Proposal to Revise the Primary National Ambient Air Quality by T4zZpUK


									Revised National Ambient Air
      Quality Standard
  for Sulfur Dioxide (SO2)

         Ian D. Cohen
         EPA Region 1
         617 918-1655

        August 5, 2010

• On June 2, 2010 EPA Administrator Lisa Jackson signed
  a final rule which will strengthen the primary National
  Ambient Air Quality Standards (NAAQS) for sulfur
  dioxide (SO2) to improve public health protection
• EPA’s rule is consistent with the recommendations of the
  Clean Air Scientific Advisory Committee
• This rule does not cover the secondary SO2 standard.
• The final rule was published on June 22, 2010

   – For more information, go to
      SO2-Related Health Effects
• Exposure to SO2 is associated with an array of
  adverse respiratory effects, including:
  – Narrowing of the airways leading to difficulty breathing
  – Increased asthma symptoms, especially during exercise
  – Increased Emergency-department visits and hospital admissions
    for respiratory illnesses

• Children, the elderly and asthmatics are among
  the most at-risk populations
               Nationwide Sources
                of SO2 Pollution
• Fossil fuel combustion at
power plants (66%) and
other industrial facilities
(29%) are the main sources
of SO2 emissions

• Other sources include
industrial processes such as
extracting metal from ore,
and the burning of high sulfur
fuels by locomotives, large
ships, and non-road
 Previous Primary SO2 Standards

• 24-hr standard: 140 parts per billion (ppb)
• Annual average standard: 30 ppb
• Last Reviewed in 1996
               New Health Evidence
• New scientific studies provide stronger evidence of links between
  short-term SO2 exposures, ranging from 5 minutes to 24 hours, and
  adverse respiratory outcomes

• Controlled human exposure studies of exercising asthmatics indicate
  that 5-10 minute exposures are clearly associated with respiratory
  responses judged to be adverse

• Epidemiologic studies show an association between short-term SO2
  exposure and increased visits to emergency departments and hospital
  admissions for respiratory illnesses, particularly in at-risk populations
  including children, the elderly, and asthmatics
    – Over 50 U.S. and international studies since last review
    – Most conducted in locations with SO2 concentrations below current
      standards, including a few large multi-city studies
    – Studies show effects generally occurring independently of the presence of
      co-pollutants, including particulate matter
               New SO2 Standard
• EPA is replacing the annual and 24-hour SO2 primary
  standards with a new 1-hour SO2 standard set at 75
  parts per billion. In general, EPA will revoke the 24-hour
  and annual standards for areas that meet the 1-hour

   – The 24-hour and annual SO2 standards will be retained until one
     year after an area is designated attainment for the 1-hour
     standard unless required by a SIP or other plan.
   – Areas designated nonattainment for the 1-hour standard will also
     retain the 24-hour and annual standards
   – The Standard is based on the 3-year average of either the 99th
     percentile concentration or the 4th highest daily maximum
     concentration in a year
   Current Monitored and Projected
Concentrations of SO2 in Massachusetts
 County      2006 – 2008 Conc.     Proj. 2020 Design Value
            (average 1-Hour 99th    (average 1-Hour 99th
                 percentile)              percentile)
 Bristol            58                       18

Hampden             30                       31

Hampshire           14                       13

 Suffolk            28                       25

Worcester           17                       19
                Emissions (Tons)



19 0
19 1
19 2
19 3
19 4
19 5
19 6
19 7
19 8
20 9
20 0
20 1
20 2
20 3
                                                                    in EPA’s Acid Rain Program

20 4
20 5
20 6
20 7
                                                            SO2 Emissions from Massachusetts Facilities
        SO2 Monitoring Network
• In the final rule, EPA is requiring fewer monitors than proposed,
  because the Agency plans to use a hybrid approach combining air
  quality modeling and monitoring to determine compliance with the
  new SO2 health standard.

• EPA is setting specific minimum requirements that inform states on
  where they are required to place SO2 monitors. Approximately 163
  SO2 monitoring sites nationwide are required by this rulemaking.
  There are 9 required monitoring sites in Region 1.

• The final monitoring regulations require monitors to be placed in
  Core Based Statistical Areas (CBSAs) based on a population
  weighted emissions index for the area. The final rule requires:
    – 3 monitors in CBSAs with index values of 1,000,000 or more;
    – 2 monitors in CBSAs with index values less than 1,000,000 but greater
      than 100,000; and
    – 1 monitor in CBSAs with index values greater than 5,000.
Monitors Required in New England

•   Barnstable Town, MA (1 monitor)
•   Boston-Cambridge-Quincy, MA-NH (2 monitors)
•   Bridgeport-Stamford-Norwalk, CT (1 monitor)
•   Concord, NH (1 monitor)
•   Hartford-West Hartford-East Hartford, CT (1 monitor)
•   New Haven-Milford, CT (1 monitor)
•   Providence-New Bedford-Fall River, RI-MA (1 monitor)
•   Springfield, MA (1 monitor)
•   Worcester, MA (1 monitor)
   Use of Dispersion Modeling
• For a short-term 1-hour SO2 standard, it is
  more technically appropriate, efficient, and
  effective to use modeling as the principal
  means of assessing compliance for
  medium to larger sources, and to rely
  more on monitoring for groups of smaller
  sources and sources not as conducive to
  modeling. Such an approach is consistent
  with EPA’s historical approach and
  longstanding guidance for SO2.
     Hybrid Monitoring/Modeling
   Approach to Assess Compliance
• For sources or groups of sources that have the potential to cause or
  contribute to a violation of the standard, EPA anticipates using
  refined source-oriented dispersion modeling to:
    – identify violations, and
    – determine compliance.
• EPA plans to develop modeling and implementation guidance for
  the states addressing a variety of issues including how to:
    – Appropriately compare the model results to the new SO2 standard, and
    – Identify and appropriately assess the air quality impacts of smaller SO2
      sources that may potentially cause or contribute to a violation of the new
      SO2 standard.
• EPA intends to issue guidance on conducting air dispersion
  modeling to help determine compliance with the new standard.
• EPA will provide an opportunity for public comment on this guidance
      Implementation Schedule
        Milestone             Date
Proposal Published       December 8, 2009

Final Rule Signed          June 2, 2010

Final Rule Published      June 22, 2010

State Designation          June 2, 2011
Recommendations to EPA
Final Designations         June 2, 2012

SIPs Due                  February 2014

Attainment Date            August 2017

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