In a draft document released today, U.S. EPA staff say that based on available scientific evidence, the agency should consider tightening its current ozone standard to a level as low as 60 parts per billion.
A draft policy assessment meant to distill the available scientific and technical information says that the agency should lower its National Ambient Air Quality Standard (NAAQS) for ground-level ozone, currently set at 75 ppb. That standard, the document says, may not be adequate to protect the public from the harmful effects of smog.
A standard between 70 ppb and 60 ppb "could provide an appropriate degree of public health protection and would result in important improvements in protecting the health of at-risk populations and lifestages."
That recommendation is the range EPA had previously considered in President Obama's first term before the White House put a hold on the revisions in 2011. The NAAQS was last revised to 75 ppb in 2008, and environmental groups have sued the agency seeking firm deadlines for a new standard, which is scheduled to be updated every five years.
In a separate health and risk exposure assessment, agency staff says that setting a standard in the 60-70 ppb range would result in reduced child exposure, lower hospitalization and mortality rates, and reduced risk of lower lung function.
The documents are meant to inform agency scientists and policymakers ahead of a meeting of the Clean Air Scientific Advisory Committee at the end of March. Following that meeting, the agency is expected to release a proposal, although the administration has not specified a timeline.
Ozone, a major component of smog, is linked to a host of health problems, including asthma and respiratory ailments and diseases, and EPA has said it is linked to climate change.
Environment and public health groups have pushed EPA to lower the NAAQS to 60 ppb, saying that's where the agency could maximize the public health benefits and that such a standard would be achievable. Industry groups have cautioned that 60 ppb would be too low and would leave cities and states at risk of being out of attainment with the federal standard.
Click here to read the draft policy assessment.
Click here to read the draft health and risk exposure assessment.