OSHA Online Center reports that approximately two million workers in the construction industry are exposed to respirable crystalline silica. Another 300,000 workers in the production of bricks, hydraulic fracturing, and foundries endure exposure to silica dust. It might be 100 times smaller than sand particles found on playgrounds and beaches, but silica dust has serious health effects on individuals exposed to it. Inhaling, the fine particles of silica, which are found in stone, concrete, bricks, and sand, causes scarring and inflammation in the lungs. Continuous exposure leads to silicosis, lung cancer, renal disease, and chronic obstructive pulmonary disease. Mitigating this invisible hazard is crucial to minimize the health and safety risks of industrial workers. And one of the best techniques is implementing engineering controls, which alters the characteristics of tasks like drilling, grinding, and cutting stone to reduce the generation and dispersion of construction dust at worksites.
Wet Dust Suppression
Dry cutting, grinding, and drilling of stone, concrete, and brick causes microscopic silica particles to form and become airborne. Using wet production methods helps suppress dust, as water droplets absorb or bind the small particles of silica. Once absorbed by water, the dust becomes heavy, falls down to the ground, and stays on the surface, so the workplace remains dust-free. The techniques used in wet dust control include misting and fogging, on-tool wet methods, foam-based systems, and applying chemical additives. The on-tool wet method, for instance, involves spraying water continuously at the point of contact, like a blade, grinding wheel, or bit, to capture dust the moment it’s formed, preventing it from floating in the air.
For misting and fogging, constructors and manufacturers use different nozzles and spray patterns to control dust, depending on the work environment and type of particles formed. For example, in environments where fine silica is generated, smaller misting nozzles are used to create a cloud of tiny water droplets that bind microscopic dust. To control heavier or larger particles, larger sprays are more suitable. Adding foam and chemicals to the water supply used in wet cutting minimizes surface tension, ensuring moisture binds with dust efficiently. Caution must be taken, however, to prevent respirable dust from regenerating into the air. This includes managing slurry using an M or H class vacuum before it dries up while adequate water is needed to prevent sludge, which doesn’t mitigate airborne dust.
Local Exhaust Ventilation
Airborne contaminants like silica grains must be captured and eliminated directly at the source before it contaminates the breathing zone. And an effective approach in manufacturing and construction is using a local exhaust ventilation (LEV) system. A LEV works the same way as a household vacuum cleaner. It uses a shroud or enclosure around the cutting and grinding equipment or tools and collects silica particulates or dust in the hood at the point of dust emission. The duct system then sucks in the toxic air and transports it inside the local exhaust ventilation unit while HEPA filters attached to the system clean the contained air by trapping the tiniest silica granules before it’s released. There’s also a fan, known as the ‘power source of extraction’ that pushes air from the duct and into the exhaust stack. Air is then pushed out from the LEV and into a safe space through the exhaust valve.
A slight mistake during the installation of the LEV and workers positioning can create a false sense of safety against silica dust exposure. It’s therefore crucial that workers learn how to identify and handle silica carefully to prevent health hazards. Enrolling in a silica awareness course can be helpful as it teaches builders and manufacturers how to recognize silica-containing materials and other toxins like asbestos, and how to control them on site. Employees also learn early symptoms of exposure (chronic fatigue and shortness of breath), how to set up engineering tools, and industry regulations for safe dust control measures.
Automation and Robotics
Robotics has revolutionized safety rules in construction, as they take on high-risk tasks and eliminate the need for human intervention, thus reducing exposure to harmful respirable particles. For example, autonomous drilling and cutting allows operators to operate robotic drilling rigs or blades remotely, meaning humans aren’t exposed to harmful materials. Plus, automated machines still employ dust control measures like wet suppression to trap particles at the direct source of emission. Clean-up automation also prevents manual sweeping, which exposes humans to inhale dust as it floats in the surroundings. Using AMRs or autonomous mobile robots equipped with HEPA filtration and water flooding systems helps clean settled silica without re-suspending them into the atmosphere. Automating enforces safety measures consistently, minimizing stop-work or downtime incidents caused by excessive debris and dust generation at worksites.
Combining engineering controls in the prevention of construction dust is critical for protecting employees from serious respiratory health risks. Employers can implement the on-tool wet suppression method, misting, applying chemical additives, and using local exhaust ventilation to stop fine particles and debris from spreading. Robotics play a critical role in removing workers from the vicinity of areas likely to be contaminated by silica and reinforcing safety parameters.
