The Airborne Toxic Control Measure (ATCM) regulates particulate matter (PM) from portable diesel engines rated 50 horsepower and greater. For applicability and exemptions, review the regulation text. The ATCM reduces PM by the removal of tier 0 engines, restricting older engines from entering California and imposing fleet emission reduction requirements.
This regulation splits portable engine fleets into two sizes:
The following table outlines the required tier phase out schedule for small and large fleets.
|Tier Phase-out Schedule
(required for small fleets, default option for large fleets)
|Engine Certification||Engines Rated 50 - 750 bhp||Engines rated over 750 bhp|
|Large Fleet||Small Fleet|
|Tier 2 built prior to 1/1/2009||1/1/2022||1/1/2023||1/1/2025|
|Tier 2 built on or after 1/1/2009||NA||NA||1/1/2027|
|Tier 3 built prior to 1/1/2009||1/1/2025||1/1/2027||NA|
|Tier 3 built on or after 1/1/2009||1/1/2027||1/1/2029||NA|
|Tier 1, 2, and 3 flexibility engines||December 31 of the years after the date of manufacture. This provision shall not apply to any engine operation before the effective date of this regulation.|
|Fleet Average Standards
(option for large fleets only)
|Compliance Date||Fleet PM Stanard (g/bhp-hr)|
June 30, 2019 – Deadline for large portable engine fleets to request the Fleet Average Standards compliance pathway.
January 1, 2020 – Tier 1 portable engines, rated equal to or less than 750 bhp, must be phased out.
January 1, 2022 – For large fleets only: Tier 2 portable engines, rated equal to or less than 750 bhp and built on or after 1/1/09, must be phased out.January 1, 2022 – Tier 1 portable engines rated greater than 750 bhp, must be phased out.