DEEP: DEP Presents Diesel Emission Reduction Strategy

January 24, 2006

DEP Presents Diesel Emission Reduction Strategy to General Assembly

Report looks at buses, construction equipment and other options

The Connecticut Department of Environmental Protection (DEP) has outlined measures for consideration by the General Assembly that would significantly reduce harmful diesel emissions from buses and construction equipment. DEP also suggested other steps that could provide cost-effective approaches to improving the state’s air quality.

The DEP analysis of pollution caused by diesel emissions and particulate matter is contained in a Clean Diesel Plan presented this week to the legislature’s Environment Committee. The plan was developed in response to Special Act 05-7 of the General Assembly which required DEP to provide the legislature with a strategy to reduce health risks associated with diesel emissions.

The DEP concluded it would cost approximately $20 million to retrofit or replace transit buses, school buses and construction equipment to meet the specific targets for diesel emissions reductions suggested in the 2005 legislation. These targets were:

  • Transit buses: 85 percent reduction of diesel particulate matter by December 31, 2010;
  • School buses: maximize the reduction of diesel particulate matter emissions and prevent diesel emissions from entering the passenger cabin of the buses by December 31, 2010;
  • Construction equipment: maximize the reduction of particulate matter emissions servicing state construction projects valued at more than $5 million by July 1, 2006. (Note: the Department of Transportation has already implemented this type of requirement.)

The DEP report suggests the legislature consider steps to reduce diesel emissions in areas beyond the "mobile sources" specified in its Special Act of 2005. These include:

  • Consider the use of low sulfur and bio-diesel blended home heating oil

Reducing the permitted sulfur content of heating oil from 3,000 parts per million (ppm) to 500 ppm would reduce sulfur emissions - which contribute to fine particulate matter (PM 2.5) in the air - by 83 percent. "Emission reductions of this magnitude for a single source category are extraordinary," the DEP report says. The agency also said further reductions could be obtained by requiring a blend of low-sulfur heating oil and bio-diesel fuel. DEP also noted that this type of fuel is available and that any cost increase would be offset by lower boiler and furnace maintenance costs as a result of burning a cleaner fuel.

  • Address emissions from wood burning

Wood burning includes emissions from fireplaces, wood stoves and outdoor wood burning furnaces as well as open burning.. While not directly related to diesel emissions, wood burning is a major source of the type of particulate pollution addressed by the Special Act, representing an estimated 38 percent of fine particulate matter (PM 2.5) in the state’s air. As fuel prices rise, more people are burning wood as a primary source of fuel.

  • Develop a more comprehensive anti-idling strategy

Exposure to diesel pollutants, especially in urban areas, is exacerbated when diesel powered vehicles idle excessively. This poses serious health risks, especially for children, the elderly, and other sensitive groups. Excessive idling is also a waste of fuel. While there are anti-idling laws for school buses, broader legislative and legal enforcement action – including strong penalties for violations – is needed to reduce excessive idling by all types of motor vehicles.

  • Encourage fleet turnover

Beginning with the 2007 model year, all new heavy-duty diesel engines will be required to meet federal emission standards that are more stringent than the emissions reductions recommended in Special Act 05-7. This requirement will help reduce diesel emissions – as well as other pollutants that contribute to unhealthy ozone levels –as the operators of public transit and school bus fleets replace older vehicles. Tax incentives could be considered to encourage the earlier retirement and replacement of older buses, which would speed up air quality benefits of the new engines.

DEP Commissioner Gina McCarthy said, "Our agency worked closely with representatives from environmental advocacy groups, local public health agencies, business and industry, municipal and state governments, and other concerned citizens to address the issue of diesel emissions. Our report represents the wide range of viewpoints developed by all interested parties."

"Addressing diesel pollution is a priority for DEP and we will continue our efforts in this regard. The added value of our report," Commissioner McCarthy said, "will enable this session of the General Assembly to consider all possible options to address critical air quality and related public health issues. DEP looks forward to working with the legislature to help our state adopt a strategy that provides the most significant level of diesel emission reductions for every dollar we invest in this effort."

Robert W. Varney, regional administrator of the Environmental Protection Agency’s (EPA) New England office, said,  "Fine particles in diesel exhaust pose a significant threat to public health, especially to those suffering from asthma or other serious health problems. Connecticut’s Clean Diesel Plan is a multi-faceted strategy for reducing these emissions across the state, helping to significantly reduce diesel emissions statewide.  This plan will help improve air quality and protect public health in Connecticut, and is a model for other states."

Diesel Emissions Background

Emissions from diesel engines contain fine particulate matter – known as PM2.5. Exposure to PM2.5 has been linked to premature death from heart or lung disease. When inhaled into the lungs it can aggravate existing heart and lung diseases to cause cardiovascular symptoms, arrhythmias, heart attacks, chronic obstructive pulmonary disease, asthma attacks and bronchitis. EPA has also classified Diesel Particulate Matter as a probable human carcinogen.

Children, the elderly, and other sensitive populations are most at risk from diesel emissions and PM2.5. Urban areas, with construction sites and heavy traffic that includes buses and diesel trucks, are often "hot spots" for PM2.5, which puts large numbers of people at risk.

Public exposure to PM2.5 is a health issue in Connecticut and states across the country. The EPA has formally designated New Haven and Fairfield Counties as being in non-attainment with the federal ambient air quality standard for PM2.5.

Approximately one half of the state's population (1.73 million people) resides in these two counties. In addition, the entire state fails to meet federal ozone standards.

For more information on the Connecticut Diesel Reduction Initiatives and to review a full copy of the plan visit the DEP website at