These commenters variously famous their agreement with the rationale provided by the EPA within the proposal or cited to CASAC comments, together with for a downward adjustment of its recommended values if a three-year average W126 was used quite than skull couple from our last breath all over print face mask a single year index. Some different commenters, together with two teams of environmental organizations, submitted feedback recommending a concentrate on a W126 index level as little as 7 ppm-hrs based mostly on reasons
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than intermittent occurrences of such exposures because of the potential for compounding effects on tree growth. The Administrator additionally notes the proof, as thought-about within the PA and summarized within the proposal, for some perennial species of some results related to a single year’s exposure of a crucial magnitude which will have the potential for some “carry over” of effects on plant growth or replica in the subsequent season. Further, the Administrator notes the prevalence of visible foliar injury and development or yield loss in annual crops or crops associated with exposures of a crucial magnitude. While the Administrator skull couple from our last breath all over print face mask appreciates that the scientific proof documents the consequences on vegetation ensuing from individual growing season exposures of particular magnitude, including these that can have an effect on the vegetation in subsequent years, she can be aware, both of the strengths and limitations of the evidence, and of the information on which to base her judgments with regard to adversity of effects on the general public welfare. The Administrator additionally recognizes uncertainties related to interpretation of the general public welfare significance of results resulting from a single-yr publicity, and that the general public welfare significance of effects related to multiple years of critical exposures are doubtlessly larger than those related to a single year of such exposure. With regard to the highest three-yr common W126 publicity index values that might reasonably be anticipated sooner or later in areas the place a revised commonplace with a fourth-high form is met, we disagree with the commenters as to the importance of the W126 index worth of 19.1 ppm-hrs within the 13-year dataset. This value, for a site through the interval , is the only occurrence at or above 19 ppm-hrs within the nearly year W126 index values across the eleven 3-year durations extending back in time from 2013 for which the fourth-excessive metric for a similar monitor location is at or below 70 ppb. This is clearly an isolated occurrence.
The EPA does not agree with the commenter’s statements regarding the connection between the two metrics. We have not, as said by the commenter, claimed there to be “congruence” between the two metrics (e.g., ALA et al., p. 196), or that the 2 metrics coincide exactly. Rather, at any location, values of both metrics are a reflection of the temporal distribution of hourly O3 concentrations throughout the year and both differ in response to adjustments in that distribution. While the EPA’s air high quality evaluation reveals that the precise relationship differs amongst particular person websites, it documents an overall robust, positive, non-linear relationship between the two metrics (Wells, 2014a, p. 6, Figures 5a and 5b; Wells, 2015b). Further, this analysis finds the amount of yr-to-year variability in the two metrics tended to lower over time with reducing O3 concentrations, especially for the W126 metric, as described in part IV.E.4 of the proposal (Wells, 2014a; Wells, 2015b). The majority of feedback on the W126 index concurred with its use for assessing O3 exposures, whereas some commenters additionally expressed the view that this index must be used as the form of the secondary commonplace (as discussed in part IV.C.2.d beneath). Most submissions from state and local environmental companies or governments, in addition to organizations of state companies, that provided feedback on the magnitude of cumulative exposure, in terms of the W126 index, appropriate to contemplate for a revised secondary standard, really helpful that the EPA focus on an index value throughout the EPA’s proposed vary of thirteen to 17 ppm-hrs, as did the trade commenters.