Portable Equipment Registration Program (PERP)

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Portable Equipment Registration Program (PERP)

The Portable Equipment Registration Program (PERP) is a statewide program created by the California Air Resources Board (CARB) to register portable equipment as an alternative to securing permits from local air quality control districts. PERP registered equipment may operate throughout the state without obtaining permits to operate from any of California's 35 air quality management or air pollution control districts.

Generally portable engines over 50 hp and portable equipment units that emit particulate matter cannot be operated within the jurisdiction of the Mojave Desert Air Quality Management District (MDAQMD) without either an MDAQMD Permit to Operate, or PERP Registration. In some cases, portable equipment may be ineligible for PERP registration, leaving the MDAQMD permit as the only option.

Whether registered under PERP or permitted by MDAQMD, the responsibility for inspection of portable equipment and enforcement of applicable clean air requirements resides with MDAQMD.


Appointment Request Form - 45 day notification

District Notification - Equipment units at a location more than 5 days

What's New!

Changes to the PERP program are expected in the near future.  As soon as any changes are official updates will be posted.

Refer to CARB's website for more information.

MDAQMD Permit or PERP:

The most significant difference is that PERP allows the freedom to operate portable engines and portable equipment units throughout the state (with a few exceptions) without the need to obtain separate permits from each air quality district.  Highlights of each program are summarized in the table below.


PERP Registration

Renewal Cycle







Limited to MDAQMD

State of California

Residence Time

< 12 months

< 12 months



Set by CARB

Enforcement Agency



Inspection Frequency

Yearly unannounced

Arranged every 3years

For more information about the PERP Program, contact CARB at 916-324-5869 or visit website.


NOTICE:  Effective immediately, the California ARB will no longer accept PERP applications and renewal invoice payments via fax due to security issues with credit card numbers transmitted by this method.  Please mail them directly to the address listed on the application form and renewal invoice.

Ineligible for PERP and District Permit:

  • Engines used to propel mobile equipment or a motor vehicle of any kind
  • Engines less than 50 bhp
  • Tier 0 engines
  • Engines or equipment units  attached to a foundation
  • Engines or equipment units residing at the same location for more than 12 consecutive months
  • Equipment units and their associated engines determined by the Executive Officer to qualify as part of a stationary source permitted by a district
  • Portable engines or equipment units subject to an applicable federal Maximum Achievable Control Technology standard or National Emissions Standard for Hazardous Air Pollutants or federal New Source Performance Standard, except for equipment units subject to 40 CFR Part 60 Subpart OOO (Standards of Performance for Nonmetallic Mineral Processing Plants)
  • Generators used for power production into the grid except to maintain grid stability during an emergency event or other unforeseen event that affects grid stability
  • Generators used to provide primary or supplemental power to a building, facility, stationary source, or stationary equipment, except during unforeseen interruptions of electrical power from the serving utility; maintenance and repair operations; electrical upgrade operations that do not exceed 60 calendar days; operations where the voltage, frequency, or electrical current requirements can only be supplied by a portable generator; or remote operations where grid power is unavailable. For interruptions of electrical power, the operation of a registered generator including startup, shutdown, and testing shall not exceed the time of the actual interruption of power. 

For a complete description of eligibility requirements, refer to the CARB PERP website.

PERP Registration:

Registration Requirements: To register in PERP, all engines must meet the following tier levels:

  • Engines rated 50 to 75 bhp:  Interim Tier 4.
  • Engines rated 75 to 750 bhp:  Tier 3.
  • Engines rated over 750 bhp and over: Tier 2.

PERP Frequently Asked Questions

PERP Applications

Statewide Portable Equipment Registration Program website

Portable Engines:

Internal combustion engines are used to power a variety of portable equipment categories, including, but not limited to:

  • well drilling
  • barges
  • diesel pile-driving hammers
  • pumps
  • service or work-over rigs
  • cranes
  • welders
  • compressors
  • dredges
  • power generation
  • tactical support equipment (TSE)
  • wood chippers

Portable Equipment Units:

The California Air Resources Board (CARB) defines an equipment unit as "...equipment that emits PM10 over and above that emitted from an associated engine".

Except for a limited number of portable equipment unit categories that are ineligible for PERP Registration, any equipment unit may register under this regulation. Examples of portable equipment include, but are not limited to:

  • Portland concrete batch plants
  • sand & gravel screening
  • unheated pavement recycling & crushing operations
  • tub grinders & trammel screens
  • rock crushing
  • confined and unconfined abrasive blasting


    Generally, portable equipment units can be operated within the jurisdiction of the MDAQMD provided an MDAQMD Permit to Operate or PERP Registration has been issued for the equipment. 

    For a complete description of requirements for equipment units, refer to the CARB website

Scheduling a Portable Inspection:

 The MDAQMD may conduct inspections of any PERP registered equipment at any time in order to verify compliance with the applicable requirements.  In accordance with PERP Program requirements, the MDAQMD is required to inspect all PERP engines and equipment units for which the MDAQMD has been designated as the "home district":

  • within one year of the issuance or renewal of the registration; and
  • -on a three-year basis

The information below outlines the process to schedule an arranged inspection with the MDAQMD.

Provide Information to the MDAQMD:

 If a registered equipment unit will be at a location for more than five days, the owner or operator or renter…shall notify MDAQMD in writing, via facsimile, or by telephone, within two working days of commencing operations in the District.  To assist an online notification is also available:

Owners and operators of registered engines or equipment units are required to contact MDAQMD within 45 days of the initial issuance or renewal of a registration to arrange an inspection.

Download a PERP Appointment Request Form and submit the completed form by mail, or email to perp@mdaqmd.ca.gov.

MDAQMD will provide the contact specified in the request an arranged date and time of the inspection. This form must be signed and returned to the MDAQMD before the inspection can take place.


 In the event that an arranged inspection of a registered engine or registered equipment unit must be rescheduled due to unforeseen circumstances, the owner or operator is required to:

  • notify the MDAQMD of the cancellation no later than 72 hours prior to the scheduled inspection; and
  • reschedule the inspection no later than 90 days after the initially scheduled inspection.

Unreasonable Actions:

 The MDAQMD will make every reasonable effort to accommodate requested inspection dates; however, it is essential that the owner or operator put forth equal effort to ensure that the scheduled inspection occurs as planned.  This includes ensuring that the equipment identified in the inspection request is available at the location, on the date, and at the time specified in the request.  Further, if an "in-field" inspection has been arranged, the equipment must be in operation.

Any unreasonable actions on the part of the owner or operator that prevent the inspection from occurring within the specified time frame will be deemed a violation. Actions taken by the owner or operator that could be deemed "unreasonable" include, but are not limited to:

  • failing to respond to the district correspondences or other contracts made to schedule the inspection;
  • failing to ensure that the registered engine or equipment unit is in operation for arranged "in-field inspections," where the district has provided advance notification to the owner or operator that the registered engine or equipment unit is required to be observed in operation.

For more information about PERP inspections, contact the MDAQMD by phone at 760.245.1661 or perp@mdaqmd.ca.gov.