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  • Photo of school buses.
    The Northeast is one of the most densely populated regions in the United States and is home to two of the most populous metropolitan areas in the country – New York and Boston.
  • There are over 93,000 school buses in the eight-state region, ranging from pre-1990 to 2009 engine model years. Older school buses emit 54 times the nitrogen oxides (NOx) and 60 times the PM of 2007 or newer engine model year buses.

Reducing Diesel Emissions from Municipal Fleets

  • More than 4,000 diesel school buses across the region have been equipped with emissions control technology, including diesel oxidation catalysts, flow-through filters, and diesel particulate filters.
  • In addition, many retrofit programs also install closed crankcase ventilation (CCV) filters, which return gases to the engine's intake system. Crankcase particulate matter from an uncontrolled engine can comprise up to 25 percent of the total vehicle PM emissions.
  • All eight Northeast states have programs to reduce school bus idling.
  • In New York City, where emissions problems are the most severe, the New York City Sanitation Department has equipped 252 trucks with advanced emission control technology.
  • The city of Boston has installed advanced emissions controls on its diesel trolleys and is fueling its heavy equipment and diesel vehicles with a blend of at least 5% biodiesel and ultra-low sulfur diesel.
  • The Northeast Diesel Collaborative works to replicate these successful programs in smaller cities, develops partnerships with municipal and private fleet operators to install advanced emission control technologies, helps municipalities and other fleet owners to purchase heavy-duty diesel hybrid trucks, works on new legislation, and offers workshops to build awareness and support.

State and Local Regulations



  • Idling Regulation, Section 1 .38 MRSA 585-K, Idling Requirements for Motor Vehicles in Maine


  • School Bus Idling Regulation, Chapter 90. Section 16A, No person shall cause, suffer, allow or permit the unnecessary operation of the engine of a motor vehicle while said vehicle is stopped for a foreseeable period of time in excess of five minutes.

New Hampshire

New Jersey

  • New Jersey's Mandatory Diesel Retrofit Program requires emission controls on transit vehicles, publicly owned vehicles, and garbage trucks. It also requires installation of closed crankcase ventilation (CCV) filters on school buses plus a study of how tailpipe emissions on school buses impact the passenger compartment. If tailpipe emissions are found to be significant, then tailpipe emission controls (i.e., DOC, DPF) will be required. The law also empowers local police to enforce idling prohibitions.
  • Ballot Initiative passed November 8, 2005, allows use of funding generated from a state Corporate Business Tax to reimburse fleet owners for 100 percent of their retrofit costs over the next 10 years.
  • Idling Regulation, N.J.A.C. 7:27-14 (pdf) (82 KB) requires that diesel powered vehicles idle for no more than 3 minutes.

New York

New York City Local Laws
New York City has passed several progressive Local Laws that reduce diesel emissions from vehicles operating in the city including:

  • Local Law 38, 2005 – Relates to the city's purchase of cleaner motor vehicles
  • 15 RCNY § 15-01 – Reduces diesel emissions from the city's diesel-powered motor vehicles
  • Local Law 145, 2013 – Reduces diesel emissions from vehicles that handle solid waste and recyclable materials.
  • 15 RCNY § 25-0 – Reduces the emissions of pollutants from sight-seeing buses
  • 15 RCNY § 26-01 – Reduces emissions of pollutants from vehicles that transport children to and from school.
  • Local Law 77 (pdf) (38 KB) - Use of Ultra Low Sulfur Diesel Fuel by Nonroad Vehicles

Rhode Island


Related Resources

MassDEP's Community Strategies to Reduce Air Pollution and Climate Change (pdf) (5.5 MB)
This compilation of strategies to reduce air pollution and climate change is designed to assist communities in researching and assessing programs that have been effective in other communities. With an understanding that a variety of strategies can be employed in different communities with varying degrees of success, this document is not meant to be prescriptive but rather to spark interest and discussion resulting in decision-making at the local level that most effectively addresses local air pollution and climate change issues.

MassDEP's Idling Reduction Toolkit (pdf) (626 KB)
A number of promotional tools -- including fact sheets, letters, news releases, logos and signs - developed by MassDEP to help city, town and school officials launch vehicle idling reduction campaigns.

EPA Region 2: RARE Grant – Study of Emissions from Idling and Restart of School Buses
With funding from an EPA Regional Applied Research Effort (RARE) grant, Region 2 and the EPA Office of Research and Development (ORD) studied school bus exhaust emission levels during idling and restart scenarios. The study found that the emission pulse measured after the school bus is restarted contains less carbon monoxide, nitrogen oxides, and other pollutants than if the school bus idled continuously over a 10-minute period. The analysis indicated that continuous idling for more than three minutes emitted more fine particle (soot) emissions than at restart (View study results).