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Control Strategies Evaluation


As the lead air quality planning agency for the Denver Metro/North Front Range region, the RAQC is responsible for evaluating control strategies aimed at reducing emissions, particularly precursors to the formation of ozone – namely nitrogen oxides (NOX) and volatile organic compounds (VOC). It is the RAQC’s goal to implement strategies that will continue to decrease ozone levels and bring the area into compliance with federal ozone standards.

Strategies are identified are identified by stakeholders and are then evaluated by the RAQC’s Control Strategy committee based on the following criteria:

  • • Air Quality Benefit
  • • Estimated Costs
  • • Impacted Groups
  • • Environmental Justice
  • • Feasibility of Implementation
  • • Necessary Partnerships
  • • Time to Implement

Summary of historic ozone design values in the DM/NFR compared to federal standards, key years, and designations 

RAQC Committees and Stakeholder Process

Strategies are vetted through the RAQC’s Control Strategy committee which is comprised of a subset of the RAQC Board of Directors.  These committee meetings are open to public and are aimed at getting stakeholder input throughout the process.  Please visit the RAQC Committee Page for more information or sign-up to receive emails about upcoming meetings and relevant information.

Submit an Idea

If you  have an idea for an emission control strategy that you’d like the RAQC to investigate please fill out a suggestion form!

Control Strategies Being Evaluated 

A living list of strategies being evaluated are available here. Below are the ideas that have been presented in Control Strategy Committee meetings.

Diesel Inspection and Maintenance

This strategy aims to mitigate emissions from on road diesel engines by expanding the existing diesel inspection and maintenance (I/M) program. Possible expansions of the program could include testing of NOx and VOC or adding an On Board Diagnostic (OBD) assessment.

A preliminary analysis (October 2019) of this strategy is available for review.

Low-Emissions Diesel Fuel

This strategy aims to reduce emissions from heavy-duty diesel sources through the implementation of a low emissions diesel (LED) fuel standard. LED fuel is characterized as having a:

  • •Maximum aromatic hydrocarbon content of 10% by volume
  • •Minimum cetane number of 48


A preliminary analysis (October 2019) of this strategy is available for review.

Green Construction

This strategy aims to mitigate emissions associated with the construction through the establishment of Best Operational Practices and public bid processes for use by local governments that will encourage the use of Tier 3 or 4 equipment.

A preliminary analysis (October 2019) of this strategy is available for review.

Heavy-Duty Equipment Usage Restrictions

This strategy aims to reduce emissions from non-road sources by implementing usage restrictions on heavy-duty diesel equipment. These includes seasonal/episodic usage restrictions or tier type usage restrictions.

A preliminary analysis (October 2019) of this strategy is available for review.

Establishment of Air Quality Fund

Establish dedicated fund to develop and implement projects that will benefit air quality through the implementation of fees. Projects include:

  • • Emission Control Strategies
  • • Capital Investments in Clean Technology
  • • Elimination of older/dirtier equipment
  • • Enforcement measures


A preliminary analysis (October 2019) of this strategy is available for review.

Low RVP Fuels

RAQC, and other state government agencies, are working together to evaluate strategies aimed at reducing ozone precursor emissions through the analysis of changes to motor gasoline specifications. Currently, 7.8 psi RVP gasoline with a 1 psi ethanol waiver is used in the ozone nonattainment area.  A study was conducted in the spring of 2019 to determine the  potential impacts of switching to a more stringent gasoline formula.

A preliminary analysis (October 2019) of the strategy is available for review.

A copy of the study and additional information on the low RVP fuels strategy can be found here.

Indirect Source Rule

This strategy aims to mitigate emissions associated with the construction and operation of indirect sources. Indirect sources include facilities, structures, buildings, etc. which can reasonably be expected to cause or induce substantial mobile source activity that result in emissions of air pollutants that might reasonably be expected to interfere with the attainment and maintenance of the national ambient air quality standards.

A preliminary analysis  (December 2019) of the strategy is available for review.

Anti Idling Program

An anti-idling program expansion aims to reduce emissions associated with idling light-, medium-, and heavy-duty vehicles.

A preliminary analysis (December 2019) of the strategy is available for review.

Low Carbon Fuel Standard/Clean Fuel Program

A Low Carbon/Clean Fuel Standard would reduce carbon emissions from the transportation sector by regulating the carbon intensity of transportation fuels.

A preliminary analysis (December 2019) of the strategy is available for review.

Light Duty Inspection and Maintenance

This strategy aims to mitigate emissions from on-road light-duty vehicles by lowering the emission limits of the current inspection and maintenance (I/M) program. The Air Pollution Control Division conducted a study on projected emission reductions at different emission limits.

A preliminary analysis (January 2020) of this strategy is available for review.

Vehicle Electrification

Zero Emission Vehicles (ZEV) and the associated charging station infrastructure are a critical strategy in reducing emissions from light, medium and heavy-duty mobile sources. Strategies associated with expanding the use of ZEVs include expanding charging infrastructure, exchanging high emitters for electric vehicles, and electrifying tourism.

A preliminary analysis (January 2020) of this strategy is available for review.

Commuter Trip Reduction Program

A commuter trip reduction strategy would be aimed at lowering vehicle miles traveled in the nonattainment area by working with employers to mitigate the number of employees traveling to work in single occupancy vehicles.

A preliminary analysis (February 2020) of this strategy is available for review, as well as an overview of efforts already underway in the Denver Metro area.

Extended Ozone Outlook

This strategy would create an “extended ozone outlook” for the general public in the nonattainment area. Providing the general public with an extended outlook would all individuals additional time to plan out personal ozone limiting actions.

Additional information on this strategy is available for review.

Out of Area Vehicle Inspection

This strategy would increase public outreach regarding vehicle inspections to drivers outside the nonattainment area who frequently travel/commute to the nonattainment area.

A preliminary analysis (February 2020) of this strategy is available for review.

Motorized Boating Restrictions

This strategy aims to mitigate emissions associated with boating activities within the nonattainment area by limiting motorized boating on high ozone days.

A preliminary analysis (February 2020) of this strategy is available for review.

Control Strategies Currently Enacted

Clean Air Fleets

The Clean Air Fleets program, started in 2003, is a regional public-private initiative to educate on- and off-road diesel vehicle operators on how to voluntarily reduce diesel emissions while saving money. The program provides information on, and funding for, simple retrofit technologies and fuels to reduce emissions. The Clean Air Fleets website at provides the latest program information and provides resources on advances in diesel engines, emissions control, idling reduction technology, alternative fuels, engine and fuel standards, and much more.

Download the program overview

Simple Steps. Better Air.

Simple Steps. Better Air is a voluntary program lead by the RAQC.  It is administered in the Denver Metropolitan area and by the North Front Range Metropolitan Planning Organization (NFRMPO) in Larimer and Weld Counties.  The Simple Steps. Better Air program provides information and education about ozone pollution and strategies to address the creation of ozone pollution.

More information is available at

Mow Down Pollution

Mow Down Pollution is a voluntary program implemented by the RAQC.  Mow Down Pollution provides free recycling of gasoline–powered lawn mowers and reduced pricing on the purchase of new, cordless, electric lawn mowers. 

More information on the Mow Down Pollution program can be found at

Low/Zero Emission Vehicles

In response to Executive Order B 2018 006  and  Executive Order B 2019 002 the Air Quality Control Commission (AQCC) passed Regulation 20 – The Colorado Low Emission Automobile Regulation. The Regulation makes Colorado the 10th state to join California’s ZEV program.


APCD LEV Rulemaking (Approved Nov. 16, 2018)

APCD ZEV Rulemaking (Approve Aug. 16, 2019)


LEV/ZEV Overview (Jan. 2016 MS/F Committee Mtg, APCD)

Enhanced Inspection and Maintenance

Under the Clean Air Act, nonattainment areas classified as Moderate or higher are required to implement a motor vehicle inspection and maintenance (I/M) program as part of the State Implementation Plan.  To attain the carbon monoxide (CO) NAAQS, the Denver metropolitan area was required to implement an “enhanced” I/M Program. Colorado began implementing an enhanced program in 1995 and continues to implement it in the Denver metropolitan seven–county area, including Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, and Jefferson counties.  In 2010, parts of Larimer and Weld Counties in the North Front Range area were added to the program area as a State–Only requirement.

More information on the program is available on the Colorado Department of Public Health and Environment’s website.

Optical Gas Imaging Camera Loans

In 2011, the Regional Air Quality Council (RAQC) received a Supplemental Environmental Project (SEP) grant from the Colorado Department of Public Health and Environment (CDPHE) to acquire an OGI Camera for the purpose of loaning out to Qualified Users (i.e., industry representatives, local government, health department, and university staff) to identify and repair gas leaks primarily at oil and gas industry exploration and production facilities across Colorado.  In addition, the RAQC provides periodic training to potential Qualified Users to become level 1 certified, which enables individuals to borrow the camera for such activities.  The availability of this camera has been instrumental in the identification of hundreds of leaks in the Denver Metro/North Front Range nonattainment area and the RAQC plans to continue this program for the foreseeable future.

Low VOC AIM Coatings and Consumer Products

To address VOC emissions from consumer products and Architectural and Industrial Maintenance (AIM) coatings, the RAQC and the Colorado Air Pollution Control Division (APCD) investigated the feasibility of adopting model rules crafted by the  Ozone Transport Commission (OTC) based on California Air Resources Board (CARB) regulations. This was identified as a viable control strategy and was developed into a rulemaking. 

Regulation 21, the Low VOC Architectural and Industrial Maintenance (AIM) coatings and consumer products rule, was approved by the Air Quality Control Commission and will go into effect May 21st, 2020.

Additional information is available here.

Street Sanding/Sweeping

In conjunction with local and state street maintenance departments, the RAQC developed a street sanding program, which has achieved a weighted average region-wide emissions reduction of approximately 50% and has allowed us to comply with the PM10 federal standard since 1993. The Street Sanding Program was originally incorporated into the federally approved PM10 State Implementation Plan (SIP) as Air Quality Regulation No. 16 in 1993.  The Regulation was revised a number of times and was last updated by the State in 2000 for the 2001 PM10 SIP. Our challenge now is to maintain current street sanding practices in the face of increasing vehicle traffic and significant budget constraints in some jurisdictions.

Additional program information and related reports are available here.

Reasonably Available Control Technology

As a Moderate nonattainment area for ozone, the Denver Metro/North Front Range region is required by the Clean Air Act to implement Reasonably Available Control Technology (RACT) for all major sources within the nonattainment area.  For a Moderate area, major source is defined as a source that emits 100+ tons per year (tpy) of nitrogen oxides (NOX) or volatile organic compounds (VOC).  This threshold for what is considered a ‘major sources’ gets tighter as the region is reclassified to higher levels under the various ozone standards.  As a region on the cusp of becoming a Serious nonattainment area, the major sources threshold has the potential to go down to 50 tpy as soon as January 2020.  As a result, the Colorado Air Pollution Control Division (APCD, or Division) continues to work with stakeholders in developing RACT for major sources of NOx or VOCs in the Denver Metropolitan/North Front Range Moderate ozone nonattainment area.

Further Information

Colorado Air Pollution Control Division (APCD)


RACT for New Major Sources (May 2019)

Colorado’s MS RACT Efforts (Sept. 2017)