As we have noted previously, EPA has had difficulty in promulgating a revised National Ambient Air Quality Standard for ozone. Whenever the revised NAAQS is issued – and EPA is under court deadline to propose a draft by December 1, 2014 and a issue a final by October 1, 2015 – the actual standard that EPA is likely to issue is coming into focus.
Late last week, EPA’s Clean Air Science Advisory Committee released a draft letter to EPA providing its comments on review of EPA’s draft Policy Assessment of the ozone NAAQS. The contents of the letter are not a surprise, and they provide more justification for EPA to lower the NAAQS. Assuming that the full CASAC supports the draft – and I’d be shocked if it does not – EPA will have little discretion not to lower the NAAQS.
As readers know, the current ozone NAAQS is 75 ppb and EPA has been considering a range for a revised NAAQS of 60 ppb to 70 ppb. The CASAC panel’s take?
The CASAC concurs that 60 ppb is an appropriate and justifiable scientifically based lower bound for a revised primary standard. This is based upon findings of adverse effects, including clinically significant lung function decrements and airway inflammation, after exposures to 60 ppb ozone in healthy adults with moderate exertion, with limited evidence of adverse effects below 60 ppb.
That last sentence has to terrify those opposing the more stringent NAAQS.
The panel letter specifically states that it is still deliberating regarding its advice for an upper bound on the NAAQS. However, the draft letter summarizes the evidence, stating that:
At a level of 70 ppb for the averaging time and form of the current standard, clinical and epidemiological studies show adverse effects to human health.
That too, should be worrisome to opponents of the more stringent NAAQS. It’s hard for me to see that EPA would set a NAAQS at a level where clinical and epidemiological studies show adverse effects. Given the important role that the courts have given to CASAC’s views in determining whether EPA has exercised its discretion reasonably, I’d expect environmental NGOs to challenge a NAAQS set as high as 70 ppb – and there is a good possibility that they would prevail.
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