Independent Study Finds Donaldson Spiracle T Crankcase Filtration System Significantly Reduces Emissions Inside School Buses

MINNEAPOLIS (July 12, 2005) - An independent study conducted by the Clean Air Task Force (CATF) reported that a Donaldson Company, Inc. (NYSE: DCI ) Diesel Particulate Filter (DPF) combined with a Donaldson SpiracleT Crankcase Filtration system was found to significantly reduce crankcase emissions within a school bus cabin. A separate report by The Southern Alliance of Clean Energy also confirmed the CATF study results.

The purpose of the CATF study, which was conducted in partnership with Kids Against Pollution, measured diesel particulate matter, such as black carbon, along with carbon dioxide, carbon monoxide and other hazardous contaminants on school buses. The study specifically focused on how bus self-pollution affects air quality inside the school buses. This two-year project was part of a three-city study conducted by the CATF and partners in Chicago, Atlanta and Ann Arbor, MI.

The report states, "The Donaldson Spiracle was an inexpensive solution to control crankcase emissions." The Ann Arbor study results indicate that with the DPF muffler and the Spiracle retrofits together, particulate matter pollution from both the tailpipe and crankcase is significantly reduced inside the bus cabin. The DPF muffler reduces ultra-fine particles emitted from the tailpipe and Donaldson's Spiracle system reduces particulate matter from the engine crankcase. For additional information, contact Donaldson Company at 952- 887-3725 or visit the company's website at www.donaldsonexhaust.com .

The complete published report, A Safer Ride to School: How to Clean Up School Buses and Protect Our Children's Health , is at http://www.catf.us/publications/view/82 .
A separate report, School Buses: An Inside Look at Air Pollution, by The Southern Alliance of Clean Energy, which was based on data from the CATF study is at http://www.cleanenergy.org/schoolbusreport.cfm .

About Donaldson Company, Inc.

Donaldson is a leading worldwide provider of filtration systems and replacement parts. Donaldson is a technology-driven company committed to satisfying customer needs for filtration solutions through innovative research and development. Donaldson serves customers in the industrial and diesel engine markets including in-plant air cleaning, compressed air and gas purification, power generation, disk drive filtration, off-road equipment and trucks. Our 10,000 employees contribute to the company's success at over 30 manufacturing locations around the world. Donaldson is a member of the S&P MidCap 400 Index and Donaldson shares are traded on the NYSE under the symbol DCI . Additional company information is available at www.donaldson.com.