 grit media. However, blasting operations may increase airborne concentration of Beryllium dust to above the permissible exposure limit (0.2 mg/m3). For example, coal slag containing a mere 4 ppm (0.0004 weight percent) used during dry blasting has been measured to result in airborne dust concentrations up to 9.5 μg/m3 (that's well above the 2.0 μg/m3 STEL).
This example and KTA-Tator's CDC reports illustrate how the new Final Rule for Beryllium may pertain to grit media containing less than the 0.1 percent beryllium by weight. Employers using materials with lower beryllium content are exempt only where the employer has objective data demonstrating that employee exposure to airborne beryllium will remain below the action level under any foreseeable conditions. Employers can use objective data, based on industry-wide surveys or calculations based on beryllium content and total concentration of airborne dust generated to represent typical exposures during operations to determine how their operations fit under the standard.
Backing an Exemption Claim
OSHA recommends testing all abrasives when they come in the door, as each batch may contain different amounts of Beryllium (even if It is not listed on the SDS). It’s also important to remember that substrates can also generate Beryllium dust, and add to airborne concentration, so monitoring is important to demonstrate to OSHA that controls work. If controls, equipment, etc. change, monitoring must be performed and reports generated (by third party labs) to back your claim of exposure below the action level.
Monitoring is generally already done for lead and other substances. The same micrometer and lead cartridge can be worn, in the same manner, and set to a low flow pump at 1-4 liters/min for the entire workday to get an appropriate reading, then sent off to the lab for analysis and reporting.
Minimizing Beryllium Exposure
One common-sense way to reduce beryllium in airborne dust is switch from dry abrasive blasting to wet abrasive blasting to reduce the total amount grit handled and consumed during blast operations, and to reduce the total amount of airborne dust generate. CleanerBlast offers equipment for wet abrasive vapor blasting (vapor blast) that uses 90% less grit and generates 91.7% less dust than dry abrasive blasting.
Depending on the particle size of the grit, CleanerBlast units also cut manual loading tasks in half or more, providing additional control. CleanerBlast equipment provides a true vapor blasting method to contain dust particles in several ways:
Minimal waste means a blastbag can be used when cleaning pipes to directly capture spent grit.
Spent grit from other operations or particles not immediately captured by using a blastbag are encapsulated in water droplets during vapor blasting. Vapor blasting equipment uses low pressure so it does not propel or disperse contaminated particulates Water weighs down the droplets and falls to the workspace floor where it can be vacuumed with a shop vac to prevent exposure.
Vapor blasting equipment is low pressure, so it does not widely disperse particulates widely or propel them at high speed to potentially penetrate worker skin.
A rinse hose can be simultaneously connected to CleanerBlast machines to safely remove any residual grit that may stick to damp surfaces.