13th October 2026
Respirable crystalline silica is one of the most seriously regulated workplace airborne hazards in the UK. For businesses handling silica-bearing materials in enclosed processing and manufacturing environments, controlling silica dust is not optional. It is a legal requirement under COSHH, and the Health and Safety Executive has made clear in recent years that it expects employers to demonstrate active, effective control measures rather than simply monitoring exposure levels and hoping for the best.
Dry fog dust suppression offers a practical, cost-effective solution for indoor silica dust control that integrates neatly into existing processing operations without disrupting workflow or requiring significant infrastructure changes.
Silica is found in a wide range of naturally occurring materials including sand, sandstone, quartz, granite, slate, and clay. When these materials are cut, crushed, ground, drilled, or processed, fine particles are released into the air. Particles in the respirable range, broadly those below 10 microns, are small enough to penetrate deep into the lungs where they cannot be cleared naturally.
Prolonged exposure to respirable crystalline silica (RCS) causes silicosis, an irreversible and potentially fatal lung disease. It is also a recognised cause of lung cancer and is associated with other serious respiratory conditions. The Workplace Exposure Limit (WEL) for RCS in the UK is 0.1 mg/m³ as an eight-hour time-weighted average, one of the lower exposure limits for any industrial substance, reflecting how seriously the hazard is treated.
The industries and processes where RCS exposure is most significant in enclosed environments include:
Stone fabrication and monumental masonry, where cutting, grinding, and polishing of natural and engineered stone generates very high concentrations of fine silica dust. Ceramics and pottery manufacturing, where dry clay, silica flour, and other silica-bearing materials are handled, mixed, and processed. Quarry processing buildings, where stone is crushed, screened, and graded in enclosed or semi-enclosed plant. Construction material manufacturing, including brick, tile, concrete block, and aggregate production. Foundries, where silica sand is used extensively in moulding and casting processes. Glass manufacturing, where silica sand is a primary raw material handled in large volumes.
In all of these environments, dust generation is a routine part of normal operations rather than an occasional event, which means control measures need to be continuous and reliable rather than reactive.
The effectiveness of any dust suppression system depends on its ability to agglomerate with dust particles at the point of generation before they become airborne and disperse. This requires droplets that are close in size to the dust particles being controlled.
The Sonicom ultrasonic nozzle generates droplets of 10 microns or less by passing compressed air at around 5 bar through the nozzle body, creating an ultrasonic shockwave that shatters the water into an ultra-fine mist. At this droplet size, the system is targeting the same size range as the respirable dust particles themselves, maximising agglomeration and causing particles to combine and settle back onto the material body rather than remaining airborne.
Critically, because the droplets are so fine, the system adds moisture to the air and the dust without wetting the material, surrounding surfaces, or equipment. This makes it suitable for environments where surface wetting would cause operational or product quality problems.
Dry fog suppression systems are designed to be installed at the specific points where dust is generated rather than attempting to treat the whole building atmosphere. Typical installation points include crusher and mill discharge points, screening and grading equipment, conveyor transfer points, hopper and bin filling operations, and loading and unloading areas within the facility.
Nozzle placement is targeted to create a fog curtain or cloud at the point of dust release, intercepting particles before they disperse. The system runs on compressed air and a standard water supply, both of which are generally available as existing site utilities in processing and manufacturing facilities. Controls can be linked to process equipment so suppression runs only when the relevant machinery is operating, minimising water consumption and keeping the environment as dry as possible between production runs.
COSHH requires employers to prevent or adequately control exposure to hazardous substances. For RCS, the HSE expects a hierarchy of controls to be considered, with dust suppression at source sitting above general ventilation and respiratory protective equipment in that hierarchy. A well-designed dry fog suppression system, installed at the points of dust generation and maintained correctly, can form a central part of a defensible COSHH compliance strategy.
It is worth noting that suppression should be considered alongside, rather than as a complete replacement for, other controls such as local exhaust ventilation where appropriate. The combination of source suppression and good ventilation typically delivers the most robust overall control.
For many businesses in stone fabrication, ceramics, quarry processing, and related industries, the choice is not between dust suppression and doing nothing. It is between different approaches to meeting a regulatory obligation they already have. Dry fog suppression consistently compares favourably against alternatives such as bag filter ventilation systems on both installation cost and running cost, while delivering targeted control at the source rather than attempting to capture dust once it has already become airborne.
If you handle silica-bearing materials in an enclosed environment and would like to discuss how a Sonicom dry fog system could form part of your dust control strategy, the J D UltraSonics team is happy to help.