Tag Archives: Lisa Jackson

EPA’s New Ozone Rule: Part 14

Posted on January 10, 2013 | 1 comment

In my previous post, we discussed the role of an assessment EPA had done estimating how many children from 12 metropolitan areas would be exposed to different levels of ozone. We’ll close this discussion of why the EPA chose the primary standard it did with these final comments from Jackson, taken from the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011. In this comment, she compares the exposure assessment we were discussing in the previous post to the assessment of risk of how many people are likely to experience health problems from ozone at different maximum levels. She still comes to the conclusion that a standard of .070 ppm is warranted but not lower than that (p. 182):

In considering the estimates provided by the risk assessment, the Administrator notes that significant reductions in health risks for lung function, respiratory symptoms, hospital admissions and mortality have been estimated to occur across the standard levels analyzed, including 0.084 ppm, the level of the 1997 standard, 0.080, 0.074, 0.070, and 0.064 ppm. In looking across these alternative standards, as discussed above in section II.A.2, the patterns in risk reductions are similar to the patterns observed in the exposure assessment for exposures at and above the health benchmark levels. In considering these results, the Administrator recognizes there is increasing uncertainty about the various concentration-response relationships used in the risk assessment at lower O3 concentrations, such that as estimated risk reductions increase for lower alternative standard levels so too do the uncertainties in those estimates. In light of this and other uncertainties in the assessment, the Administrator concludes that the risk assessment reinforces the exposure assessment in supporting a standard level no higher than 0.070 ppm, but it does not warrant selecting a lower standard level.

CASAC asserted that the ozone standard should be set between .060 and .070 ppm, but it preferred that the standard be set closer to 0.060. Jackson agreed with CASAC with its assertion but not with its preference, and she explains why (p. 183):

With regard to selecting a standard level from within that range, the Administrator observes that CASAC recognized that she must make a public health policy judgment to select a specific standard that in her judgment protects public health with an adequate margin of safety. The Administrator notes that CASAC found the relative strength of the evidence to be weaker at lower concentrations, and that their recommended range of 0.060 to 0.070 ppm allowed her to judge the appropriate weight to place on any uncertainties and limitations in the science in selecting a standard level within that range (Samet, 2011, p.9). The Administrator further notes that CASAC expressed the view that selecting a level below the current standard, closer to 0.060 ppm, would be “prudent,” in spite of the uncertainties (Samet, 2011, p.7-8), and that selecting a standard level at the upper end of their recommended range would provide “little” margin of safety (Samet, 2011, p.2).

In reaching her public health policy judgment, after carefully considering the available evidence and assessments, the associated uncertainties and limitations, and the advice and views of CASAC, the Administrator judges that a standard set at 0.070 ppm appropriately balances the uncertainties in the assessments and evidence with the requirement to protect public health with an adequate margin of safety for susceptible populations, especially children and people with lung disease. In so doing, she also concludes that a standard set at a lower level would be more than is necessary to protect public health with an adequate margin of safety for these susceptible populations. This judgment by the Administrator appropriately considers the requirement for a standard that is neither more nor less stringent than necessary for this purpose and recognizes that the CAA [Clean Air Act — MHK] does not require that primary standards be set at a zero-risk level, but rather at a level that reduces risk sufficiently so as to protect public health with an adequate margin of safety. Further, this judgment is consistent with and supported by the advice and unanimous recommendation of CASAC to set a standard within a range that included but was no higher than 0.070 ppm.

So there you have it. The proposed standard of 0.070 ppm was not based on a mathematical equation or a set of rigid criteria. It was a judgement call, something with which reasonable people can disagree.

So far, we’ve been discussing the rationale of EPA’s primary ozone standard, meant to safeguard the pubiic health. Next, we’ll discuss the secondary standard, formulated to help preserve property and other economic interests.

1 Comment

Posted in EPA's New Ozone Rule

Tagged , , , , , , ,

EPA’S New Ozone Rule: Part 13

Posted on January 6, 2013 | 2 comments

The EPA did an assessment estimating how many children in general and asthmatic children in particular, living in 12 metropolitan areas, engaged in moderate and greater exertion in areas that reached a particular maximum level of ozone, would actually be exposed to specific levels of ozone or higher (called benchmarks). The results of the assessment are summarized in the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011 (pp. 51 – 52) as Table 1, which appears below. EPA’s table footnotes appear at the end of this post.

The caption in bold is taken directly from the document (p. 51). The table follows. EPA’s footnotes appear after the end of this post:

Table 1. Number and Percent of All and Asthmatic School Age Children in 12 Urban Areas Estimated to Experience 8-Hour Ozone Exposures At and Above 0.060 and 0.070 ppm While at Moderate or Greater Exertion, One or More Times Per Season Associated with Just Meeting Alternative 8-Hour Standards Based on Adjusting 2002 and 2004 Air Quality Data1,2

Benchmark Levels of Exposures of Concern(ppm) 8-Hour Air Quality Standards3 (ppm) All Children, ages 5-18
Aggregate for 12 urban areas
Number of Children Exposed (% of all children)
[Range across 12 cities, % of all children]		 Asthmatic Children, ages 5-18 Aggregate for 12 urban areas Number of Children Exposed (% of group)[Range across 12 cities, % of group ]

2002 2004 2002 2004
0.074 770,000 (4%)
[0 – 13%]		 20,000 (0%)
[0 – 1%]		 120,000 (5%)
[0 – 14% ]		 0 (0%)
[0 – 1%]
0.070 0.070 270,000 (1%)
[0 – 5%]		 0 (0%)
[0%]		 50,000 (2%)
[0 – 6%]		 0 (0%)
[0 – 1%]
0.064 30,000 (0.2%)
[0 – 1%]		 0 (0%)
[0%] 		10,000 (0.2%)
[0 – 1%]		 0 (0%)
[0%]
0.074 4,550,000 (25%)
[1 – 48%] 		350,000 (2%)
[0 – 9%] 		700,000 (27%)
[1 -51%]		 50,000 (2%)
[0 – 9%]
0.060 0.070 3,000,000 (16%)
[1 – 36%]		 110,000 (1%)
[0 – 4%]		 460,000 (18%)
[0 – 41%]		 10,000 (1%)
[0 – 3%]
0.064 950,000 (5%)
[0 – 17%]		 10,000 (0%)
[0 – 1%]		 150,000 (6%)
[0 – 16%]		 0 (0%)
[0 – 1%

An example on how to read the chart: Look at the benchmark level of 0.070 ppm on the leftmost column of the chart, then at the 8-hour quality standard of 0.074 ppm in the next column. In 2002, 4% of all children ages 5 – 18 in areas whose maximum ozone reached 0.074 ppm were actually exposed to levels of 0.070 ppm or greater (the rest might have been indoors when the ozone level was so high and so escaped exposure). In 2004, less than 1% were so exposed. In 2002, 5% of asthmatic children were so exposed, but in 2004, less than 1% were so exposed. Within brackets are the ranges of minimum and maximum percents encountered in the survey. For example, regarding areas that reached a maximum level of 0.074 ppm in 2002, the lowest percentage encountered of all children exposed to ozone levels of 0.070 ppm or higher was less than 1%. The highest percentage encountered was 13%. The percentage of all children in the 12 cities was 4%.

Jackson explains how the exposure assessment results influenced her judgement (p.179):

In considering the exposure assessment results, the Administrator focused on the extent to which alternative standard levels within the proposed range of 0.060 to 0.070 ppm would likely limit exposures at and above the health benchmark levels of 0.070 and 0.060 ppm for all [school age children] and asthmatic school age children in the 12 urban areas included in the assessment… In particular, the Administrator notes that the 0.070 ppm benchmark level reflects the information that asthmatics likely have larger and more serious effects than healthy people at any given exposure level, such that studies done with healthy subjects may underestimate effects for susceptible populations. Thus, in considering the strong body of evidence from the large number of controlled human exposure studies showing O3-related respiratory effects in healthy people at exposure levels of 0.080 ppm and above, the Administrator concludes it is appropriate to give substantial weight to estimates of exposures at and above the 0.070 ppm benchmark level. With regard to the 0.060 ppm benchmark level, the Administrator notes that this benchmark reflects additional consideration of the evidence from the Adams studies at the 0.060 ppm exposure level. In considering the important but limited nature of this evidence, the Administrator concludes it is appropriate to give some weight to estimates of exposures at and above the 0.060 ppm benchmark level, while recognizing that the public health significance of such exposures is appreciably more uncertain than for the 0.070 ppm benchmark level.

Adopting a standard of 0.070 ppm ozone would be advantageous as it would limit exposure to the 0.070 ppm benchmark (p. 179).

Considering the exposure information shown in Table 1 above in light of these considerations, the Administrator observes that a standard set at 0.070 ppm would likely very substantially limit children’s exposures at and above the 0.070 ppm benchmark, considering both the year-to-year variability and the city-to-city variability in the exposure estimates across the 12 cities included in the assessment. In particular, for the more recent year in the assessment, which had generally better air quality, such exposures were essentially eliminated, whereas in the earlier year with generally poorer air quality, exposures at and above the benchmark level were limited to approximately 2% of asthmatic children in the aggregate across the 12 cities, ranging from 0% up to 6% in the city with the least degree of protection. In weighing this information and in judging the public health implications of these exposure estimates, the Administrator recognizes that only a subset of this susceptible population with exposures at and above the benchmark level would likely be at risk of experiencing O3-related health effects.

Even better, A standard of 0.070 ppm would be effective at limiting exposure down to the 0.060 ppm benchmark (p. 180):

With regard to the 0.060 ppm benchmark level, a standard set at 0.070 ppm would likely also limit exposures at and above this benchmark level, but to a lesser degree. For example, as shown above in Table 1, for the more recent year, exposures at and above the 0.060 ppm benchmark level were limited to approximately 1% of asthmatic children in the aggregate, whereas for the earlier year approximately 18% of asthmatic children were estimated to experience exposures at and above this benchmark level. In weighing this information and judging the public health implications of these exposure estimates, the Administrator recognizes that relative to the 0.070 ppm benchmark, an even smaller, but unquantifiable subset of this susceptible population with exposure at and above the 0.060 ppm benchmark would likely be at risk of experiencing O3-related health effects, and that there is greater uncertainty as to the occurrence of such effects based on the limited evidence available from the Adams studies. The Administrator also notes that these estimates are substantially below the exposures that would likely be allowed by the 0.075 ppm standard (which would be somewhat higher than the estimates in Table 1 for a 0.074 ppm standard).

But then again, adopting the lower 0.064 ppm standard would be even better, according to the assessment (p. 181):

In also considering exposure estimates for the lowest alternative standard level considered in the exposure assessment, 0.064 ppm, the Administrator notes that the estimates of exposures at and above both health benchmark levels are even lower than for a 0.070 ppm standard. For example, for all years in the assessment, exposures of asthmatic children at and above the 0.070 ppm benchmark were essentially eliminated for a 0.064 ppm standard; even in the year with generally poorer air quality and in the city with the least degree of protection, exposures at and above the benchmark level were very substantially limited to approximately 1% of asthmatic children. Further, exposures of asthmatic children at and above the 0.060 ppm benchmark were also essentially eliminated in the more recent year for a 0.064 ppm standard, while in the year with generally poorer air quality such exposures were appreciably limited to approximately 6% of asthmatic children.

Well, in that case, why not go for the 0.064 ppm standard? (p. 181)

In considering these results, the Administrator notes that in its most recent advice, CASAC considered the public health significance of reductions in exposures above these benchmark levels of concern. In so doing, CASAC observed that while the predicted number of exposures of concern increases at every standard level as the benchmark level of concern is reduced, the public health impact of this increase becomes less certain, and that the public health significance of such exposures is difficult to gauge (Samet, 2011, p. 13). The Administrator also notes that CASAC judged that in terms of exposures above the 0.060 ppm benchmark level of concern, a further reduction in the standard from 0.070 ppm is estimated to have a small public health impact, although, in the absence of a threshold at the benchmark level of concern, this analysis is likely to be an underestimate of the true public health impact.

Jackson comes to her final conclusion (p. 181):

Taken together, in weighing this exposure information and judging the public health implications of the exposure estimates for the alternative standard levels, the Administrator finds that a standard of 0.070 ppm appropriately limits exposures of concern relative to the 0.070 and 0.060 ppm benchmark levels for the susceptible population of asthmatic children, as well as for the broader population of all children. Particularly in light of the relatively more uncertain public health implications of exposure at and above the 0.060 ppm benchmark, the Administrator concludes the exposure assessment provides support for a standard no higher than 0.070 ppm, but does not warrant selecting a standard set below that level.

Table Footnotes as Published by the EPA:

  1. Moderate or greater exertion is defined as having an 8-hour average equivalent ventilation rate > 13 l-min/m2.
  2. Estimates are the aggregate results based on 12 combined statistical areas (Atlanta, Boston, Chicago, Cleveland, Detroit, Houston,Los Angeles, New York, Philadelphia, Sacramento, St. Louis, and Washington, D.C.). Estimates are for the ozone season which is all year in Houston, Los Angeles and Sacramento and March or April to September or October for the remaining urban areas.
  3. All standards summarized here have the same form as the 8-hour standard established in 1997 which is specified as the 3-year average of the annual 4th highest daily maximum 8-hour average concentrations must be at or below the concentration level specified. As described in the 2007 Staff Paper (EPA, 2007a, section 4.5.8), recent O3 air quality distributions have been statistically adjusted to simulate just meeting the 0.084 ppm standard and selected alternative standards. These simulations do not represent predictions of when, whether, or how areas might meet the specified standards. As shown in Table 1, aggregate estimates of exposures of concern for the 12 urban areas included in the assessment are considerably larger for the benchmark level of 0.060 ppm O3, comparedto the 0.070 ppm benchmark level. Substantial year-to-year variability is observed in the number of children estimated to experience exposures of concern at and above both the 0.060 and 0.070 ppm benchmark levels. As shown in Table 1, aggregate estimates of exposures of concern at and above a 0.060 ppm benchmark level.

2 Comments

Posted in EPA's New Ozone Rule

Tagged , , , , , ,

EPA’s New Ozone Rule: Part 12

Posted on January 3, 2013 | 1 comment

In my last post, we quoted the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011, where the current Administrator of the EPA, Lisa Jackson (who recently announced she is leaving the agency) discusses why she decided to lower the maximimum ozone concentration limit from 0.075 ppm to between 0.060 and 0.070 ppm. Now she will explain to us how she chose the exact limit. Note that she tacitly acknowledges that she can’t demand more than is necessary. Choosing the optimal number won’t be easy, because the evidence doesn’t point to any such number (p. 174):

The Administrator next considered what standard level within the proposed range of 0.060 to 0.070 ppm would be requisite to protect public health, including the health of susceptible populations, with an adequate margin of safety — i.e., a level that is sufficient but not more than necessary to achieve that result. She recognizes that neither the health evidence nor the human exposure and health risk assessments provide any “bright line” for selecting a specific level within the proposed range.

She explains the difficulties: no laboratory studies in the range of .060 to .070 ppm, studies of people in the street indicate no particular threshold within this range, difficulty in extrapolating what we know about healthy people to people with asthma, and risk assessments made at only two levels: 0.070 ppm and 0.064 ppm. In short, no easy method of determining the best limit. Instead, she will need to base her judgement on many factors taken together (Note: The paragraph sign in brackets [¶] indicates a paragraph break that I introduced that isn’t in the original document. P. 174):

[¶]No controlled human exposure studies were conducted at intermediate levels between 0.070 and 0.060 ppm. Associations reported in epidemiological studies generally ranged from well above to well below this range, with no suggestion of a possible threshold within this range. While there is substantial evidence that asthmatics have greater responses than healthy, non-asthmatic people, there is uncertainty about the magnitude of the differences in their responses within this range. Moreover, within this range, exposure and health risk assessments estimated the exposures of concern and health risks only for standard levels of 0.070 and 0.064 ppm. Thus, there is a combination of scientific evidence and other information that the Administrator needs to consider as a whole in making the public health policy judgment to select a standard level from within the proposed range.

The Administrator declares the limit she selected (p. 175):

After weighing the strengths and the inherent uncertainties and limitations in the evidence and assessments, and taking into account the range of views and judgments expressed by the CASAC Panel, including CASAC’s most recent advice, and in the public comments, as discussed above, the Administrator finds the evidence and other information on the public health impacts from exposure to O3 warrant an 8-hour primary standard set at 0.070 ppm [emphasis mine — MHK]…

Jackson notes that the surest source of evidence, laboratory studies, offer scant evidence below the 0.080 ppm level other than the studies of Adams. In the interest of brevity I’m omitting that section. She goes on to discuss epidemiological studies, studies of people in the street. While they may not be as robust as laboratory studies, the large number of studies do offer enough evidence of a link between levels of ozone and bad health outcomes to make a judgement (p. 177):

With regard to epidemiological studies, the Administrator observes that statistically significant associations between ambient O3 levels and a wide array of respiratory symptoms and other morbidity outcomes, including school absences, emergency department visits, and hospital admissions, have been reported in a large number of studies. These associations occur across distributions of ambient O3 concentrations that generally extend from above to well below the proposed range, although the Administrator recognizes that there are questions of biological plausibility in attributing the observed effects to O3 alone at the lower end of the concentration ranges extending down to background levels.

However, Jackson does recognize that epidemiological studies have their drawbacks, as she discusses here. Samet assures her that although these studies are less reliable at concentrations that approach the natural ambient level, they are not less reliable at the 0.060 to 0.070 ppm range (p. 177):

[¶] The Administrator also recognizes the uncertainty inherent in translating information from such studies into the basis for selecting a specific level from within the proposed range. The Administrator notes that in its most recent advice, CASAC concluded that epidemiological studies are inherently more uncertain as ambient O3 concentrations decrease and effect estimates become smaller, although CASAC’s confidence in attributing reported effects on health outcomes to O3 did not change over the range of 0.060 to 0.070 ppm (Samet, 2011. p.10-11).

Now Jackson must make a value judgement. At what level concentration is the epidemiological evidence pointing to? (p. 178)

[¶]In weighing this evidence and the related uncertainties, the Administrator concludes that while the epidemiological evidence provides support for a standard set no higher than 0.070 ppm, it does not warrant selecting a lower standard level within the proposed range.

But what about people with respiratory problems? Perhaps they need a standard below 0.070 ppm. but she concludes that there is not enough information to choose a lower limit for that reason (p. 178).

The Administrator has also considered the evidence from controlled human exposure and epidemiological studies that children and adults with asthma and other lung diseases are likely to experience larger and more serious responses to O3 exposures than healthy, non-asthmatic people. … the Administrator recognizes that controlled human exposure studies conducted using healthy subjects likely underestimate effects in this susceptible population. The Administrator also recognizes, however, that there is uncertainty about the magnitude of any such differences in responses. Thus, the Administrator concludes that while this evidence supports taking into consideration the extent to which a standard would limit exposures of susceptible populations to concentrations at and above the 0.070 and 0.060 ppm benchmark levels, it does not further inform the translation of the available evidence of O3– related effects in healthy subjects into the basis for selecting any specific standard level from within the proposed range.

Perhaps some quantifiable data can shed some light on an appropriate level that will assist people with respiratory problems. That is the subject of my next post.

1 Comment

Posted in EPA's New Ozone Rule

Tagged , , , , , , , ,

EPA’s New Ozone Rule: Part 11

Posted on September 13, 2012 | 1 comment

In 2008, the EPA under Administrator Stephen Johnson revised the primary ozone standard to 75 ppb. He was succeeded the next year by Lisa Jackson, the appointee of the incoming Obama administration. Soon after, the EPA began its reconsideration of the new ozone standard, and Ms. Jackson decided to revise the standard, lowering it to 70 ppb.

Her rationale is recorded in the EPA document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011, pages 61 through 186. In this section, Jackson’s positions are summarized, then comments from interested parties appear together with EPA’s responses. A short piece summarizes the comments of the Clean Air Scientific Advisory Committee (CASAC), followed by the rationale for the final decision. A second section, pages 192 through 296, describes the rationale for the secondary standard, the standard meant to protect property and other interests.

It’s a lot to read, and I can’t say I read every word. However, the impression from what I did read was that Jackson wasn’t in possession of any evidence that Johnson didn’t have. Rather, she placed different weight on the evidence. What Johnson saw as sufficient to lower the primary standard to 75 ppb and no further, Jackson felt compelled to lower the standard down to 70 ppb. Here is the summary section “Conclusions on the Level of the Primary Standard”, page 167 ff., with my comments interspersed. The frequent references to Samet are to a 67-page letter written to Jackson in March 2011 from Dr. Jonathan M. Samet, chair of CASAC with the subject line Clean Air Scientific Advisory Committee (CASAC) Response to Charge Questions on the Reconsideration of the 2008 Ozone National Ambient Air Quality Standards. If you wish to read the letter, click here.

Note: The paragraph sign in brackets [¶] indicates a paragraph break that I introduced that isn’t in the original document.

To begin, let’s read what the Jackson set out to do in EPA’s own words:

As a result of the reconsideration, the Administrator has determined that a different level of the primary O3 standard than the 0.075 ppm level set in 2008 is requisite to protect public health with an adequate margin of safety. For the reasons discussed below, the Administrator has decided to set the level of the 8-hour primary O3 at 0.070 ppm…

What influenced her to make this decision?

In the 2010 proposal, the Administrator [Jackson — MHK] concluded it was appropriate to propose to set the primary O3 standard below 0.075 ppm. This conclusion was based on the evidence and exposure/risk-based considerations … and the Administrator’s determination that 0.075 ppm was a level at which the evidence provides a high degree of certainty about the adverse effects of O3 exposure on healthy people. The Administrator’s public health policy judgment on the proposed range for the level of the primary O3 standard was framed by the evidence and exposure/risk-based considerations discussed above in this notice and informed by the following key observations and conclusions on the controlled human exposure and epidemiological studies and the results of the human exposure and health risk assessments.

She will now state four reasons why the evidence suggests that the standard should be lowered (p. 168).

(1) There is a strong body of evidence from controlled human exposure studies evaluating healthy people at O3 exposure levels of 0.080 ppm and above that demonstrated lung function decrements, respiratory symptoms, pulmonary inflammation, and other medically significant airway responses. Newly available for the 2008 review, there is the limited but important evidence of lung function decrements and respiratory symptoms in healthy people down to O3 exposure levels of 0.060 ppm…

I believe Johnson had this same evidence. I suspect that if we sat the two administrators together, they would argue about the importance of limited evidence. When is limited evidence important evidence?

(2) A large number of epidemiological studies [studies that look at people in the street, not in the laboratory — MHK] have reported statistically significant associations between ambient O3 levels and a wide array of respiratory symptoms and other morbidity outcomes including school absences, emergency department visits, and hospital admissions. More specifically, positive and robust associations were found between ambient O3 concentrations and respiratory hospital admissions and emergency department visits… across distributions of ambient O3 concentrations that extend well below the 2008 standard level of 0.075 ppm…

The above is a powerful statement, which if true, would give good cause to lower the standard. But I would want to know what the contribution to morbidity outcomes is made by ambient O3 concentrations in the 0.075 – 0.070 ppm range. This is what we need to balance against any economic cost.

The next reason concerns people with respiratory problems and diseases. Note the concern that studies that look at only healthy people may be underestimating the effects of ozone on those with respiratory problems, although by how much is unknown:

(3) There is substantial evidence … indicating that children and adults with asthma and other preexisting lung diseases are at increased risk from O3 exposure… Evidence from controlled human exposure studies indicates that asthmatics are likely to experience larger and more serious effects in response to O3 exposure than healthy people. This evidence indicates that … controlled human exposure studies of lung function decrements and respiratory symptoms that evaluate only healthy, non-asthmatic subjects likely underestimate the effects of O3 exposure on asthmatics and other people with preexisting lung diseases. However, there is uncertainty about the magnitude of the differences in their responses such that we are not able to quantify the magnitude of any such differences.

Finally, a statement of confidence that lower ozone levels will improve public health:

(4) The assessments of exposures of concern and risks for a range of health effects indicate that important improvements in public health are very likely associated with O3 levels just meeting alternative standard levels evaluated in these assessments, especially for the alternative levels of 0.070 and 0.064 ppm, relative to levels at and above 0.075 ppm…

Now the following paragraph leads me to believe that Jackson did not base her decision on evidence that Johnson did not have. Rather, she interpreted the same evidence differently and was more accepting of CASAC’s recommendations (p. 171):

These observations and conclusions led the Administrator to propose to set the primary O3 standard at a level in the range of 0.060 to 0.070 ppm. In so doing she placed significant weight on the information newly available in the 2008 review that had been reviewed by CASAC, and took into consideration public comments that had been received during the 2008 review. She also placed significant weight on CASAC’s conclusion that important public health protections can be achieved by a standard set below 0.075 ppm, within the range of 0.060 to 0.070 ppm.

Here the document acknowledges the considerations that led Johnson to establish the 0.075 ppm standard, noting the value judgements he made (p. 171):

In reaching a final decision on the level of the primary O3 standard, the Administrator again considered whether the standard level of 0.075 ppm set in the 2008 final rule is sufficiently below 0.080 ppm to be requisite to protect public health with an adequate margin of safety. In considering this standard level, the Administrator looked to the rationale for selecting this level presented in the 2008 final rule… In that rationale, EPA observed that a level of 0.075 ppm is above the range of 0.060 to 0.070 ppm recommended by CASAC, and that the CASAC Panel appeared to place greater weight on the evidence from the Adams studies and on the results of the exposure and risk assessments, whereas EPA placed greater weight on the limitations and uncertainties associated with that evidence and the quantitative exposure and risk assessments. Additionally in 2008, EPA’s rationale did not discuss and thus placed no weight on exposures of concern relative to the 0.060 ppm benchmark level. Further, EPA concluded that “[a] standard set at a lower level than 0.075 ppm would only result in significant further public health protection if, in fact, there is a continuum of health risks in areas with 8-hour average O3 concentrations that are well below the concentrations observed in the key controlled human exposure studies and if the reported associations observed in epidemiological studies are, in fact, causally related to O3 at those lower levels. Based on the available evidence, [EPA] is not prepared to make these assumptions.” (73 FR 16483).

Now Jackson is going to state where she disagrees with Johnson. This strengthens my impression that the decision to lower the limit was a judgement call about which reasonable people can differ (p. 172):

In reconsidering the entire body of evidence available in the 2008 rulemaking, including the Agency’s own assessment of the epidemiological evidence in the 2006 Criteria Document, the views of CASAC, including its most recent advice (Samet, 2011), and the public comments received on the 2010 reconsideration proposal, the Administrator finds no basis to change her conclusion that important and significant risks to public health are likely to occur at a standard level of 0.075 ppm. Thus, she judges that a standard level of 0.075 ppm is not sufficient to protect public health with an adequate margin of safety. In support of this conclusion, the Administrator finds that setting a standard that would protect public health, including the health of susceptible populations, with an adequate margin of safety should reasonably depend upon giving some weight to the results of the Adams studies and EPA’s analysis of the Adams’s data, and some weight to the results of epidemiological studies of respiratory morbidity effects that may extend down to levels below 0.060 ppm.

A limit of outdoor ozone concentration set at level X actually protects people from effects below X, since people spend much of their time indoors where ozone levels are naturally lower. Since they are likely to be indoors when the ozone level reaches X, their maximum exposure to ozone will probably be to levels much below X. Jackson’s argument here is that if setting the limit at 0.070 ppm will limit people’s exposure to ozone levels above 0.060 ppm:

[¶]Moreover, the Administrator concludes that, in setting such a standard, consideration should be given to how effectively alternative standard levels would serve to limit exposures of concern relative to the 0.060 ppm benchmark level as well as the 0.070 ppm benchmark level, based on EPA’s exposure and risk assessments…

So far, Jackson has explained why she feels that the limit of 0.075 ppm is inadequate. She wants to take CASAC’s recommendation of a limit between 0.060 and 0.070 ppm. But she needs to select an exact number. In my next post, she’ll explain how she did that.

1 Comment

Posted in EPA's New Ozone Rule

Tagged , , , , , , ,

Topic: The EPA’s New Ozone Rule Part I

Posted on September 25, 2011 | 2 comments

Welcome to the very first topic of this blog, The EPA’s New Ozone Rule. It’s a rather long topic, consisting of 24 posts. If you arrived at this post via a link, you can navigate between posts using the arrows that appear above each post heading. Click on the right arrow (→) to go to the next post. Click on the left arrow (←) to go to the previous post.

On September 2, 2011, the White House released a statement that President Obama had requested the Director of the Environmental Protection Agency (EPA) Lisa Jackson to withdraw a recent EPA proposal to tighten standards for ground-level ozone1.  This proposal would lower the maximum allowable concentration of ground-level ozone from the current standard set in 1997 of 0.08 parts per million (ppm)2 3 to somewhere in a range between 0.060 and 0.070 ppm4.

This change in policy evoked cheers from political conservative and business circles and outrage from the environmental community. Jack Gerard, president of the American Petroleum Institute, was quoted by the newspaper USA Today as saying, “The president’s decision is good news for the economy and Americans looking for work. EPA’s proposal would have prevented the very job creation that President Obama has identified as his top priority.”5 The same article quotes Michael Steel, spokesperson for Speaker of the House John Boehner as saying, “We’re glad that the White House responded to the speaker’s letter and recognized the job-killing impact of this particular regulation.”6 On the other hand, environmentalists were furious. Gene Karpinski, president of the League of Conservation Voters, was quoted by the USA Today article as saying, “The Obama administration is caving to big polluters at the expense of protecting the air we breathe. This is a huge win for corporate polluters and huge loss for public health.”7  Conservatives and business interests, then, see the new rule as an undue burden on business. Environmental groups regard the rule as vital in protecting the public health. Who is correct?

It is possible that both sides have valid points and that the truth lies somewhere between them. I suspect that the rule would place a heavy burden on business, but not as heavy as its opponents make it out to be. Similarly, the rule would probably contribute to public health, although not as critically as its proponents think it will. Perhaps it would be wise to delay implementing the rule, but not to postpone it indefinitely.

I hope in my next postings to analyze the proposed rule, spell out exactly what claims are being made for it, and examine closely the claims of its opponents.

Footnotes:

  1. Statement by the President on the Ozone National Ambient Air Qualities Standards. White House website. To view, click here.
  2. National Ambient Air Quality Standards. EPA website. To view, click here.
  3. The 1997 standard is widely quoted as being 0.084 ppm rather than 0.08 ppm. This is because the EPA only demands an accuracy of 0.01 ppm. Therefore, any reading of ozone concentration between 0.075 ppm and 0.084 ppm would be rounded to 0.08 ppm and be considered in compliance. However, a reading of 0.085 ppm would be rounded to 0.09 ppm and would not be considered in compliance. Practically speaking then, 0.084 is the highest reading possible that remains in compliance. See EPA’s March 2008 National Ambient Air Quality Standards for Ground-Level Ozone: General Overview, p. 3. To view, click here. By the way, this is an excellent review of the case against ground-level ozone.
  4. Federal Register Vol. 75 No. 11, p. 2938 Tuesday, January 19, 2010. Docket no. EPA-HQ-OAR-2005-0172. To view, click here.
  5. USA Today, “Obama decides against tougher ozone standards” September 2, 2011, paragraph 14. To view, click here.
  6. Ibid. Paragraph 7
  7. Ibid. Paragraph 26

2 Comments

Posted in EPA's New Ozone Rule

Tagged , , , , , ,