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Regulatory

Announcement

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-00-025

July 2000

Office of Transportation and Air Quality

Control of Emissions of Hazardous

Air Pollutants from Mobile Sources

Highlights of the Proposed Rule

EPA is proposing a program to address emissions of hazardous air

pollutants from mobile sources. The proposal has four parts:

• For the first time, EPA identifies those compounds that should be

considered Mobile Source Air Toxics (MSATs). This is necessary

because, unlike the provisions governing toxic emissions from

stationary sources, the Clean Air Act does not include a list of

pollutants that should be classified as motor vehicle toxics. The list

of 21 MSATs (which is attached) includes various compounds that

result from fuel combustion in motor vehicle engines, as well as

certain metal compounds and diesel exhaust.

The U.S. Environmental Protection Agency is issuing a proposed rule

to address emissions of toxic air pollutants from mobile sources. In

addition to identifying 21 mobile source air toxics, this rule proposes

limits on the amount of benzene in gasoline. It also sets out a Technical

Analysis Plan whereby EPA will continue to conduct research and

analysis and to revisit in 2003 the need for and feasibility of additional

controls on toxic emissions from motor vehicles and fuels.
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• The proposal includes an evaluation of the effectiveness of federal

emission control programs in reducing emissions of these MSATs.

The analysis shows that existing programs put in place to reduce

motor vehicle emissions of ozone precursors, such as VOCs and

NOx, and particulate matter (PM), as well as programs that will

take effect in the future, will reduce MSATs for the next 20 years.

Existing and future programs that reduce MSATs include reformulated gasoline (RFG) national low emission vehicles (NLEV) the

Tier 2 tailpipe standards for passenger vehicles and gasoline sulfur

control and the recently proposed program to establish new exhaust

standards for diesel-powered large trucks and buses and highway

diesel fuel sulfur control.

• The proposal evaluates whether there are additional measures that

could be put in place at this time to reduce highway MSAT pollutants even more. With regard to fuels-based controls, EPA proposes

to set maximum limits on the amount of benzene that can be added

to RFG and conventional gasoline. The proposed standards would

require refiners to maintain their average 1998-1999 benzene levels.

Benzene is a known human carcinogen that is a common component of gasoline. With regard to vehicle-based controls, the proposal

concludes that the Tier 2 and proposed heavy duty standards are the

most stringent controls feasible at this time to reduce MSAT emissions from motor vehicles.

• The proposal sets up a process by which EPA will continue to

conduct research and analysis and, in 2003, revisit the question of

the need for and feasibility of additional controls on vehicles or

fuels.

Background

In response to public health concerns, Congress instructed EPA as part of

the Clean Air Act Amendments of 1990 to develop a program to address

emissions of toxic air pollutants from motor vehicles and their fuels.

First, EPA was instructed to study the need for and feasibility of controlling toxic emissions associated with motor vehicles and their fuels. EPA

completed this study in 1993 and updated it in 1999. The studies: Motor

Vehicle-Related Air Toxics Study, 1993, and Analysis of the Impacts of

Control Program on Motor Vehicles Toxics Emissions and Exposure in

Urban Areas Nationwide, November 1999, are available at http://

www.epa.gov/otaq/toxics.htm.
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Second, we were instructed to set standards for hazardous air pollutants

from motor vehicles and their fuels, or both. Those standards are to be

set based on available technology, taking existing standards, costs, noise,

energy and safety factors, and lead time into account.

Health and Environmental Benefits

Mobile sources are significant contributors of several key air toxics that

are also considered to be urban hazardous air pollutants. These include

1,3-butadiene, acetaldehyde, acrolein, benzene, and formaldehyde. In

addition, diesel exhaust comes virtually only from mobile sources. The

gasoline benzene standards proposed in this action will ensure that

refiners maintain the current RFG and anti-dumping fuel benzene limits.

While this proposal does not contain new, additional control programs to

reduce emissions of toxic air pollutants from mobile sources, it clarifies

that mobile source MSATs are expected to decline significantly over the

next 20 years, particularly gaseous air toxics and diesel exhaust, due to

existing and proposed mobile source emission control programs, including RFG, NLEV, Tier 2, and the proposed large diesel truck and bus

standards.

Cost to Industry

This proposed rule is expected to impose negligible additional costs on

industry, since the proposed standards require that, beginning 2002,

refiners maintain the average 1998-1999 gasoline benzene levels.

Public Participation Opportunities

EPA desires full public participation in arriving at rulemaking decisions.

The Agency solicits comments from all interested parties. Commenters

are especially encouraged to provide specific suggestions for changes to

any aspect of the proposal that they believe needs to be modified or

improved.

EPA will hold a public hearing in August 2000 and will accept written

comments on the NPRM for 30 days after the public hearing. For more

information on the public hearing or for instructions on submitting

written comments, please see the Federal Register notice. It is available

from the EPA Air and Radiation Docket by calling 202-260-7548; please

refer to Docket No. A-2000-12. In addition, the NPRM and related

documents are available at http://www.epa.gov/otaq/toxics.htm
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For More Information

For further information on this proposed rule, please contact:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality

Air Toxics Team

2000 Traverwood Drive

Ann Arbor, Michigan 48105

(734) 214-4349

A t cetaldehyde* D E iesel Exhaus MTB

A e crolein* E e thylbenzen Naphthalen

A * rsenic compounds* F * ormaldehyde Nickel compounds

B e enzene* n * -Hexan POM (Sum of 7 PAHs)

1 * ,3-Butadiene* L e ead compounds Styren

C * hromium compounds* M e anganese compounds Toulen

D * ioxin/Furans* M e ercury compounds Xylen

Proposed List of Mobile Source Air Toxics (MSATs)

* Also on the list of urban HAPs for the Urban Air Toxics Strategy