Regulatory Announcement

EPA Grants Relief for Fire Trucks 

and Ambulances; Proposes SCR 

Maintenance and Short-Term Relief 

for Nonroad Equipment 

With the relief announced by the Administration today, emergency 

vehicles such as ambulances and fire trucks would no longer 

face power disruptions related to their diesel emission control systems.

In a proposal mirrored in a direct final action, the U.S. Environmental 

Protection Agency (EPA) is offering regulatory flexibility for dedicated 

emergency vehicles and their engines, related to implementation of 

EPA’s 2007/2010 criteria pollutant standards. This fact sheet contains an 

overview of the emergency vehicle flexibility as well as the other elements 

of EPA’s proposed action: SCR maintenance provisions and regulatory 

flexibility for nonroad equipment used during emergency responses. 

Emergency Vehicle Flexibility 

Why is EPA Taking This Action? 

Typically, the engines powering our nation’s emergency vehicles belong to the same 

regulated engine families as engines that are installed in similarly sized vehicles sold 

for other public and private uses. Since MY 2007, EPA’s emission standards for diesel 

engines have spurred wider use of some after-treatment technology that requires 

routine maintenance for sustained engine performance. The emission control systems 

built for diesel engines are robust and effective for the majority of the heavy-duty 

fleet; however, when this maintenance does not occur as designed, many engines 

are set to cut power to prevent abnormal conditions from causing damage or excess 

emissions. In this action, EPA is offering engine manufacturers the flexibility to avoid 

such abnormal conditions and ensure that there will not be emission-related power 

Office of Transportation and Air Quality 

EPA-420-F-12-025 

May 2012 
Regulatory Announcement

 

 

loss on emergency vehicles. In doing so, EPA is helping manufacturers to address a potentially 

serious public safety issue. 

What Revisions is EPA Proposing? 

EPA is proposing revisions that would allow manufacturers to request and EPA to approve 

modifications to emissions control systems on new and in-use emergency vehicles so they can be 

operated as intended, without reduced performance during emergency situations. For new engine 

or vehicle certifications, these improved controls or settings would generally be approved as 

auxiliary emission control devices (AECD’s). For in-use engines and vehicles, EPA is proposing 

to allow engine and vehicle manufacturers to submit requests for EPA approval of Emergency 

Vehicle Field Modifications. 

Direct Final Rule 

While EPA is accepting comment on all parts of the rule, EPA is also publishing the provisions 

for dedicated emergency vehicles in a Direct Final Rule. This means that separable emergency 

vehicle provisions that do not receive adverse comment will become final 60 days from publication in the Federal Register. EPA will withdraw the parts of the direct final rule that receive 

adverse comments, and respond to all comments as part of a final rule. 

Scope of the Rule 

This flexibility is being offered for dedicated emergency vehicles, which for the purposes of this 

action are fire trucks and ambulances with engines subject to EPA’s heavy-duty diesel standards. 

EPA is also offering this flexibility for emergency equipment meaning specialized vehicles for 

use in fighting aircraft and wildland fires. The flexibility offered in this rule is only available to 

manufacturers of vehicles and equipment meeting these definitions. The intent is to cover 

vehicles with demands of duty where it would present unacceptable risks to public health or 

safety for the driver to lose control of the vehicle due to conditions of the emission control 

system. 

SCR Maintenance 

Why is EPA Taking This Action? 

Selective Catalytic Reduction (SCR) is now a common technology in the transportation sector. 

This technology requires use of a diesel exhaust fluid that reacts in the system, is consumed, and 

must be refilled for the nitrogen oxides (NOx) reductions to be sustained. When the 2007/2010 

standards were adopted, no refill intervals were specified for this fluid used with SCR systems. 

The need to refill this fluid wasn’t even listed as being required, because SCR was not predicted 

to be this successful of a technology. EPA has determined that it is reasonable to add fluid 

replenishment to the list of scheduled emission-related maintenance in the regulations, rather 

than rely on a case-by-case approval as has been done up to now. This action would improve the 

clarity and transparency of EPA’s requirements for maintaining emission control systems. 

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Regulatory Announcement

 

 

What Revisions is EPA Proposing? 

EPA is proposing to set a fluid refill interval equal to the scheduled oil change interval for 

light-duty vehicles and light-duty trucks that use SCR.1 EPA is accepting comment on this in 

relation to engines that use advanced synthetic oils with extended oil change intervals. EPA is 

proposing to set a fluid refill interval at least as far (in miles or hours) as the vehicle’s fuel capacity 

for centrally-fueled heavy-duty vocational vehicles such as dump trucks, concrete mixers, and 

refuse trucks. For all other vehicles that use SCR, the fluid refill interval must provide a range of 

vehicle operation that is no less than twice the range of vehicle’s fuel capacity. Finally, for SCRequipped nonroad diesel engines, EPA is proposing a fluid refill interval at least as far (in miles 

or hours) as the vehicle’s fuel capacity. 

Nonroad Engines in Temporary Emergency Situations 

Why is EPA Taking This Action? 

Diesel engines in most modern nonroad equipment are subject to EPA’s technology-forcing 

standards, phasing in through 2015. As noted above, when routine emission-control maintenance 

does not occur as designed, many engines are set to cut power to prevent abnormal conditions 

from causing damage or excess emissions. Today’s proposed action regarding nonroad equipment 

would allow short-term relief from emissions standards only when such equipment is needed to 

respond to an emergency such as a flood or hurricane, so that any pre-set emissions or engine 

protection measures do not prevent the equipment from performing life-saving work. 

What Revisions is EPA Proposing? 

EPA is proposing revisions that would allow manufacturers to request and EPA to approve 

AECDs as part of the engine certification process. This flexibility is intended primarily for new 

engines used for power generation or in construction equipment, though if justified EPA may 

grant approval for other engines and/or equipment in use. Manufacturers would be responsible 

for activation of any such AECD as well as reports that document such activation was related to 

a verifiable emergency. 

What are the Economic, Health and Environmental Impacts? 

EPA expects the economic effects of this proposal to be small, and to potentially have benefits 

that are a natural result of easing constraints. No new regulatory burdens would be imposed. For 

SCR maintenance, EPA is providing regulatory certainty that will allow affected manufacturers 

to plan their future product development. For emergency vehicles, the societal costs of inaction 

would appear to be much greater than the potential costs of this action. 

We expect any environmental impacts from today’s action would be small. Due to the optional 

and voluntary nature of the flexibilities offered, the emissions impacts will depend on which 

options and strategies are employed, how many vehicles are modified, and how often the 

AECD’s are turned on. There are no anticipated adverse environmental impacts from the 

SCR maintenance proposal. 

1

 Such as a half-ton diesel pickup truck or a diesel SUV 

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Regulatory Announcement

For More Information 

You can access the direct final rule, the proposed rule and related documents on EPA’s Office of 

Transportation and Air Quality (OTAQ) Web site at: 

www.epa.gov/otaq/highway-diesel/regs.htm. 

For more information on these and related rules, please contact EPA through EPA OTAQ 

Public Inquiries at: 

www.epa.gov/otaq/oms-cmt.htm 

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