EPA Self-Audit and Inspection Guide
Organic Finishing of Metals

Table of Contents

Carbon Dioxide Blasting: Regulatory Requirements

Air
The Clean Air Act regulates particulate matter in exhaust air (40 CFR Part 50). Large carbon dioxide blasting operations can create a sufficient amount of particulate matter consisting of coatings residue to subject facilities to Title V permitting requirements.

Solid and Hazardous Waste
Under the Resource Conservation and Recovery Act (RCRA), organic finishing facilities are required to manage listed and characteristic hazardous wastes (40 CFR Part 261). Waste from carbon dioxide blasting operations may be classified as hazardous depending on the type of coating material removed. Hazardous waste management (40 CFR Part 262) includes obtaining permits for the facility in order to generate wastes, meeting accumulation limits for waste storage areas, and manifesting waste containers for off-site disposal.

Each state and/or region is primarily responsible for the regulation of non-hazardous solid wastes (those not governed by the hazardous waste provisions of RCRA).

Health and Safety
Carbon dioxide blasting creates adverse conditions inside facilities which, while not regulated by EPA, should be addressed. Suspended coating particulates and excessive noise created by equipment can impact worker health and are regulated by the Occupational Safety and Health Administration. In addition, high levels of carbon dioxide gas, which is heavier than air, may accumulate in confined areas causing breathing problems for workers.

Self-Audit/Inspection

• Do dry residual coatings or carbon dioxide blast media come in contact with exhaust air streams? If so, do concentrations of particulate matter exceed limits established by facility air permits?

Do residual coatings come in contact with water streams? If so, do concentrations of pollutants exceed limits established by the facility NPDES permit or POTW discharge agreement? Are all residual coatings wastes labeled and packaged in accordance with 40 CFR Part 262, Subpart C? Are wastes contaminated with residual coatings classified as hazardous? If so, are the wastes handled and manifested in accordance with 40 CFR Part 262, Subpart B? Are hazardous wastes segregated from non-hazardous wastes?

Carbon Dioxide Blasting: Common Causes of Violation

• Carbon dioxide blasting creates a large volume of carbon dioxide gas. The gas is denser than air and may accumulate in enclosed spaces above acceptable limits for worker safety if proper ventilation is not provided.
Residual coating material forms dust in the blast area. Some particles may be small enough to qualify as respirable particulates capable of penetrating lung tissue. Typical hazards include exposure to silica and lead. Carbon dioxide blasting technologies generate a high level of noise. Equipment used to compress and pump the air and solid carbon dioxide, the exhaust of the carbon dioxide stream, and the media striking the substrate create sufficient decibel levels to require process engineering controls and hearing protection. Carbon dioxide blasting creates a waste of coatings residue. Based on the coating constituents, the waste may be classified as hazardous according to RCRA standards at 40 CFR Part 261.

Carbon Dioxide Blasting: Sources of Pollution Coating material and other contaminants are blasted off work pieces. This material can create a fine dust in the work area. Also, material that falls to the ground must be collected and disposed. Depending on the constituents of the coating material, the residue may be considered hazardous. Carbon dioxide gas may accumulate in the blasting areas. Noise is created from the equipment used to compress and pump the air and solid carbon dioxide, from the exhaust of the carbon dioxide stream, and from the media striking the substrate.

Carbon Dioxide Blasting: Pollution Prevention Alternatives

Carbon dioxide blasting may be considered a pollution prevention alternative since it aids in the proper application of coating materials thereby reducing rework or reject parts. Carbon dioxide blasting reduces or eliminates the hazards associated with chemicals, solvents, wastewater, and excess blast media created by organic solvent cleaning, chemical coatings removal, and mechanical coatings removal. Perform carbon dioxide blasting in enclosed areas such as blast booths or workcells that have adequate ventilation systems to contain noise and maintain safe levels of carbon dioxide. Optimize process to strip properly with minimal aggression. Proper adjustment of operating parameters, such as carbon dioxide pellet size and exhaust velocity, will improve coatings removal without damaging the substrate. Modify part arrangement to ensure that blast media reaches all surfaces. Minimize need for coatings removal by improving other process steps. Reduce coating failure by handling parts carefully, and by performing good cleaning, coating application and curing. Determine if time between rework can be lengthened to reduce need for mechanical coatings removal. Train employees on the safe operation of equipment and handling of wastes and encourage continuous improvement. Training familiarizes workers with their responsibilities, which reduces accidents and spills.