Regulatory

Announcement

Office of Transportation

and Air Quality

EPA420-F-06-021

February 2006

Control of Hazardous Air

Pollutants from Mobile Sources

The U.S. Environmental Protection Agency (EPA) is issuing a 

proposed rule to reduce hazardous air pollutants from mobile sources. 

Hazardous air pollutants, also known as air toxics, include benzene 

and other hydrocarbons such as 1,3-butadiene, formaldehyde, 

acetaldehyde, acrolein, and naphthalene. Air toxics emitted by motor 

vehicles and other moving sources (called “mobile source air toxics,” 

or MSATs) contribute significantly to the nationwide risk from breathing 

outdoor air toxics. The proposed standards would significantly lower 

emissions of benzene and the other air toxics in three ways: (1) 

by lowering benzene content in gasoline; (2) by reducing exhaust 

emissions from passenger vehicles operated at cold temperatures 

(under 75 degrees F); and (3) by reducing emissions that evaporate 

from, and permeate through, portable gasoline containers (gas cans). 

Background

Section 202(l) of the Clean Air Act requires EPA to set standards to control hazardous air pollutants from motor vehicles, motor vehicle fuels, 

or both. EPA published a final rule under this authority in March 2001 

that established toxics emissions performance standards for gasoline 

refiners and committed to additional rulemaking to evaluate the need for 

and feasibility of additional controls. This proposal fulfills that commitment from the 2001 rule.

In addition, EPA is proposing emission standards for gas cans under the 

consumer products authority of the Clean Air Act (section 183(e)).
Reason to Reduce Mobile Source Air Toxics 

MSATs are known or suspected to cause cancer or other serious health 

or environmental effects. Benzene is of particular concern because it is 

a known carcinogen and most of the nation’s benzene emissions come 

from mobile sources. People who live or work near major roads, or 

spend a large amount of time in vehicles, are likely to have higher exposures and higher risks. People living in homes with attached garages are 

also likely to be exposed to benzene levels that are higher than average.

Many MSATs are part of a larger category of mobile source emissions 

known as volatile organic compounds (VOC), which contribute to the 

formation of ozone and possibly particulate matter (PM). Ozone and PM 

can contribute to serious public health problems, including premature 

mortality, aggravation of respiratory and cardiovascular diseases, damage 

to lung tissues and structures, altered respiratory defense mechanisms, 

and chronic bronchitis.

Fuel Program

EPA is proposing that, beginning in 2011, refiners would meet an annual 

average gasoline benzene content standard of 0.62 percent by volume 

on all their gasoline, both reformulated and conventional, nationwide. 

The national benzene content of gasoline today is about 0.97 percent. 

(Gasoline sold in California would not be covered because California has 

already implemented more stringent standards similar to those EPA is 

proposing.) 

EPA is proposing a nationwide averaging, banking, and trading program 

as part of the average standard. The Agency is expecting gasoline in all 

areas of the country would have lower benzene levels than they do now, 

and there would be less geographic variability in gasoline benzene levels. 

EPA is proposing special compliance flexibility for approved small refiners or any refiner facing extreme unforeseen circumstances.

Vehicle Program

EPA is proposing new standards to reduce non-methane hydrocarbon 

(NMHC) exhaust emissions from new gasoline-fueled passenger vehicles. NMHCs include many mobile source air toxics, such as benzene. 

Recent research indicates that the current test procedures often do not 

result in robust control of NMHCs at colder temperatures below 75 degrees. Therefore, we are proposing a cold temperature test where passen-
ger vehicles would be subject to an NMHC exhaust emissions standard. 

As shown in Table 1, each manufacturer’s vehicles would be subject to 

a sales-weighted fleet average NMHC level of 0.3 grams/mile for lighter 

vehicles weighing 6,000 pounds (lbs) or less. Vehicles above 6,000 

lbs (which include trucks up to 8,500 lbs and passenger vehicles up to 

10,000 lbs) would be subject to a sales-weighted fleet average NMHC 

level of 0.5 grams/mile. The standard would phase in between 2010 and 

2013 for the lighter vehicles, and between 2012 and 2015 for the heavier 

vehicles. A credit program and other provisions would provide flexibility to manufacturers, especially during the phase-in periods. 

Table 1 – Proposed Cold Temperature NMHC Standard and Phase-In 

Schedule

Vehicle Weight Class 

(GVWR)A

NMHC Emission 

Level (grams/mile)

Phase-In ScheduleB (percent)

2010 2011 2012 2013 2014 2015

6000 lbs or less 0.3 25 50 75 100

6001 to 8500 lbs, plus 

passenger vehicles up 

to 10,000 lbs

0.5 25 50 75 100

A Gross Vehicle Weight Rating

B Percent of each manufacturer’s fleet, by model year, that must comply with the standard.

Along with the vehicle exhaust standards, we are also proposing more 

stringent evaporative emission standards for new passenger vehicles. 

The proposed standards are equivalent to California’s standards and 

would codify the approach that manufacturers are already taking for 50-

state evaporative systems. We are proposing to implement the evaporative emission standards in 2009 for lighter vehicles and in 2010 for the 

heavier vehicles. 

Gas Can Program

EPA is proposing standards that would limit hydrocarbon emissions 

that evaporate from or permeate through gas cans. Gas cans (portable 

gasoline containers) are consumer products used to refuel a wide variety 

of gasoline-powered equipment, including lawn and garden equipment, 

recreational equipment, and passenger vehicles that have run out of 

gas. Starting with containers manufactured in 2009, the standard would 

limit evaporation and permeation emissions from these containers to 

0.3 grams of hydrocarbons per gallon per day. We are also proposing 

test procedures and a certification and compliance program in order to 

ensure that gas cans would meet the emission standard over a range of 

in-use conditions. 
EPA has worked closely with major gas can manufacturers and it is expected that the new cans will be built with a simple and inexpensive inner coating and other minor modifications to comply with the proposed 

standards.

Program Benefits

The proposed fuel benzene standard and hydrocarbon standards for 

vehicles and gas cans would together reduce total emissions of mobile 

source air toxics by 350,000 tons in 2030, including 65,000 tons of 

benzene. As a result of this proposal, in 2030, passenger vehicles would 

emit 45 percent less benzene, gas cans would emit 78 percent less benzene, and the gasoline would have 37 percent less benzene overall. 

In addition, the hydrocarbon reductions from the vehicle and gas can 

standards would reduce volatile organic compound (VOC) emissions 

(which are precursors to ozone and can be precursors to PM2.5) by over 

1 million tons in 2030. The proposed vehicle standards would reduce 

direct PM2.5 emissions by 20,000 tons in 2030 and may also reduce 

secondary formation of PM2.5. Once the regulation is fully implemented, 

these PM reductions will result in 1,000 premature deaths avoided annually. 

We estimate that most of the benefits of this proposal would come from 

the reduced direct PM2.5 emissions from the vehicle standards, estimated 

to be about $6 billion in 2030. Some additional benefits would come 

from reductions in mobile source air toxics and VOCs, although we have 

not been able to monetize these benefits. 

Estimated Costs per Program

The additional cost of producing gasoline to comply with the new benzene standard is expected to average $0.0013 per gallon. This per-gallon 

cost would result from an industry-wide investment in capital equipment 

of $500 million to reduce gasoline benzene levels, or an average of $5 

million in capital investment in each refinery that adds such equipment. 

We estimate that the annual net social costs of this proposal would be 

about $200 million in 2030 (expressed in 2003 dollars). These net social 

costs include the value of fuel savings from the proposed gas can standards, which would be worth $82 million in 2030.
We estimate that the additional cost to manufacturers would be less than 

$1 per vehicle. The costs would be associated with vehicle research and 

development and recalibration, as well as facilities upgrades to handle 

additional development testing under cold conditions. We are not anticipating additional costs for the proposed vehicle evaporative emissions 

standard since manufacturers will likely continue to produce 50-state 

evaporative systems that meet California’s standards. 

The average additional cost of producing gas cans that comply with the 

new standards would be less than $2 per can. The reduced evaporation 

from gas cans would result in fuel savings over the life of the can that 

would more than offset the increased cost for the gas can. 

Public Participation Opportunities

We welcome your comments on this proposed rule. For instructions on 

submitting written comments, please see the Federal Register notice, 

which is available from the EPA Air Docket by calling 202-566-1742; 

please refer to Docket No. EPA-HQ-OAR-2005-0036. In addition, you 

can access the proposed rule and related documents on EPA’s Office of 

Transportation and Air Quality (OTAQ) Web site at: http://www.epa.

gov/otaq/toxics.htm

For More Information

For more information on this proposed rule, please contact Kathryn 

Sargeant, Director, Health Effects, Benefits, and Toxics Center, at:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality

2000 Traverwood Drive

Ann Arbor, MI 48105

(734) 214-4441

E-mail: sargeant.kathryn@epa.gov