Employers can manage their hazardous emissions with careful planning and thoughtful engineering. With the proper controls in place, emissions of chemical vapor, dust or fine particles can be controlled to ensure workers’ safety. Engineering controls either minimize the generation of the contaminant or reduce the amount of contaminant in the air through various methods.
It is important that controls be designed to collect contaminants as close as possible to the source from which they are generated. This makes it easier to collect more contaminants. In addition, because the air is collected at the source, the facility could use a smaller collection system as compared to collecting air throughout the entire building. In some cases, engineering controls can be placed along the path a hazard travels to capture and remove the contaminant before it can impact workers’ health.
Ultimately, an engineering control system is designed based upon the specific contaminants in an environment.
Some contaminants are heavier than air, so the collection system must be installed to draw air from the lower portions of the workspace. For example, if a facility uses a woodworking system, it might need a collection point near where the sawdust is generated to recover dust and another system closer to the floor since the particles are heavier than air and, therefore, fall to the floor.
Other contaminants are lighter than air or, if emitted from applications where heat is involved, rise with the hot air. In that case, the facility may need a collection hood over the area where the emission is generated. For example, it may help to install a hood above a heated plating tank to collect evaporating chemicals at the source of generation.
If the hazard is generated throughout several points in the workspace, the space may require several general collection points. Using the woodworking example above, a facility with a process that pushes a wooden product through a fabrication line complete with saws, routers and grinders would generate dust across several points. As a result, there would be multiple collection points, potentially connected to the same dust collector.
For many facilities, the only engineering control necessary is adequate ventilation. However, other solutions might include process control and enclosure or isolation
Consider a plating shop, for example. A worker operates at a tank where a chemical is heated, causing the chemicals in the tank to evaporate into the air. One engineering control is putting plastic balls on the top of an open tank that contains solvents. This does not interfere with placement of metals in the tank for plating, but it reduces the amount of chemical evaporation.
The amount of the hazard generated at this source would be further reduced by installing a ventilation system to exhaust any remaining vapor outside.
Of course, if the amount of a substance the facility can emit to the outdoor air is limited by regulation, the emissions may need to be treated before they are exhausted. An emissions treatment system may include particulate filters to remove dust, activated carbon filters to absorb VOCs, or an afterburner to achieve complete combustion to control any contaminants before the treated air is released.
By studying potential contaminants of concern and understanding where the hazards lie, it is possible to design and install a highly efficient control system. But what if the facility team doesn’t know which contaminant is causing problems? Or if the installed control is working as intended? In the next chapter, we’ll discuss how to check for contaminants and confirm that all regulatory requirements are being met.
Click here to download our full Air Quality Guide: Controlling the Air Quality in Your Facility: What You Need to Know About Your Regulatory Requirements and Options for Compliance.