product size, equipment configuration, wind and ambient temperature. Controls should start before material processing begins and remain operational during shutdown where residual material movement can continue to release dust. Interlocks can prevent plant from operating when essential sprays, extraction or filtration systems have failed.
Verification should be planned at the design stage. Each control should have an observable or measurable performance indicator, such as water flow, spray pressure, material moisture, extraction airflow, enclosure pressure, filter condition or particulate concentration. A control without a means of verification can remain ineffective for long periods without being recognised.
Water suppression works best when moisture is applied at the point where dust is created or immediately before the material reaches that point. Spraying a general area from a distance may dampen settled dust but often has limited effect on a concentrated plume released inside a crusher, screen or transfer chute.
At drills, the water supply must reach the cutting zone and operate at a rate compatible with the drill, geology and spoil-removal system. Blocked passages, leaking couplings and inadequate supply pressure can reduce performance even while water remains visibly present around the machine.
At crushers and screens, nozzles should be positioned to intercept the material and airborne dust without being destroyed by impact or buried by product. Spray patterns should overlap where necessary, and the droplet size should be suited to the dust cloud. Very coarse droplets may pass through fine dust, while excessively fine mist may be carried away by wind or evaporate rapidly.
At transfer points, pre-wetting the material before it falls is often more effective than attempting to suppress a fully developed plume. Controls should avoid excessive water that causes screen blinding, product-quality problems, slippery access routes or contaminated run-off.
Verification should include nozzle inspections, flow and pressure checks, observation under full load and comparison of dust conditions with the system operating correctly and under suspected degraded performance.
Haul-road dust control depends on road construction and traffic management as much as water application. A poorly graded surface with loose fines will dry rapidly and generate dust under heavy vehicle movement even when a water bowser operates frequently.
Roads should be maintained to prevent the accumulation of fine loose material. Grading, repair of potholes, drainage and removal of spillages reduce the amount of dust available for re-suspension. Watering schedules should respond to traffic intensity, weather, road condition and drying rate rather than operating at a fixed frequency regardless of conditions.
Approved chemical suppressants may provide longer-lasting treatment in suitable areas, but they require assessment of soil, water, product and equipment effects. Their use should be consistent with local environmental approvals and manufacturer requirements.
Speed control reduces both dust generation and collision risk. Limits should be supported by signs, supervision, road design and vehicle-tracking data where available. Wheel-wash systems can reduce the transfer of mud and fines onto paved roads, but they require adequate drainage, sediment removal and inspection of the exit route.
Road performance can be verified through inspection during representative traffic, visible-plume observations, surface-moisture checks and particulate monitoring at selected downwind points.
Conveyor controls should prevent wind from stripping fine material from the belt and contain dust released where material is loaded, discharged or changes direction. Covers are most effective when they are continuous, securely fitted and compatible with inspection and maintenance.
Transfer chutes should guide material rather than allowing uncontrolled free fall. Reducing drop height lowers impact energy and the displacement of dust-laden air. Adjustable or telescopic loading arrangements can maintain a short distance between the discharge and the receiving stockpile, truck or vessel as the receiving level changes.
Skirting should contain material at loading points without rubbing excessively against the belt. Impact beds and correctly aligned chutes reduce spillage, while sealed inspection doors prevent uncontrolled openings in an otherwise enclosed system.
Covers alone may not control the air displaced from a high-capacity transfer. Where pressure builds inside the enclosure, a designed extraction or filtration system may be needed. Verification should include inspections for damaged covers, gaps, spillages, worn skirts and visible leakage during full production.
Enclosure isolates the dusty process from the surrounding workplace. It should be as complete as operational access allows, with openings kept small and positioned away from the direction in which dust-laden air naturally moves.
Local extraction should maintain inward airflow through necessary openings. The extraction volume must account for air displaced by falling material and moving equipment. Poorly positioned hoods may draw clean air around the plume while allowing contaminated air to escape.
Ductwork should be designed for the transported dust, with suitable velocity, abrasion resistance and access for cleaning. Collectors and filters require differential-pressure monitoring, safe disposal of collected material and maintenance arrangements that do not create a secondary exposure problem.
Enclosures should be checked under representative load using smoke, airflow measurements or another suitable visualisation method. Escaping dust, open access doors and deposits around joints indicate loss of containment. Extraction performance should be measured rather than judged only by fan noise.
An enclosed vehicle cabin is protective only when contaminated outside air is prevented from entering. Recognised NIOSH practice includes a filtered fresh-air supply, positive pressurisation, effective door and window seals and a recirculation filtration system. Doors and windows must remain closed for the system to work as intended.
Cab maintenance should include filter replacement according to condition and pressure loss, inspection of seals, cleaning using methods that do not re-aerosolise dust and measurement of cabin pressure. In-cab particulate testing can provide direct evidence of performance. A visibly clean cabin does not by itself demonstrate effective respiratory protection.
Stockpiles should be positioned, shaped and managed to minimise wind erosion. Measures may include limiting unnecessary height, maintaining suitable surface moisture, applying approved surface stabilisers, orientating piles with regard to prevailing winds and avoiding uncontrolled discharge from excessive height.
Wind fencing should reduce wind speed across the stockpile rather than create severe turbulence. Its location, height and permeability should be designed for the pile geometry. Performance should be checked during the wind conditions for which the fence was intended.
The quarry control programme should combine engineering inspections with dust measurements and operating records. A low result on one day does not prove that controls will remain effective during a different material feed, wind condition or production rate.
Controls should be selected, positioned, operated, maintained and verified together, with interlocks preventing plant from running when essential sprays or extraction have failed.
Moisture applied where dust is created — at drills, crushers, screens and transfer points — outperforms distant area spraying, with droplet size matched to the dust cloud.
Enclosure isolates the process and extraction maintains inward airflow; both need checking under representative load rather than judging by fan noise.
Every major control needs an observable indicator — flow, pressure, airflow, filter condition or particulate concentration — plus defined acceptance criteria.
No UAE provision has been found that prescribes specific quarry dust-control measures or requires silica air monitoring. The only published exposure limit this site cites is Abu Dhabi's Occupational Standards and Guideline Values document (2016), Schedule A: crystalline silica as alpha-quartz and cristobalite, 8-hour TWA of 0.025 mg/m³ respirable, classified A2. That document is not a Code of Practice, describes its own values as non-mandatory, and is now recorded as suspended by the Abu Dhabi Public Health Centre under the renamed ADOSH-SF framework, which directs entities to relevant local or federal standards in force. It is a published reference point, not an enforceable UAE limit. Control practice described here reflects recognised international guidance, which UAE operators commonly adopt as good practice.
No. The water must reach the dust-generation zone with an appropriate flow, pressure and spray pattern. Visible wetting away from the source may provide little control.
No. Effective control depends on filtered air, positive pressure, intact seals, closed doors and windows, clean interiors and maintained filters.
Not always. Covers reduce wind effects and contain material, but extraction may still be needed where displaced air pressurises the enclosure or where openings cannot be adequately sealed.
Evidence should combine inspection, operating parameters, maintenance records and representative dust measurements. Each major control should have defined acceptance criteria and a corrective-action process.