Feb. 3 — Scientific evidence supports setting a more
stringent ozone air quality standard, the Environmental Protection Agency said
in a draft document Feb. 3.
The EPA is in the process of deciding
whether to revise the current ozone national ambient air quality standard of
75 parts per billion, and a newly released draft policy assessment said the EPA would be justified
in setting a standard between 60 ppb and 70 ppb.
“Compared to the
current standard, a revised standard with a level from 70 to 60 ppb would be
expected to increase public health protection against both short- and long-term
[ozone] exposures, including for members of at-risk populations,” the EPA
document, which was prepared by the agency's staff, said.
ozone standard would lead to new requirements for emissions controls on sources
that emit nitrogen oxides and volatile organic compounds, which contribute to
ozone formation, including industrial facilities, power plants and vehicles.
The Clean Air Act requires the EPA to review
and consider revising air quality standards every five years. The EPA revised
the ozone standard most recently in 2008 and missed its five-year deadline of
2013 to revise them. Advocacy groups are suing the EPA for missing the deadline
and have asked a federal district court to order the agency to propose the rule
by December 2014 and finalize it by October 2015.
A policy assessment
analyzes scientific and technical information about ozone exposure and draws
conclusions about policy implications. The EPA released the first draft of the
policy assessment in 2012, and the newly released version is the second
The policy assessment is a key document in the EPA's review
process. The Clean Air Scientific Advisory Committee will discuss the
assessment at a meeting March 25 to 27, and the EPA expects to finalize the
policy assessment this summer.
An ozone standard between of 60 ppb and
70 ppb has been discussed for years. Before the EPA set the 75 ppb standard in
2008, the scientific advisory committee recommended a more stringent standard
in the 60 ppb to 70 ppb range.
When President Barack Obama took office,
the EPA announced it would reconsider the 75 ppb standard and issued a
proposed rule with a standard between 60 ppb and 70 ppb. Obama eventually
stopped that rulemaking process, and it later was disclosed that former EPA
Administrator Lisa Jackson was prepared to finalize the standard at 70 ppb.
The latest draft said that although
such a range could be justified, the final decision on the standard is up to
EPA Administrator Gina McCarthy.
“In drawing these preliminary
conclusions, staff additionally notes that the final decision on the adequacy
of the current standard and consideration of potential alternative standards is
largely a public welfare policy judgment to be made by the Administrator,
drawing upon the scientific information as well as judgments about how to
consider the range and magnitude of uncertainties that are inherent in the
scientific evidence and technical analyses,” the assessment said.
Feb. 3, the EPA released the second drafts of documents called risk and exposure assessments, which evaluate the effects
of ozone exposure. It said the agency has “estimated that exposures and risks
remain after just meeting the existing standards and that in many cases, just
meeting alternative standard levels results in reductions in those exposures
To contact the reporter on this story: Jessica Coomes in Washington at
To contact the editor responsible for this story: Larry
Pearl at email@example.com
The second draft policy assessment,
released Feb. 3, is available at http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_2008_pa.html.
The second draft risk and exposure assessments, also released Feb. 3, are
available at http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_2008_rea.html.
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