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Diesel Emissions

Diesel engines have been and will likely continue to be a vital workhorse of our economy, powering large trucks, busses, farm, railroad, marine and construction equipment. However, diesel engine exhaust contains harmful pollutants in a complex mixture of gases and particulates. We are all potentially exposed to pollution from diesel vehicles. Reducing pollution from heavy-duty trucks and buses is part of the nation's clear air plan. Steps are being taken in Pennsylvania and nationwide to make this equipment less polluting.

Retrofit Your Fleet

Diesel Retrofit Information
Technology, funding and fleets that are moving ahead!

Reduce Idling

Diesel Idling Information
Trucks and buses waste fuel and create emissions from unnecessary idling. Improved management and technology can cut unnecessary idling.

Local Initiatives

Philadelphia Diesel Difference
A coalition of diverse partners with a mutual interest in reducing air pollution from diesel engines in the greater Philadelphia area.

Reducing Pollution from Diesel Engines in Pittsburgh Yesterday, Today and for the Future (PDF)
Come celebrate Pittsburgh's progress to reduce diesel emissions and chart our next steps to reduce diesel pollution

Regional Initiatives

The Mid-Atlantic Regional Air Management Association (MARAMA) and U.S. EPA Region III have established the Mid-Atlantic Diesel Collaborative, a new regional effort to reduce diesel related emissions. Pennsylvania invites the participation of fleet operators of all kinds, local governments, equipment vendors and distributors and others interested in reducing diesel emissions.

Regulatory Information


Rules have been developed by EPA for the first phase of a two-part strategy to significantly reduce harmful diesel emissions from heavy-duty trucks and buses, as well as, new quality requirements for diesel fuel to enable the use of a new generation of emission control technologies for diesel engines.


Pennsylvania requires heavy-duty highway diesel engines sold in the Commonwealth to have California Certification. This is applicable to model year 2005 and subsequent model years.