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In Indiana and across the country, pollution from diesel engines is a growing concern. The familiar black soot from buses and trucks contaminates our air and dirties our cities. Diesel exhaust is more than just a foul smell or visual nuisance; it is a detriment to public health. Numerous scientific studies have shown that exposure to the pollution from diesel exhaust increases risk for several serious health problems, including respiratory illness and cancer. However, diesel engines are a durable and economical source of power and are important to our economy. Through DieselWise, the Indiana Department of Environmental Management (IDEM) is working on projects to reduce harmful tailpipe emissions from diesel-powered vehicles. Following is funding activity.

2022 DieselWise Indiana with Volkswagen DERA Option Request for Proposals

Technology, Fuel, and Idle Reduction Alternatives for Fleets and Equipment

IDEM’s Retrofit Technology and Strategies page details various devices being utilized to reduce pollutants, smoke, and odor from diesel engines and improve the working environment for those operating diesel-powered equipment. Examples include replacements and upgrades such as diesel oxidation catalysts (DOCs), diesel particulate filters (DPFs), aftermarket auxiliary heaters, engine repowers, engine upgrades, aerodynamic technologies, low rolling resistance tires, and U.S. EPA verified technology.

Options for pollutant reductions also include fuel alternatives such as ethanol, biodiesel, compressed natural gas, propane/liquefied petroleum gas, and ultra-low sulfur diesel, as discussed on IDEM’s Fuel Alternatives and Options page.

IDEM’s Idle Reduction Alternatives page describes the benefits of reduced idling for companies and drivers and technology including automatic engine shut down/start up, direct fired heaters, auxiliary power units/generator sets, and advanced truck stop electrification systems.

School Bus Idling Initiatives

In partnership with the School Transportation Association of Indiana (STAI), IDEM introduced a voluntary idle reduction program that can be implemented in school systems statewide. IDEM’s Public and School Transportation page explains how school bus idling affects students and drivers and provides several actions that drivers, fleet operators, and schools can take to protect the health of students and drivers. STAI adopted a School Bus Idling Policy and School Bus Idling Policy Resolution aimed at protecting student passengers and bus drivers, reducing pollutants that contribute to ground-level ozone pollution, reducing fine particulate matter pollution, and reducing costs for fuel and maintenance. The DieselWise Idling page dispels myths about idling and provides free, downloadable graphics for schools, businesses, and municipalities to use to raise awareness about school bus idling programs and idle-free clean air zones.


The advancement of cleaner diesel fuel, engine and retrofit technologies helps Indiana thrive economically, while improving air quality. Indiana actively participates in United States Environmental Protection Agency’s Midwest Clean Diesel Initiative (MCDI) with other federal and state agencies, local communities, nonprofit organizations, and private companies in Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin. South Shore Clean Cities, Inc., IDEM’s co-lead representing Indiana in the MCDI, promotes affordable domestic transportation fuels, energy efficient mobility systems, and other fuel-saving technologies and practices throughout the state as Indiana’s designated representative in the United States Department of Energy’s nationwide “Clean Cities Coalition”.

Keep in mind, there are many things you can do individually as well! If you have a diesel vehicle, avoid idling. Turn your engine off when you are stopped. Keep your diesel vehicle well-tuned and maintained. When purchasing a diesel vehicle, purchase one that meets or exceeds U.S. EPA’s new emissions standards ahead of schedule.

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