EPA is issuing an initial draft of the staff paper on ground-level ozone
as part of a process to gather public, technical and scientific input to
ensure that federal air quality standards reflect the latest air
pollution and health effects research. The draft staff paper, "Review
of the National Ambient Air Quality Standards for Ozone," includes
scientific and technical information about ozone related health and
welfare effects, initial results from a human exposure analysis and
health risk assessment, and discussion of a planned vegetation-related
environmental assessment.

This initial draft staff paper does not provide staff recommendations as
to whether or not to change current standards; it is a preliminary step
in a process required by the Clean Air Act to periodically assess the
National Ambient Air Quality Standards. Development of the staff paper
is the second step in this extensive scientific and technical assessment
process. The first step in that process is the preparation of an Air
Quality Criteria Document. The Criteria Document is a comprehensive
assessment of scientific data about the health and environmental effects
associated with the pollutant under review -- in this case, ozone.
EPA's Office of Research and Development released the Second External
Review Draft of the Ozone Criteria Document in August, 2005.

The Clean Air Act requires EPA to set National Ambient Air Quality
Standards for ozone and five other major pollutants considered harmful
to public health and the environment. The law also requires EPA to
periodically review the standards to ensure that they provide adequate
health and environmental protection, and to update those standards as
necessary. EPA last updated the ozone standards in 1997.

The Clean Air Science Advisory Committee (CASAC), a
Congressionally-mandated group of independent scientific and technical
experts, will review the second external review draft Criteria Document
and will provide a consultation on this initial draft of the Staff Paper
at a meeting in Durham, North Carolina on Dec. 6-8, 2005. This meeting
is open to the public. EPA will carefully review and consider comments
received during both the public comment period and the December CASAC
meeting and anticipates release of a final Criteria Document in February
2006. EPA will revise the draft Staff Paper, taking into account CASAC
and public comments, and anticipates release of the next draft in spring
2006.

The preliminary draft Staff Paper is available online at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_sp.html
A fact sheet summarizing the first draft Staff Paper is available at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_plain.html