There has been much concern nationally about the potential harmful effects of particle emissions produced by older generations of diesel engines, including those that were used in school buses.

The 2002 Minnesota Legislature adopted a requirement that all operators of diesel school buses must minimize, to the extent practical, the idling of school bus engines and exposure of children to diesel exhaust fumes.

In conformance with the requirements of this statute and to reduce fuel consumption, the Specifications for Pupil Transportation section of the contract for transportation services between the School District and the District's bus contractors contains the following requirements that apply to school buses while on Saint Paul Public Schools route and field/athletic trip service:

Except as noted below, each school bus driver operating under this contract in temperatures above an ambient, or wind chill, temperature of twenty degrees Fahrenheit shall shut down his/her school bus no later than five minutes after arrival at the school. school sponsored activity, field/athletic trip stop or destination,

or layover point between trips in a route sequence. The five minutes of idle time is to allow the engine and turbo charger to cool prior to shutdown.

After starting an engine that has been shut down for over twenty minutes drivers may idle their engines for up to five minutes to allow the engine to warm-up prior to applying a load. Drivers operating in ambient, or wind chill, temperatures below twenty degrees Fahrenheit may idle engines as necessary to provide warmth to the driver and to prevent fuel gelling.

Drivers may idle buses as necessary in the following situations:

Lift buses loading or unloading multiple wheelchairs

School buses transporting medically fragile students who have been identified by the School District as needing continuous warmth even with ambient, or wind-chill, temperatures at or above 20 degrees Fahrenheit.

A vehicle experiencing mechanical problems which may not restart.

Vehicles parked as a shelter area for a field trip group involved in outside activities which must be kept warm to protect the students.

Other
emergency situations directed by the Transportation Department staff or their employer.

Each contractor is also required to provide training to all drivers operating under contract to the Saint Paul Public Schools explaining the requirements of Minnesota Statute 123B.885, the general concerns about school bus diesel emissions, and the requirements of the contract for transportation services with respect to school bus idling.

In October 1997, the EPA adopted new emission standards for the 2004 model year 2004 and later heavy-duty diesel truck and bus engines. These standards reflects the provisions of the Statement of Principles (SOP) signed in 1995 by the EPA, California ARB, and the manufacturers of heavy-duty diesel engines with the goal of drastically reducing NO_x emissions from highway heavy-duty engines.

All school buses used on Saint Paul Public Schools routes are powered by the new generation of electronic engines mandated by EPA standards since 1996. The average age of a bus on Saint Paul Public Schools route service is 5 years so approximately 50% conform to the

2004 or 2007 standards.

In 2000 the EPA mandated even stricter emission standards that came into effect for 2007 and later engines. These engines must operate in Ultra Low Sulfur Diesel fuel (ULSD) and approach a zero emission standard. Some of the highlights of the 2007 EPA Standard:

Nitrogen oxide (NOx) emissions must be reduced by more tha 50% over the 2004 emission standards.

Particle matter emissions must be reduced by 90% over the 2004 emission standards.

All diesel fuel sold for on the road use must be Ultra Low Sulfur Diesel Fuel (ULSD).

All 2007 engines operating on ULSD are required to use a new low-ash formulation engine oil. The low-ash oil will reduce particle emissions.

Most engine manufacturers have been using a diesel oxidation catalyst system in the exhaust system since introduction of the 2004 emission compliant engines. Most 2007 compliant engines will add a diesel particle filter to the exhaust system that captures particle matter (soot) from the exhaust.