Metal Finishing Industry

Contact: Environmental Assistance Center, 800-662-9278
Agency: Environment, Great Lakes, and Energy

The Metal Finishing Industry is comprised of a large variety of operations. Some of the operations include electroplating (chromium, nickel etc.), electroless or non-electrolytic plating, chromic acid etching, other non-electrolytic metal coating processes, such as chromate conversion coating, electroforming, electropolishing, metal finishing, and dry mechanical polishing, electroforming, and electropolishing. While this list is not exhaustive of the industry, there will be a few specific types of processes highlighted in this guidance document. Furthermore, this guidance will reference additional resources that will help the regulated community and the general population to better understand the regulatory requirements that apply to this industry.

The United States Environmental Protection Agency (USEPA), has issued national regulations for the Metal Finishing Industry. These regulations are found in the National Emission Standards for Hazardous Air Pollutants (NESHAP) that are found in Title 40 of the Code of Federal Regulations, Part 63. Additionally, the Michigan Department of Environment Great Lakes and Energy (EGLE) Air Quality Division (AQD) regulates sources of outdoor air pollution, including emissions generated by the Metal Finishing Industry. This guidance will provide information related to the various types of metal finishing processes and the regulations that may apply. It will also include information on how to make permitting decisions.

Chromium Electroplaters

Chromium Electroplaters

In November 1994, the USEPA issued national regulations (NESHAP) to control air emissions of chromium from hard and decorative chromium electroplating and chromium anodizing tanks. The Clean Air Act Amendments of 1990 directs the USEPA to regulate emissions for a number of toxic chemicals, including chromium, from a wide range of industrial sources. Chromium electroplating and chromium anodizing tanks are one of the largest sources of chromium emissions in the United States. The hexavalent form of chromium is highly toxic and a known human carcinogen, causing lung cancer. Less is known about the cancer risk of the trivalent form of chromium, but it can accumulate in the lungs and may result in decreased lung function after continuous exposure. It is important to note that the NESHAP regulates the use of both trivalent and hexavalent chromium in electroplating processes.

Over 1,400 facilities perform chromium electroplating and/or chromium anodizing in the United States. Many facilities are small job shops that are located near residential areas. Hard chromium electroplating operations deposit a layer of chromium directly on a base metal to provide wear and corrosion resistance, low friction, and hardness (for hydraulic cylinders, industrial rolls, etc.). Decorative chromium electroplating operations deposit a thin layer of chromium on a base metal, plastic, or undercoating to provide a bright finish and provides wear and tarnish resistance (for bicycles, auto trim, tools, etc.). Chromium anodizing operations form a chromium oxide layer on aluminum to provide corrosion and wear resistance (for aircraft parts, architectural structures, etc.). Except for the trivalent chrome decorative process, which uses the trivalent form of chromium, all other chromium electroplating processes use the hexavalent form.

The Chromium Plating and Anodizing NESHAP is enforced by each district office of the Michigan Department of Environment, Great Lakes, and Energy, Air Quality Division.

The NESHAP was amended in 2012; and those amendments included changes to source compliance dates as well as emission limitations and the standards required for compliance. As of September 21, 2015, perfluorooctyl sulfonates (PFOS) based fume suppressants are prohibited from being added to tanks subject to the chromium electroplating NESHAP (Subpart N). Subpart N defines PFOS-based fume suppressants as a fume suppressant that contains one percent or greater PFOS by weight. There are a variety of PFOS-free alternatives available.

Technical Assistance Resources

Recordkeeping and Reporting Forms

  • NESHAP for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks: Use this set of twelve forms to comply with the recordkeeping and reporting requirements of National Emission Standard for Hazardous Air Pollutants (NESHAP) for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks.
  • Reporting Forms
    • Notification of Construction/Reconstruction: Word, PDF
    • Notification of Performance Test: Word, PDF
    • Performance Test Results: Word, PDF
    • Notification of Compliance Status: Word, PDF
    • Ongoing Compliance Status: Word, PDF
  • Recordkeeping Forms
    • Composite Mesh-Pad Systems or Combination Packed-Bed Scrubber/Composite Mesh-Pad Systems Operation and Maintenance: Word, PDF
    • Fiber-Bed Mist Eliminators Operation and Maintenance: Word, PDF
    • Packed-Bed Scrubbers Operation and Maintenance: Word, PDF
    • Monitoring Data: Word, PDF
    • Daily Process Operations: Word, PDF
    • Fume Suppressants

Nickel Electroplaters

Nickel electroplating provides a hard corrosion resistant finish and is often applied to other metals such as copper. It is almost always applied to other metals prior to decorative chromium electroplating as well. Airborne nickel is carcinogenic to humans and can also cause breathing difficulties in high concentrations. Nickel electroplating generates nickel in the respirable form. In 2019, the AQD re-evaluated the level of toxicity for nickel. Information on that evaluation can be found at the AQD's Air Toxics Screening Level Justifications website.

General Metal Finishing Industry

The scope of the general Metal Finishing Industry is broad and can include electroless or non-electrolytic plating, other non-electrolytic metal coating processes, such as chromate conversion coating, electroforming, electropolishing, metal finishing, dry mechanical polishing, electroforming, and electropolishing.

Permitting – Requirements and Exemptions

The AQD has established Permit to Install (PTI) exemptions and guidance for the Metal Finishing Industry. This section is designed to assist industry in determining compliance requirements for their operations. When trying to determine whether or not a PTI is needed, the AQD has developed the "Permit to Install - Determining Applicability Guidebook." This guidebook will help you decide what exactly is an emission unit and how that concept applies at your facility. It will also help you determine whether an exemption could apply to your emission unit. This guidebook is the first stop when conducting a process evaluation. After you have done the evaluation as described in the guidebook and reviewed the exclusions in Rule 278, the information below can help you to determine if a PTI is required, or if there is a PTI exemption that is right for your metal finishing operation. The rule identified in the flow chart below can be found in the Michigan Air Pollution Control Rules. The PTI exemptions can be found in their entirety in the Air Permit to Install Exemption Handbook.

R 285(2)(l)   R 285(2)(vi)   R 285(2)(r)
Do you own or operate the following equipment and any exhaust system or collector exclusively serving the equipment?
  • Die casting machines
  • Equipment for surface preparation of metals by use of aqueous solutions, except for acid solutions.
  Do you own or operate equipment for carving, cutting routing, turning drilling, machining, sawing, surface grinding, sanding, planing, buffing, sand blast cleaning, shot blasting, shot peening or polishing metals?

Is the equipment:
  • Used on a non-production basis?
  • That which has emissions that are released only into the general in-plant environment?
  • That which has externally vented emissions controlled by an appropriately designed and operated fabric filter collector that, for all specified operations with metal, is preceded by a mechanical pre-cleaner?
  Do you own or operate equipment used for any of the following metal treatment processes if the process emissions are only released into the general in-plant environment:
  • Surface Treatment
  • Pickling
  • Acid Dripping
  • Cleaning
  • Etching
  • Electropolishing
  • Electrolytic Stripping or Electrolytic Plating
This equipment may be exempt pursuant to Rule 285(2)(l).   This equipment may be exempt pursuant to Rule 285(2)(vi).   This equipment may be exempt pursuant to Rule 285(2)(r).


There are two additional PTI exemption options that may be available for you to use on emission units at your facility, and those are Rule 290 and Rule 291. Rule 290 exempts an emission unit with limited emissions from the requirement to obtain a PTI. Additional guidance on the use and applicability of the Rule 290 exemption can be found in the Rule 290 Guidance document. Finally, Rule 291 exempts an emission unit with de minimis emissions. Please refer to Rule 291 for details on how to utilize this rule.

Control Equipment: Scrubber

To be eligible for a specific PTI Exemption listed in Rule 280-291, any owner or operator of an exempt process or exempt process equipment must be able to provide information demonstrating the applicability of the exemption as specified in Rule 278a.

If you determine that a PTI is needed, the AQD has additional guidance available for the Metal Finishing Industry that includes information that would need to be included in a PTI application. The guidance is called "Information For Technical Review - Surface Treatment Processes." This guidance specifies exactly what information is required when submitting a PTI application for review for plating, pickling, etching, and cleaning operations. Additionally, the AQD also has guidance for air pollution control equipment, including scrubbers which are frequently utilized in the Metal Finishing Industry. The guidance is called "Additional Technical Information for Control Equipment: Scrubber."

Federal Regulation - Plating and Polishing NESHAP

On June 12, 2008, the USEPA issued final national air toxics standards for smaller-emitting sources, known as area sources, in the plating and polishing industry. These requirements apply to existing and new area sources and include plating and polishing tanks, dry mechanical polishing operations, and thermal spraying operations that use or emit compounds of one or more of the following metal toxic air pollutants: cadmium, chromium, lead, manganese, and nickel. The final rule includes management practices such as the use of wetting agent/fume suppressants. It requires equipment standards such as the use of tank covers or control devices, and the capture and control of emissions from thermal spraying and dry mechanical polishing. The USEPA amended this final rule in September 2011 to clarify certain aspects of the 2008 rule. The Plating and Polishing Area Source NESHAP is codified in 40 CFR Part 63, Subpart WWWWWW. As of 2020, Michigan has not accepted delegated authority for this NESHAP and, therefore, our inspectors do not determine compliance with the established requirements.

EGLE Industrial Pretreatment Program PFAS Initiative

In February 2018, a special effort under the National Pollutant Discharge Elimination System (NPDES) program, EGLE Water Resources Division (WRD) launched the Industrial Pretreatment Program (IPP) Per- and Polyfluoroalkyl Substances (PFAS) Initiative. This initiative aims to reduce and eliminate certain PFAS from industrial sources which are commonly found at Metal Finishing Industry operations that may pass through municipal wastewater treatment plants and enter lakes and streams, potentially causing fish consumption advisories or polluting public drinking water supplies. Additional information on the EGLE IPP PFAS Initiative, can be found on the Water Resources Division website.

MIOSHA Information

The Michigan Occupational Safety and Health Administration (MIOSHA) has informative fact sheets that may be useful for the Metal Finishing Industry.

For additional information, contact the MIOSHA Consultation Education and Training (CET) program.

Questions About the Metal Finishing Industry

Workers at a metal finishing facility

The Metal Finishing Industry and the air permitting rules can be challenging to work through. If you have any questions, feel free to call your district office and speak to the inspector for your facility. For other air quality related questions, contact the Environmental Assistance Center at 800-662-9278 and ask to speak to an Air Quality Specialist.





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