Managing Airborne Dust: Health, Legal, and Safety Implications
Unlike material spillage, which generally stays close to the point on the conveyor where the material is released, airborne dust affects the entire operation. Once dust is released into the air, it will settle wherever the air currents take it. There are many dangers, expenses, inconveniences, and inefficiencies associated with airborne dust.
It is in an operation’s legal and financial best interest to properly manage dust.
When an operation violates a safety regulation, there are legal ramifications for the responsible parties, including personal culpability and possible financial liability for executives of operations where safety violations occur. Therefore, there is a personal incentive to eliminate dust.
Health Risks
The greatest danger of dust is the exposure of workers, neighboring homes, and businesses to it. If the material is toxic, carcinogenic, or otherwise hazardous, having it airborne can endanger many people. In addition to the toxic dangers of materials, there is a respiratory danger presented by airborne dust. Once respirable dust is inhaled into the lungs, it might not be expelled. Prolonged exposure will lead to a buildup of material in the lungs. Most regulatory agencies define 10 microns as the size of respirable dust. When airborne particles 10 microns or smaller are inhaled, they will stay in the lungs; therefore, dust particles of 10 microns or smaller have a much lower allowable concentration. With toxic materials, the allowable concentration is even lower. In the United States, silica is normally regulated to the point where maximum allowable concentrations are below 2 milligrams per cubic meter (2.0 x 10.6 oz/ ft³) per eight-hour day. Many government and private agencies have deemed that continued exposure to concentrations higher than these will cause silicosis.
OSHA has determined permissible dust levels for the United States. The levels determined by OSHA are representative of regulations seen and increasingly enforced around the world.
Explosion Risks
Another danger of dust is its potential for explosion. Materials that have this potential include coal and other fuels. Even materials that are not flammable in their bulk state can combust when airborne as fine dust. For example, aluminum dust is flammable.
There are five necessary components for a dust explosion to occur. The first three form the "triangle" of components of any fire:
- Fuel (ignitable dust)
- Ignition source (heat or electric spark)
- Oxidizer (oxygen in the air)
- Suspension of the dust into a cloud (in sufficient quantity and concentration)
- Confinement of the dust cloud
If any one of these components is missing, there can be no explosion. Many businesses offer products and solutions to counter the requirements for an explosion, but controlling ignitable dust will decrease the chance of an explosion and increase the effectiveness of these products.
It is the responsibility of plant owners and management to be aware of the explosive properties of materials in their various states and to actively eliminate the potential for explosions.