Air Toxics:
Current Status, New Directions
Kenneth L. Mitchell, Ph.D.; Chief
Air Toxics Assessment & Implementation
U.S. Environmental Protection Agency
Atlanta, Georgia
Good Afternoon!
• What are Air Toxics?
• Program Overview
• Current Status
• Future Directions
What do we mean by “Air Toxics?”
Six“Criteria”
Pollutants
O3, NO2, SO2, Pb
CO, PM
Mobile Source
Pollutants
The Federal
Clean Air Act
21 Chemicals &
Mixtures
Hazardous
Air Pollutants
(Air Toxics)
187 Chemicals &
Compounds
Why are air toxics a problem?
Millions of Sources
Cancer
Many are Highly
Toxic
Kidney,
Liver
Damage
Asthma,
Chronic
Bronchitis
Skin Rashes
Birth Defects,
Miscarriages
Developmental
Problems in
Children
Cough,
Throat
Irritation
Nervous
System
Damage
Sources/Populations
Colocated
Some Persist &
Bioaccumulate
WIND DIRECTION
A
B
TRANSFORMATION
WET DEPOSITION
DISPERSION
DRY DEPOSITION
EVAPORATION/
REENTRAINMENT
IN AIR
BIOACCUMULATION
IN FOOD
CANCER
TARGET
ORGAN/TISSUE
INGESTION
OTHER NON-CANCER
ENDPOINTS
EXCRETION
INTAKE/UPTAKE
DERMAL
INHALATION
There Are Sources Everywhere!
Courtesy of Sustaining the Environment and Resources for Canadians
Types of Sources
Major Sources
Area Sources
10 TPY or more of one HAP
Or
25 TPY or more of a
combination of HAPS
Less than 10 TPY of one HAP
Or
Less than 25 TPY of a
combination of HAPS
Types of Sources
Outdoor Air
Indoor Sources
Mobile Sources
Not regulated but pose
(on average) 3-5 times
the concentrations of
outdoor air
On- and Off-road;
Engines, fuels, and operation
all contribute to pollution;
21 MSATs
THE NATIONAL AIR TOXICS PROGRAM
(Stationary, Mobile, and Indoor Air Sources)
Regulatory
Approaches
Risk Assessment
Methods for
Facility Specific &
Community-Scale
Risk Decision
Criteria for
Facilities and
Communities
Voluntary
Reduction
Options
Education
and
Outreach
Achieve Meaningful Reductions
At The Local Level
SLT
Program
Structure
Design
Residual Risk – Mandate from Congress
• Assess risks from stationary
sources that emit air toxics
after technology-based
(MACT) standards are in place
• Set additional standards if
MACT does not protect public
health with an “ample margin
of safety”
• Set additional standards if
necessary to prevent adverse
environmental effects
Residual Risk – Status
• Coke ovens – April 2005
• March 2006
–
–
–
–
Industrial cooling towers
Magnetic tape
Ethylene oxide sterilizers
Gasoline distribution
• Dry cleaning – July 2006
• HON – December 2006
• Halogenated Solvents – December 2006
Residual Risk – New Directions
• Develop “total facility
low-risk demonstration
(TFLRD)” rule
• Develop comprehensive
or generic residual risk
rule (GRRR)
Area Sources – Current Status
• The Integrated Urban Strategy was
published July 19, 1999
– Identified chemicals of concern
– Identified initial list of area source categories
• 70 source categories have been listed
– Listing completed in November 2002
– Source categories required to be “subject to
regulation”
– 16 rules completed
20 of the 70 Standards
– 4 under court order
Area Sources –
Recent Additional Court Ordered Schedule
• Dec. 15, 2006
4 categories
• June 15, 2007
6 categories
• Dec. 15 2007*
10 categories
• June 15, 2008
10 categories
• Dec. 15, 2008
10 categories
• June 15, 2009
10 categories
50 Categories
*3 area source standards subject to CAA 112(c)(6) (related
to PBT chemicals) must be promulgated by this date.
Area Sources – Future Directions
• National Rulemaking Approach
– Establish national standards for
source categories that have a national
level of concern
• Flexible Rulemaking Approach
– Enact a rule, covering a set of
categories, that will regulate how
categories are controlled at the local
level based on local needs
– EPA will provide guidance on control
approaches
Mobile Source Air Toxics (MSATs) –
Current Status
• In March 2001, EPA published first MSAT
rule
• Toxics emissions performance standard
for gasoline
– Refinery-specific baselines to ensure no
backsliding from 1998-2000 performance
• No additional standards for fuels or
vehicles
• Identified data gaps and committed to
additional research
• Committed to additional rulemaking to
evaluate the need for and feasibility of
additional controls
Mobile Source Air Toxics –
Future Directions
• Proposed Rule signed on
February 28, 2006
• Public hearing on April 12
• 60-day comment period
(through May 30th)
• Final rule by February 9, 2007
Mobile Source Air Toxics –
Future Directions
• Benzene content standard
for gasoline
• Vehicle standards
– Exhaust emissions
– Evaporative emissions
• Gas can standards
Diesel Exhaust –
Current and Future Directions
• Building on the successes of EPA’s regulatory and
voluntary efforts to reduce emissions from diesel
engines, EPA has created the National Clean Diesel
Campaign (NCDC)
– Successful implementation of the 2007 Highway Engine Rule and the
Clean Air Nonroad Diesel Rule
– Develop new emissions standards for locomotive and marine diesel
engines
– Promote reduction of emissions for existing diesel engines through costeffective and innovative strategies, including use of cleaner fuels,
retrofitting and repairing existing fleets, idling reduction among others
Thanks for your attention!
Dr. Ken Mitchell
U.S. Environmental Protection Agency
(404) 562-9065
mitchell.ken@epa.gov
http://www.epa.gov/region4/air/airtoxic/index.htm