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TO:                 Superintendents of Schools


FROM:          Martha G. Kirkpatrick, Commissioner, Environmental Protection

                        J. Duke Albanese, Commissioner, Education


SUBJECT:     Diesel School Bus Emissions


DATE:            May 23, 2002


May is Asthma Awareness Month and the Department of Education and the Department of Environmental Protection are writing to you about the adverse health risks posed by exposure to vehicular exhaust. Vehicle emissions contribute to air quality problems and can also cause serious health problems. 


Our agencies want to protect school children and bus drivers against excessive exposure to exhaust emissions and to improve air quality.  We are asking you to talk with your transportation supervisors and school bus drivers and encourage them to reduce idling time. This is especially important when buses are lined up in front of the school loading and unloading students.


Numerous scientific studies indicate that prolonged exposure to diesel exhaust can cause respiratory problems such as asthma and bronchitis, lung damage and even premature death. Children are more sensitive to air pollution because their lungs are not fully developed.  Their higher rates of respiration may lead to higher levels of exposure. According to a recent survey conducted by the Centers for Disease Control, Maine has one of the highest incidences of asthma in the nation.


Researchers from Yale University have linked increased exposure to diesel exhaust directly to idling school buses.  Fine particulate concentrations measured on buses in their study were 5 to 10 times higher than background levels.  School bus drivers can help reduce these levels, by limiting engine idling whenever practical.  Furthermore, limiting idling will save fuel, reduce engine wear and tear, and reduce transportation operating costs.


The attached fact sheet provided by the U. S. Environmental Protection Agency (EPA) outlines steps you can take to limit exposure to vehicle emissions.  In addition to anti-idling, another important strategy is to purchase new buses with lower emissions.  By October 1, 2002, seven of the largest diesel engine manufacturers are required by EPA to produce an engine that is 50 percent cleaner than current technology.  We recommend that school districts request these cleaner engines when making their bus purchases. Turning the fleet over more rapidly to take advantage of cleaner technology provides one way to achieve the maximum emission reduction benefit.


Another option you could consider is to use ultra-low sulfur diesel fuel in combination with pollution control devices known as particulate matter filters in all school buses.  This technology can reduce particulate emissions by more than 90 percent.  More information about diesel retrofit options is available on EPA’s web site .


We hope your school district will adopt some of these strategies and join us in our efforts to protect school children and improve air quality.  We encourage you to communicate your support for this initiative through newsletters and school board meetings.  The EPA and Maine’s DEP can provide outreach materials to assist you.  The Maine DEP is preparing a tips sheet and “anti-idling” magnets for bus drivers and will make them available to you upon request.   In addition, the Maine Association for Pupil Transportation (MAPT) is in support of this effort and can also provide assistance in developing your local strategy and policies. 


For more information or assistance, please have your transportation supervisors contact Lynne Cayting at the Maine Department of Environmental Protection at (207)-287-2437 or Harvey Boatman at the Department of Education at (207)-624-6884.  The contact phone number for MAPT is (207)-874-0622.







Attachment: EPA Diesel Fact Sheet published by the US Environmental Protection Agency--Air Pollution and Kids. What you should know about Diesel Exhaust and School Bus Idling <


The attachment above is in PDF format and requires Adobe Acrobat Reader to access it.  Adobe Reader is free and can be downloaded by clicking on the following link Get Acrobat Reader <>.  or you may contact Harvey Boatman at the Department of Education at 207-624-6884 to request a paper copy.