Air quality regulations

Diesel engine emissions have far-reaching effects on the air quality of the surrounding environment. To improve the environment and stop these emissions from endangering human health and safety, several government-driven air quality regulations have been put into place at both the federal and state level.

The Clean Air Act, enforced by the Environmental Protection Agency (EPA), is our most influential air quality law, requiring compliance throughout the US. California sets even stricter air quality standards and is overseen by the California Air Resources Board (CARB).

The EPA and the Clean Air Act

How does the Clean Air Act regulate diesel particulate emissions?

  • The US Environmental Protection Agency has determined that diesel particulates are harmful carcinogens that contribute significantly to poor air quality and serious health issues.
  • The Clean Air Act sets air quality regulations requiring most diesel engines to reduce their overall levels of emissions of pollutants, which include diesel particulates.
  • As required by the Clean Air Act, the EPA sets National Ambient Air Quality Standards (NAAQS) for pollutants. States are required to develop plans to reach and maintain the NAAQS.

How do diesel particulate filters (DPFs) boost Clean Air Act compliance?

Up to 95% particulate emission reduction

DPFs applied to new and older engines reduce harmful diesel particulate emissions up to 95%, allowing operators to run diesel-powered equipment in full compliance with regulations.

NOx emission control technology

Beginning with the 2007 model year, 100% of on-road diesel heavy-duty engines required the use of a DPF, and 50% of the engines required nitrous oxide (NOx) emission control technology. Beginning with the 2010 model year, 100% of the on-road heavy-duty diesel engines required NOx emission control technology.

What are EPA emission standards for tiers 1,2,3, and 4?

Tiered progression

The EPA structured the 1998 nonroad engine regulations for engines over 37 kW (50 hp) as a tiered progression, phasing-in increasingly stricter standards between 1996 and 2008.

Tier 4 requirements

EPA tier 4 emission requirements for engines used for on-highway transport and power gen were phased-in from 2008 to 2015 with the goal of controlling NOx emissions and significantly reducing particulate matter (PM) emissions.

Driving advanced technologies

EPA tier 4 emission requirements drove advanced engine technologies for new engines and filters, such as Rypos’ active DPFs, which capture particulate matter and reduce emissions up to 95% to achieve tier 4 compliance.

Rypos active DPFs

Rypos active DPFs are self-cleaning, making them a simple, low-maintenance way to achieve tier 4 PM compliance for both new and older diesel engines.

CARB compliance

What is CARB compliance?

California Air Resources Board

The California Air Resources Board enforces the most protective air quality regulations in the country, affecting vehicles and equipment that operate and travel through the state.

Regulatory programs

The CARB enforcement policy is tough, but critical for public health benefits. You can face penalties of $5,000 to $10,000 per violation per day if inspectors stop your vehicle and issue a citation.

CARB enforcement

CARB has more than 50 regulatory programs impacting stationary and mobile sources. CARB compliance requires that Tier 1, Tier 2, or Tier 3 PM diesel emission levels be ⋜ 0.2 g/brake horsepower/hour. Trucks and trailers with transport refrigeration units (TRUs) that are 7 or more years old must meet CARB’s in-use PM performance standards.

Rypos is CARB verified

CARB verifies Rypos Active Diesel Particulate Filter emissions filtration systems for reducing diesel engine emissions of particulate matter, carbon monoxide, NO2, and hydrocarbons for compliance with CARB Tier 3+ emission standards.

Bay Area Air Quality Management District (BAAQMD) Tier 4 requirements

San Francisco Bay

The California Legislature created the Air District in 1955 to regulate stationary sources of air pollution in the nine counties surrounding San Francisco Bay.

Regulation 2, Rule 2

Under BAAQMD’s new source review (Regulation 2, Rule 2), new or modified sources with a potential to emit more than 10 pounds per day of any pollutant must install Best Available Control Technology (BACT).


BAAQMD requires BACT to be more stringent than what is achieved in practice for a type of source or what is technologically feasible and cost-effective.

Tier 4 genset requirements

Diesel generator sets in the BAAQMD district that are above 1,000 hp must meet EPA tier 4 requirements for both NOx and PM.

South Coast Air Quality Management District (SCAQMD) Requirements

Regulatory agency

SCAQMD is the regulatory agency responsible for improving air quality for the most population-dense region of the state, which is home to more than 17 million people.

Pollution from stationary sources

About 25% of this area's ozone-forming air pollution comes from stationary sources, both businesses and residences, which are regulated by SCAQMD.

Tier 4 genset regulations

Any diesel gensets in the SCAQMD above 1,000 hp and operating in a designated EPA Title V zone must meet tier 4 requirements for both NOx and PM.

Meeting EPA and CARB compliance

The Rypos solution

EPA- and CARB compliance can be met without sacrificing diesel engine performance. Our proven and reliable EPA-compliant and CARB-verified active DPFs remove up to 95% of diesel particulate matter from engine emissions without affecting engine performance. This instantly helps diesel engines achieve compliance and has an immediate on air quality.

  • Total particulate matter reduction up to 95%
  • Reduces hydrocarbons, carbon monoxide, and NO2
  • Active filter regeneration independent of exhaust gas temperatures
  • Low back pressure maximizes engine performance

Contact us

Get in touch

Contact us to learn more about how reducing black carbon emissions with Rypos active diesel particulate filters can improve air quality and achieve CARB compliance for your diesel-powered equipment.