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Children's Exposures to Diesel Exhaust


  1. Prohibit Bus Idling: Drivers should be required to turn off bus engines immediately upon reaching their destinations. Buses should not be turned on until fully loaded. This is especially important when buses are queued while loading and unloading at schools and transfer stations. Exceptions should include conditions that would compro m i s e passenger safety—e.g., extreme weather conditions, idling in traffic. In cases where engine operation is necessary to activate safety equipment such as flashing lights, buses should be retrofitted to permit battery operation. Idling restrictions should be defined by state statute and include clear and substantial enforcement power, instead of the present Department of Environmental Protection regulation 22a-174-18 (a)(5).
  2. Retrofit Diesel Buses to Lower Emissions: Diesel school buses should be refitted with particle traps and catalytic converters designed to reduce emissions. Retrofit of the existing fleet should be completed by 2003. 
  3. Require School Buses to Use Ultra Low Sulfur Fuels: Ultra low sulfur diesel fuel (<15 ppm) should be required for all school buses. Acid aerosols, ozone precursors, and fine particulate emissions would be substantially reduced in the vicinity of children.
  4. Replace Bus Fleet With Low Emission Vehicles: Existing diesel fleets should eventually be replaced with new low emission vehicles.
  5. Allocate the Cleanest Buses to the Longest Routes: Bus companies and towns should allocate buses with the lowest emissions to the longest routes. Meeting this recommendation requires emissions testing to distinguish between clean and dirty buses.
  6. Set Priorities: Priority for replacement with low emission vehicles, retrofit technologies, and filtration equipment should be assigned to communities with the highest ambient pollution levels, and to bus routes with the highest traffic intensity within communities.
  7. Limit Ride Duration: School districts should reduce students’ exposure to air pollution by limiting time spent on buses. This is already regulated by some town policies. Limiting ride duration would reduce exposure to pollution generated by diesel buses, and by other traffic.
  8. Require Routine Maintenance: Buses should be monitored and maintained to ensure that emissions remain at their lowest possible level. Special care should be taken to ensure that exhaust systems are fully intact and secure, and that engine compartments are completely sealed from interior passenger space.
  9. Test Tailpipe Emissions: Tailpipe emissions should be routinely tested on all school buses. This should be required by federal regulation, and implemented by the State.
  10. Establish Passenger Cabin Air Quality Standards: The federal government should establish standards for air quality within vehicles that provide assurance of health protection for children.
  11. Require Filtration Equipment: The federal government should require the installation of air filtration equipment on school buses. Equipment should be capable of removing vehicle exhaust from air entering the passenger cabin. This is especially important when buses travel in areas with high traffic intensity, or high outdoor background concentrations of pollutants.
  12. Adjust Federal Air Quality Standards to Account for Indoor and Vehicle Exposures: EPA should adjust outdoor air quality standards to better account for probable indoor and within-vehicle exposures to air pollution. The Clean Air Act demands that standards be set to provide “an adequate margin of safety,” however governments’ neglect of particulate levels within homes, schools, and vehicles make it impossible to conclude that standards protect health.
  13. Expand PM2.5 Monitoring Network: The State of Connecticut should expand its monitoring network to more fully capture the local variability of air pollutants.

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