You may have heard that diesel emission standards are changing in 2007, and you probably said to yourself, “Who cares? Those ‘engineer types’ who work upstairs at the apparatus factory will figure it out!”

Yes, that is true. The “engineer types” are feverishly working on the problem, but it will affect just about every new apparatus manufactured after this year! It will likely change some cab configurations, maintenance, operations, and finally price.


Over the years, the Environmental Protection Agency (EPA) has been steadily requiring reductions in diesel exhaust emissions. Table 1 shows just how much reduction has taken place. The goal is to reduce in 2007 diesel pollution by 95 percent from pre-2004 models.

Table 1. EPA Standards for New Trucks and Buses

The two major components of diesel exhaust being targeted are nitrogen oxide gases, commonly referred to as NOX, and particulate matter, or soot. Nitrogen oxide gases readily form nitrogen dioxide in the environment, which is a major component of smog, acid rain, and ozone. In addition, crankcase emissions, referred to sometimes as “blow-by,” will now be regulated as exhaust emissions.

Some people feel that “we are the fire service and we should be exempt from these requirements!” No such exemption is offered. So for all intents and purposes, the engine in your pumper or aerial might just as well be powering an over-the-road truck or a transit bus.


Diesel engines very effectively convert the chemical energy contained in the fuel into mechanical power. Diesel fuel is injected under pressure into the engine cylinder where it mixes with air and the combustion occurs. The exhaust gases discharged from the engine contain several compounds that are harmful to human health and to the environment.

Nitrogen oxides (NOX) are generated from nitrogen and oxygen under the high pressure and temperature conditions in the engine cylinder. NOX consists mostly of nitric oxide (NO) and a small fraction of nitrogen dioxide (NO2). Nitrogen dioxide is very toxic. NOX emissions are also a serious environmental concern because of their role in the formation of smog.

Diesel particulate matter (DPM), as defined by the EPA regulations and sampling procedures, is a complex aggregate of solid and liquid material. Its origin is carbonaceous particles generated in the engine cylinder during combustion. The EPA reports that these fine particles of soot in the air are a serious public health problem because they easily pass through the nose and throat and lodge in the lungs. They can cause lung damage and lung cancer and aggravate respiratory conditions such as asthma and bronchitis. The fine particles from diesel engines also contribute to haze, which restricts our ability to see long distances, ozone formation (or smog), acid rain, and global climate change.

Sulfur dioxide (SO2) is generated from the sulfur present in diesel fuel. The concentration of SO2 in the exhaust gas depends highly on the sulfur content of the fuel. Sulfur dioxide is a colorless, toxic gas with a characteristic, irritating odor. Sulfur oxides have a profound impact on the environment and are the major cause of acid rains.


Diesel engine models in current production do not comply with the new standards. All engine manufacturers are making changes to their current designs or are designing new engines that will meet the 2007 standards. Some prototype engines have been delivered, but the apparatus manufacturers are eagerly awaiting the final version of the new designs so they can attempt to fit them into their current chassis line or possibly modify their cab configuration to meet the needs.

Reduction in sulfur dioxide pollution is being addressed by the EPA requirement that fuel manufacturers produce low-sulfur diesel fuel in 2006. In addition to reducing pollution, the lower sulfur content in the diesel fuel is necessary to enable the use of advanced emission controls that will be required on diesel engines to comply with the reduced NOX and particulate requirements.

NOX and diesel particulate matter need to be addressed in different and distinct ways. One way to reduce the NOX pollution is to recirculate the exhaust gas and reburn a portion of it. This currently is being done on most engines, but the degree of recirculation most likely will need to be increased. Other control methods include more efficient combustion controls, including fuel injection and airflow into the cylinders. This could have an effect on the diesel engine’s acceleration performance. A second less likely way to address the NOX problem is to chemically treat the exhaust with a compound known as urea. This would require a separate storage tank on the apparatus, and the chemical would have to be readily available for use. Although this is being pursued in Europe, it is not likely to be used to comply with the 2007 standards in America.

A combination muffler/particulate filter, with catalytic elements, installed in the exhaust system will process diesel particulate matter. As easy as this sounds, there are some significant complications when it comes to fire apparatus. First is the size of the filtering unit. Depending on the horsepower of the engine, the filter could be as long as four feet and more than a foot in diameter. Another consideration is its location. The filter’s operation will require retention and generation of heat in the exhaust system to regenerate or burn out the particulate matter and soot that accumulate. This could require that it be located very close to the engine’s exhaust manifold. This will also result in higher exhaust temperatures, which will lead to additional insulation and possibly protection in the area of exhaust discharge.

All vehicles will be required to have an onboard diagnostic system to monitor and control the performance of the engine’s emission system. In New Jersey, the Motor Vehicle Commission no longer performs tailpipe monitoring on all gasoline-powered vehicles when they report for periodic inspection. Modern vehicles, with onboard computer connections, have their history analyzed to detect malfunctions and polluting engines.


In the beginning of this article, I indicated that compliance with these new regulations could change configuration, maintenance, operation, and price. Let me explain each.

The current configuration of each manufacturer’s particular model of cab has an engine enclosure to fit the largest engine available in that particular chassis model. Engines are now likely to be larger or at least will require more space to incorporate the modifications necessary to meet the environmental regulation. This could mean wider or taller engine housings. In cabs already cramped for space, it could pose a significant problem, especially for the high horsepower requirements of heavier aerials or pumps with high gpm output. Cabs that undergo significant changes might have to be recertified to meet current crash test standards.

Another effect on cab design will be the available space for airflow cooling of the engine compartment. Recirculating hot exhaust gases increases the heat generated by the engine. This heat must be dissipated, or the engine could be destroyed. We already experienced larger radiator grilles and side venting on some models. It is possible that even larger radiators and fans might be necessary to eliminate the added heat. Blocking any portion of the radiator grille with mounted accessories such as hose trays and other features will probably be impossible. That might even include lift-up lids on hose trays that could impede the airflow.

Another question that comes to mind applies to the heat generated by other components and that is now dissipated by the radiator. The radiator cools hot automatic transmission fluid as well as additional heat generated by a hydraulic transmission retarder. Will the manufacturers need to find another way to expel this heat?

Another issue of heat is the routing of the exhaust pipe and muffler/exhaust filter. We are used to setting the pump, intake and discharge plumbing, valves, and so on and hanging the muffler after the fact, wherever it fits. If the muffler/filter needs to be close to the engine heat to regenerate, what effect will that have on the other components? Some estimate that the exhaust temperature may increase from 900°F to 1,200°F. Discharging exhaust at that temperature next to the apparatus at ground level could be a safety hazard and might have an adverse effect on exhaust-removal equipment mounted in the fire station.

The technical nature of fire apparatus maintenance has increased dramatically over the years. Gone are the days of making some throttle linkage adjustments for quicker pickup. The addition of pollution controls and electronic monitoring devices will certainly increase the level of expertise with which the maintenance department will need to comply.

Additional components will, of course, bring additional maintenance concerns, especially in newly designed engines that have not been “tested in battle.” It’s a very difficult decision to purchase the “first” of anything, let alone a piece of apparatus that needs to serve the community for 15 to 20 years.

The regeneration of the muffler/exhaust filter (burning out of excess soot) will possibly be accomplished by the heat of the engine if a high enough exhaust temperature is maintained. This might not be a problem for a fire company that responds for several miles at highway speed, but it could be difficult for a city or suburban unit that has a three-minute response to an EMS call and sits idling for 20 minutes. If the required emission-monitoring computer detects that the filter is becoming clogged, the engine might need to sit on the apron back at the station for a period of time running to burn out the soot. Under extreme conditions, or after a period of time, the filter most likely will need professional attention by a qualified service center.

With the heat-elimination situation of the hotter engines, maintenance of the cooling system will be essential. Keeping the radiator core clear of debris, checking for leaks, and maintaining the coolant level will all be critical.

Increased heating of the engine’s lubricating oil will also require strict adherence to the engine manufacturer’s recommended schedule of preventive maintenance.

As far as operations are concerned, we will most likely detect an element of reduced performance with the apparatus. Because of some of the previously discussed concerns, you may not be able to specify that 500 horsepower diesel in your typical city pumper.

If the apparatus is in a filter regeneration cycle, it will be out of service until the emission electronics determine that the filter is clear.

Finally, the price! Remember those “engineer types” who work upstairs? Well, they have their work cut out for them trying to make all of the pieces of the puzzle fit together by the end of the year. Typically, it is estimated that about 5,000 fire apparatus units are produced in this country a year. Somebody is going to have to pay for all of that redesigning, and that, of course, will be YOU!

In addition to the possible redesign of the cab, the aftermarket accessories such as larger radiators, fans, and the muffler/filter will also add to the cost of the rig. All of the engine/chassis combinations will have to be tested and certified to meet the engine manufacturers’ installation requirements.

The engine manufacturers have not yet released their compliant engines, so no one knows exactly what effect these new regulations will have on their price. It certainly won’t be going down anytime in the near future; that’s for sure! Taking into consideration the requirements for new electronic monitoring equipment and the design costs involved, the compliant engines will significantly increase the cost of your next apparatus. At least the engine manufacturers can recoup their design change costs over the whole trucking industry, not just the fire departments as the apparatus manufacturers must do.

Finally, fuel and maintenance costs most likely will rise. Although low-sulfur fuel is available in some locations, an EPA document I reviewed for this article indicated that the EPA is “providing additional hardship provisions for small refiners to minimize their economic burden in complying with the 15-ppm sulfur standard and giving addition flexibility to refiners subject to a Geographic Phase-in Area.” This certainly leads me to believe that there is an economic cost involved is reducing the sulfur content, and it will be passed on to the consumer.

As the diesel engine and its many components become more complicated, additional training and diagnostic equipment for the local “fire shops” will be necessary. The same will hold true for commercial repair facilities that maintain some of our fleets.


Although there is some disagreement among the manufacturers, it is understood that pre-2007 engines that have been purchased by the apparatus manufacturers and installed in the chasses can still be delivered beyond 2007. In other words, if you have an aerial truck in production and it’s not scheduled for delivery until January 2007, you’re still okay. Information received indicates that the engine manufacturers are not interested in, and are sensitive to, “stockpiling” the older engines to avoid compliance. I believe that the engines that are committed to each manufacturer most likely will be exhausted before the year’s end and the new designs will be in full production by the start of 2007.

As purchasers realize the price increase, configuration, and operational changes that accompany the 2007 regulations, I can foresee a larger than usual demand for apparatus earlier this year.


Although the fire service is only a small part of the pollution problem, the EPA is taking these steps, which they predict will result in substantial benefits to the public health and welfare, by reducing diesel emissions.

As a result of this program, each new truck and bus will operate more than 90 percent cleaner than the 2002 models. The clean-air impact of this program will be dramatic when fully implemented. These emission reductions are estimated to prevent 8,300 premature deaths, more than 9,500 hospitalizations, and 1.5 million workdays lost. That has to be good for all of us!

Author’s note: Thanks to American LaFrance, Inc.; Fire Research Corporation; E-One; and Pierce Manufacturing for providing the background material and information used in this article.

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