We have all seen that black puff of diesel smoke coming from a bulldozer or dump truck as it moves about the construction site. While diesel engines provide the power needed to keep our communities running, the exhaust from these workhorses contains pollutants that negatively affect public health and the environment. Fortunately, there are many cost-effective options that can let us harness the power of these engines without compromising clean air and public health. 

Diesel Emissions and Public Health

Reducing emissions from diesel engines is one of the most important air quality challenges facing the nation. Many scientific studies have linked diesel pollution-which contributes to particulate matter (PM or soot), ground-level ozone (smog) and air toxics-to a number of serious respiratory and cardiac health effects. These include heart and lung disease, chronic bronchitis, exacerbations of asthma symptoms and premature deaths. The U.S. Environmental Protection Agency has classified diesel exhaust as likely to be a carcinogenic.

While this is an important issue in the construction sector, the majority of construction companies are small businesses with twenty or fewer employees and might not have the ability to spend significant amounts of money to reduce emissions from their existing equipment. Fortunately, there are a variety of operating practices that companies can employ at low cost. In many cases, strategies such as reduced idling or better preventive maintenance can help lower operating costs while also reducing emissions. Companies that voluntarily participate in programs to improve the environment and reduce air emissions also benefit from an improved public image and better community relations.

Operating Strategies

Strategies are available that cost little to nothing to implement and can help improve the air quality at a construction site. Operating strategies can also help extend equipment life, which will ultimately save the business owner money. These include idle reduction and engine preventive maintenance. 

Idle Reduction

Elimination of unnecessary idling can save fuel, prolong engine life and reduce emissions. Unnecessary idling occurs when trucks wait for extended periods of time to load or unload materials or supplies or when equipment is left on when it is not in operation.  Often workers idle equipment out of habit.

An idling engine does not generate enough heat to achieve proper combustion. As a result, deposits can build up on the piston and cylinder walls of the engine, contaminating the oil and creating friction that wears out engine components faster. 

Reducing idling lowers employee and public exposure to unhealthy emissions.  This can have an effect on employee health and productivity, as well as prolong equipment life. It also lowers costs by reducing the need for maintenance. 

Equipment might idle to run cab accessories, such as heating and air conditioning.  In this situation, auxiliary power units or direct-fired heaters can allow equipment operators to maintain a comfortable cab environment without idling the main engine. 

A contractor can implement a company idling policy as a low-cost solution. This can involve raising awareness among equipment operators and managers of how much unnecessary idling is costing the company and advising operators to turn off equipment that is not being used.  

Engine Preventive Maintenance

The objective of a preventive maintenance program is to keep heavy-duty diesel engines running at their original level of performance and reduce the need and cost of major maintenance work. An effective program should include a plan for managing each piece of equipment over its life-cycle. This requires both an inventory of the periodic maintenance requirements for each piece of equipment, as well as accurate measurements of the hours of use. Based on equipment usage tracking and maintenance requirements, companies can appropriately schedule preventive maintenance.

While preventive maintenance can pay for itself by avoiding major equipment failures, properly maintained equipment can also reduce fuel consumption and emissions. Basic maintenance, such has changing the oil filter and maintaining proper oil change intervals, can save fuel through maintaining the lubricating properties of oil. Delayed oil changes can also cause power losses, which translate into fuel economy losses.


Basic preventive maintenance requires that companies establish policies and procedures to identify the signs of equipment failure before they occur. Operators can reduce maintenance costs by being vigilant in identifying abnormal equipment operations. The incidence of equipment failures can be reduced by implementing a"no smoking" policy that seeks to fix smoking equipment before failure. Operators can be trained to identify equipment that is producing abnormal smoke in the exhaust gas. Smoking equipment can be flagged for further inspection and possible service. Typically, blue exhaust gas will indicate oil consumption under a low load operation. Black smoke is related to over-fueling when the engine is operating at full load and a high temperature. Black smoke might indicate that engine maintenance is required.

Fuel Options

Switching to a lower sulfur or alternative fuel such as biodiesel can help reduce emissions.

Ultra-Low Sulfur Diesel Fuel

Ultra-Low Sulfur Diesel (ULSD) is a refined, cleaner diesel fuel that can be used in any diesel engine. ULSD reduces maintenance costs and harmful emissions. Low Sulfur Diesel (LSD) fuel has a sulfur content of 16 to 500 parts per million (ppm), while ULSD has a sulfur content of just 15 ppm or less.  As of June 2007, the use of LSD fuel is required for non-road engines, and ULSD will be required starting in June 2010. ULSD is required in all highway vehicles as of October 2006.

The use of ULSD alone can reduce emissions of particulate matter (PM) by 5 to 10 percent. In addition, ULSD enables the use of advanced emission-control technology, such as diesel particulate filters to be installed in new engines or retrofitted in older engines. Using such devices in equipment reduces emissions of PM, as well as other pollutants.



Biodiesel is a renewable fuel made from domestically grown crops such as soybeans, cottonseed, peanuts and canola. Biodiesel can also be produced from recycled cooking grease. It is usually blended with petroleum diesel. B5 is a blend of 5 percent biodiesel and 95 percent petroleum diesel, while B20 contains 20 percent biodiesel and 80 percent petroleum diesel. Since biodiesel is not petroleum-based, biodiesel reduces our dependence on foreign oil and helps support our nation's farmers.

The price of biodiesel depends on the production process used, the distribution and blending costs and the feedstock employed. Prices thus vary among regions.

Biodiesel can provide lubricity and several other technical advantages, including longer equipment life, lower maintenance costs, less equipment downtime and protection against fuel injector and injection pump failure. For proper performance, biodiesel should be fuel-grade, meaning that it must meet the American Society of Testing and Materials (ASTM) D6751 standards.

The use of biodiesel can reduce PM, carbon monoxide and hydrocarbon emissions. The percent of reduction varies on the blend. EPA has a software tool that can calculate the percent reduction of emissions located at www.epa.gov/otaq/retrofit/techlist-biodiesel.htm.

An EPA analysis of existing data suggests vehicles using biodiesel could emit slightly more nitrogen oxide (NOx) (about 2 percent more for B20 and 10 percent more for pure biodiesel). Subsequent studies have yielded mixed results, with some showing small increases and others showing small decreases. EPA is aware of more recent additional data and is evaluating it. 

Available Funding Assistance

As the interest in clean diesel has grown, more money is becoming available. Congress has recognized the importance of clean diesel through new legislation. The Energy Policy Act of 2005 includes the Diesel Emissions Reduction Program, which authorizes grant funds to be distributed for clean diesel projects. The EPA is optimistic that Congress will begin appropriating funds for this program next fiscal year.   

Additionally, the 2005 transportation bill known as "SAFETEA-LU" includes language labeling diesel retrofits as a priority activity for using Congestion Mitigation and Air Quality (CMAQ) funds. CMAQ funds-distributed by the U.S. Department of Transportation-total at least $1.6 billion annually through 2009 and are administered through metropolitan planning organizations and/or state transportation agencies. 

Additional funding information and availability timelines can be found on EPA's National Clean Diesel Campaign website at www.epa.gov/cleandiesel or through any of the EPA's Regional Clean Diesel Collaboratives listed on the site.

Leading public and private fleet owners are reducing emissions from their equipment and vehicles. The National Clean Diesel Campaign is building momentum as we work collaboratively across broad interests and develop incentives to achieve these important public health benefits.


Construction Business Owner, July 2007