Category Archives: EPA’s New Ozone Rule

EPA’s New Ozone Rule: Part 24

This last post about EPA’s new ozone rule will summarize the topic and will draw some conclusions. We begun with a September 2011 news item that the Obama administration had requested the EPA to withdraw a new proposal to reduce the maximum amount of ground-level ozone in the air:    from 75 ppb to 70 ppb (.075 ppm to .070 ppm)1. This decision stirred controversy with many in the business community praising the President for keeping economic concerns front and center against many in the environmental community claiming that the President had missed an important opportunity to improve air quality2. Our purpose was to determine which side held more weight.

The answer to that question depends a great deal on one’s sense of priorities: is a robust economy more important or is reducing sickness and death from air pollution to a minimum more important? We know that ozone is a respiratory irritant, lethal in high concentrations but damaging even in very low concentrations3. We have ample research that shows higher ground-level ozone concentrations causes more deaths and results in more visits to hospital emergency rooms and missed days from work4. On the other hand, minimizing ozone creation is an expensive proposition. Requiring industry, responsible for most ground-level ozone production, to reduce its ozone contribution is laying on it a heavy regulatory burden that hampers business activity and reduces employment5.

We discussed the origins and chemistry of ground-level ozone and saw why industry would need to bear most of the burden of lowering the standard6. We noted that the new rule actually imposed two standards, a primary standard based on highest averages to protect human health, and a secondary standard based on cumulative exposure to protect property and economic interests, particularly plant life7.

We talked about the damage that ozone does to people and property8, then went on to discuss the history of ozone regulation since 20089. We went into some detail into EPA’s thinking as recorded in government documents, trying to understand why they set the primary standard as .075 ppm in 2008 but .070 only two years later10, and why they originally did not really set a secondary standard but later formulated one on the insistence of CASAC (Clean Air Scientific Advisory Committee)11. We saw that the two administrators, Stephen Johnson under President Bush and Lisa Jackson under President Obama, had access to about the same evidence but came to very difficult conclusions about what was needed to protect the public health and leave an adequate margin for error12. We saw how CASAC strongly objected to not having a separate secondary standard and how they influenced the EPA to adopt such a standard in 201013. We discussed the burden of implementation and touched on the many industries that are effected by tougher ozone rules14. We did a very rough cost-benefit analysis weighing the financial benefits of stricter ozone regulation against its economic costs to society15.

Finally, we discussed how well current ozone rules are being implemented, what areas of the country are not in compliance with the current standard of 75 ppb, and by how much16. We saw that non-attainment of the current EPA standard is confined largely to the East and West Coasts and to major metropolitan areas. Only California has severe problems with ozone, and it has those problem in a large swath through the state. Baltimore and Dallas have moderate problems, and the rest of the country have at most marginal problems with ozone.

So where does that leave us? Should the EPA try to implement a stricter standard at a later date? President Obama himself stated in his September 2011 statement that the ozone standard would be reconsidered in 2013, so perhaps this year we will see a second attempt. But maybe not: Lisa Jackson left the EPA last February, and until the Senate confirms a successor, the EPA will be headed by an acting administrator (Bob Perciasepe). I understand that an acting director does not have the same authority as an administrator confirmed by the Senate, so I doubt that the EPA will adopt a stricter standard until a new Administrator is confirmed (Obama’s current nominee is Gina McCarthy).

I don’t disagree with Obama’s decision to request a retraction. Business opposition to the new rule was strong. He was facing a difficult election and he didn’t need to stir up more opposition than he had to. As we discussed earlier, deciding whether the ozone standard should be at 75 ppb or 70 ppb is largely a judgement call. The lower standard will save lives, increase life expectancy, and relieve illness, but will likely be an economic burden and an impediment to job creation. Reasonable people could take either side of the argument.

I tend to fall on the side of environmentalists. While the regulatory burden is a concern, people and economies adjust over time, as long as burden is reasonable. If a tougher standard was enforced, I think we would see some loss of economic activity and employment. But when regulations are enforced in an intelligent way, people eventually get used to them and learn to work within them. For example, take EPA’s Acid Rain Program, legislated in 1990 as part of the Clean Air Act and put into effect in 199517. The Acid Rain Program is a cap-and-trade program, enabling industries that are able to cut their sulfur dioxide emissions beneath a certain limit to sell the rights to emit the saved sulfur dioxide to other industries. This program may have played a major role in sharply reducing emissions in the U.S.18 People seem to have adjusted to it, with very little vocal opposition that I am aware of. Nobody has blamed the Acid Rain Program for the poor state of the economy.

But the key is that stricter standards must be intelligently enforced with sensitivity to the needs of business; heavy-handed regulation blindly administered with no regards to business can really be a drag on the economy. Not being an expert, I’m not sure how to do intelligent enforcement. However, I understand that Obama’s current nominee for EPA Administrator, Gina McCarthy, is a strong believer in working with business to find the best solutions to environmental problems. If so, she’d be perfect for the job, and I strongly urge the Senate to confirm her as soon as possible.

Yet the stricter standard was scuttled. I think part of the problem is that EPA’s manner can be rather imperious and somewhat patronizing, laying down new regulations without any serious input from other stakeholders. There was a period of public comment to which the agency responded19, but my impression is that the agency merely rebutted criticism rather than try to incorporate people’s concerns into the decision process. Naturally, affected stakeholders are resentful. As it writes a new standard into law, the EPA needs to build cooperation with stakeholders, and that was what was sorely lacking in the process. Everybody’s concerns need to be addressed and it’s important they feel their needs are being addressed.

Moreover, EPA tried to enact the new standard without garnering public support first. When I first learned of Obama’s retraction, I had never heard of the new ozone rule, and I doubt many people did, either. Many people were wondering, what is this bothersome new regulation all about and why is it important? EPA can still win a stricter ozone standard, but to accomplish that it must first raise awareness about the problems of ground-level ozone among the public. It can do this by working with environmental advocacy organizations and patient advocacy organizations (such as the American Lung Association) to build public awareness of ground-level ozone and its effects. Either it or a surrogate can build a major ad campaign to push ozone to the forefront of the national consciousness (how about the slogan “Ozone Kills!”). It can devise educational presentations that schools can use in their classrooms. It can put scientists and researchers on news programs and talk shows. It can have them write articles and op-ed pieces in newspapers and popular magazines. If there is a popular demand for stricter ozone standards, there will be a much better chance that the standards will make it into law.

I’ve wondered how ozone levels affect the performance of players in major league sports, particularly those played out-of-doors (baseball and football especially). If a negative correlation could be proved, we might have major league sports as allies. Players are occasionally accused of taking performance-enhancing drug. What if it could be proved that low-ozone air is a performance-enhancing drug that is perfectly legal?

Also, we need more research into ozone. I mentioned before that very few scientific studies have looked at the effects of 40 — 60 ppb ozone on subjects in the laboratory20. It also seems that there is a dearth of laboratory studies that have had asthmatics and other COPD (chronic obstructive pulmonary disease) sufferers as subjects21. We need more of these studies. We need to publicize epidemiological studies that compare the effects of living in areas of the country with high ozone concentrations with those of lower concentrations to convince people there is a difference, and that it affects them personally.

As for the secondary standard, I’d hold off on that. If the purpose of the secondary standard was to shore up struggling ecosystems and prevent species extinction, it would be worth fighting for. But if its main purpose is to protect property, then why should we be fighting for the concerns of property owners? We ought to educate people as to what a secondary standard can accomplish, but it shouldn’t be our responsibility to try to impose it. That should be for the beneficiaries, home owners, property owners, and farmers to demand. If they lobby EPA for it or if Congress pushes for it, the EPA should consider it. But if no stakeholders think they need such a standard, then we really don’t need it and we shouldn’t be pursuing it. With a world full of environmental threats, we need to choose our battles carefully, and this is a battle not worth fighting. We need to save our time, energy, and effort for where it is more needed.

So those are my conclusions and recommendations, which you can accept or reject as you see fit. Thank you for taking the time to read this topic, and I hope you found it helpful to understand an important public health issue.


  1. Statement by the President on the Ozone National Ambient Air Qualities Standards. White House website. To view, click here.
  2. See my post The EPA’s New Ozone Rule: Part 1. To view it, click here.
  3. See my post The EPA’s New Ozone Rule: Part 7. To view it, click here. See also my blog pages Ozone Excerpts 1, which you can view here, and Ozone Excerpts 2, which you can view here.
  4. For example, see the six papers listed in my post The EPA’S New Ozone Rule: Part 22, which you can view by clicking here.
  5. I admit I’m on very shaky ground here: I haven’t actually seen a scientific study on the economic effects of regulation. Perhaps I’ve bought too deeply into the arguments of conservative Republicans and the Tea Party. But it makes sense that if companies are forced to spend large amounts of money, time, and effort on government regulations, they will have less resources to spend on their business and less money to pay employees. The regulations may be necessary or even vital, but there’s always a cost. Of course, the net cost to the world economy is lessened because money spent on regulation benefits other businesses. The net cost to the U.S. economy is lessened, too, if money spent on conforming to regulations is spent on U.S. businesses.
  6. See my post The EPA’s New Ozone Rule: Part 4, which you can view by clicking here.
  7. See my posts The EPA’s New Ozone Rule: Part 6, which you can view by clicking here, and The EPA’s New Ozone Rule: Part 15, which you can view by clicking here.
  8. See my post The EPA’s New Ozone Rule: Part 7. To view it, click here. See also my blog pages Ozone Excerpts 1, which you can view here, and Ozone Excerpts 2, which you can view here. As for the damage that ozone causes property, I haven’t really discussed that in any depth. However, in Ozone Excerpts 1, see Table 1-2: Summary of ozone causal determination for welfare effects, vegetation, and ecosystem effects. In Ozone Excerpts 2, see Table 2-2: Summary of ozone causal determinations for vegetation and ecosystem effects.
  9. See my post The EPA’s New Ozone Rule: Part 8. To view it, click here.
  10. See my posts The EPA’s New Ozone Rule: Part 10 through Part 14. You can view any of these posts by clicking on the following:     Part 10,     Part 11,     Part 12,     Part 13,     Part 14.
  11. See my posts The EPA’s New Ozone Rule: Part 15 through Part 18. You can view any of these posts by clicking on the following:     Part 15,     Part 16,     Part 17,    Part 18.
  12. For Administrator Stephen Johnson’s view, see my post The EPA’s New Ozone Rule: Part 10 which you can view by clicking here. For Administrator Lisa Jackson’s view, see my posts The EPA’s New Ozone Rule: Part 11, click here to view, and The EPA’s New Ozone Rule: Part 12, click here to view.
  13. See my posts The EPA’s New Ozone Rule: Part 17. To view it, click here.
  14. See my posts The EPA’s New Ozone Rule: Part 20 and Part 21. To view Part 20, click here. To view Part 21, click here.
  15. See my post The EPA’s New Ozone Rule: Part 22. To view it, click here.
  16. See my post The EPA’s New Ozone Rule: Part 23. To view it, click here.
  17. U.S. Environmental Protection Agency website, Clean Air Markets Acid Rain Program. To view, click here.
  18. For example, U.S. Environmental Protection Agency, Acid Rain and Related Programs: 2009 Highlights, 15 Years of Results 1995 to 2009. To review the report, click here.
  19. For example, U.S. Environmental Protection Agency, National Ambient Air Quality Standards for Ozone, July 2011, Section II.C.2. “Comments on the Proposed Decision”, pp. 77 – 163.
  20. See my post The EPA’s New Ozone Rule: Part 9. To view it, click here.
  21. This observation was made from inference. The U.S. Envronmental Protection Agency’s document National Ambient Air Quality Standards for Ozone, July 2011, states (p.38) “The most certain evidence of adverse health effects from exposure to O3 comes from the controlled human exposure studies, as discussed in the 2010 proposal in section II.A.2, and the large bulk of this evidence derives from studies of exposures at levels of 0.080 ppm and above. At those levels, there is consistent evidence of lung function decrements and respiratory symptoms in healthy young adults, as well as evidence of inflammation and other medically significant airway responses.” Later on, the document mentions the Adams studies at the only controlled studies “that examine respiratory effects associated with prolonged O3 exposures at levels below 0.080 ppm.” But the Adams studies only used healthy subjects. Thus, the number of controlled studies using subjects with COPD and other respiratory ailments must be few and far between.

EPA’s New Ozone Rule: Part 23

An important part of this discussion must be how successful the EPA has been in implementing the current ozone standard of 75 ppb set in 2008. If many areas of the country are not in compliance, or as the EPA puts it, in non-attainment, then it becomes questionable whether we should be pursuing a stricter standard. We need to attain the current standard first before moving to something stricter. On the hand hand, if EPA has acheived the current standard in most places, then perhaps it is time to attempt something more ambitious.

The answer to this question might be ambiguous. Take a look at EPA’s web page Classifications of 8-Hour Ozone (2008) Nonattainment Areas which you can view by clicking here. This web page lists areas in non-attainment in five categories: extreme, severe 15, serious, moderate, and marginal. The areas in the first three categories are all in California. Two non-California areas are in the moderate category: Baltimore and Dallas/Ft. Worth. Where ozone problems exist outside of California, they are nearly all in the least severe category, the marginal category.

This information is displayed graphically on a map, which you can view by clicking here. Large areas of California have a particularly severe ozone problem. Otherwise, mild-to-moderate ozone non-attainment is concentrated on the Northeast Corridor and many major metropolitan areas: Buffalo, Pittsburgh, Cleveland, Columbus, Cincinnatti, Chicago, St. Louis, Charlotte, Knoxville, Atlanta, Memphis, Baton Rouge, Houston, Dallas, Denver, Phoenix, and the Upper Green River Basin area in Wyoming. Ground-level ozone, not surprisingly, is a problem of cities. Even so, most cities are in the marginal category, which indicates if just a little more was done to reduce ozone in these cities, they would attain the 75 ppb standard.

So an argument can be made both ways. One can argue that more work needs to be done to reach the 75 ppb standard before we attempt something more ambitious, or one can argue that we have nearly attained the 75 ppb standard (except for California) and that it is time to work towards saving even more lives.

In my next post, I will present my own conclusions and recommendations, which you are free to accept or reject.

EPA’s New Ozone Rule: Part 22

The goal of our discussion is a cost-benefit analysis. What benefits would lower ozone bring us, how much would it cost, and do the benefits justify the costs? These questions are addressed in two EPA documents:

  • Final Ozone NAAQS Regulatory Impact Analysis (March 2008). To view, click here.
  • Regulatory Impact Analysis Final National Ambient Air Quality Standard for Ozone (July 2011), which is a supplement to the March 2008 document. To view, click here.

As these documents are at the heart of our discussion, I really should take the time to read and understand them thoroughly. But my time being short and the documents together totalling 645 pages, unfortunately I can’t do them justice. But you can read them, and I can point to certain highlights that can give us food for thought.

These papers can be challenged. But critics who would argue with their conclusions can’t just glibly dismiss their claims out of hand. They need to demonstrate that either their assumptions or their methods are wrong. They need to argue the issue with the same level of detail that these documents do.

What attracted my attention most were a few charts in the beginning of the July 2011 document. The first chart, Table S1.1 on page 6 of the document, lists the costs and benefits of ozone and PM2.5 (particles suspended in the air 2.5 microns in diameter and larger) reduction. Please open up the chart by clicking here.

Let’s describe the elements of the chart. There are three main rows, each row showing the costs and benefits of each of three possible limits on ground-level ozone: 0.075 ppm, 0.070 ppm, and 0.065 ppm. Each row is divided in half: the upper half for multi-city analyses, the lower half for meta-analyses, where the authors did not collect raw data but rather gathered data from other studies. Each half-row sites statistics from three studies: six studies in all. The studies, listed in order of appearance in the chart by author’s name are:

  • Bell, M.L. et al, 2004, Ozone and short term mortality in 95 US urban communities, Journal of the American Medical Association 292(19) 2372-2378. For the article, click here.
  • Schwartz, J., 2005, How sensitive is the association between ozone and daily deaths to control for temperature?American Journal of Respiratory and Critical Care Medicine, Vol. 171(6):627-631. For the article, click here.
  • Huang, Y., F. Dominici, M.L. Bell, 2005, Bayesian Hierarchical Distributed Lag Models for Summer Ozone Exposure and Cardio-Respiratory Mortality, Environmetrics, 16, 547-562. For the article, click here.
  • Bell, M.L., F. Dominici, J.M. Samet, 2005, A meta-analysis of time series studies of ozone and mortality with comparison to the national morbidity, mortality, and air pollution studies, Epidemiology, 16(4):436-445. For the abstract, click here.
  • Ito, K., S.F. DeLeon, M. Lippmann, 2005, Associations between ozone and daily mortality: analysis and meta-analysis, Epidemiology 16(4):446-457. For the article, click here.
  • Levy, J.L., S.M. Chemerynski, J.A. Sarnat, 2005, Ozone exposure and mortality: analysis and meta-analysis, Epidemiology 16(4):458-468. For the abstract, click here.

There are three major columns in the chart: total benefits, total costs, and net benefits (total benefits minus total costs). Total benefits and net benefits are divided into two half-columns: 3% discount rate and 7% discount rate. I don’t really understand what these are, but I can guess from what I’ve read. As I understand it, social discount rates are the rates of return one could expect if money spent on a social good was invested in financial markets instead. Let’s say you invested a large amount of money in 200 mutual funds chosen at random. Some funds would get a high rate of return, some a low rate of return, but over 10 years time, the rate of return would likely average out to some figure no matter what funds you chose. This rate of return is what we call the social discount rate.

Now the author prepared the chart showing amounts in 2006 dollars that would accrue in 2020. That suggests to me that the author is asking: if we go to a lower ozone standard in 2006, what are the costs and benefits we can expect in 2020? We can expect adopting a stricter ozone standard to cost us so much in 2007. If instead of adopting the stricter standard, we immediately invested that money instead at a 3% or a 7% rate of return, how much money would we get in 2020? We do the same for costs in 2008 and 2009 and so on. We would also see benefit in 2007. We can estimate the financial value of that benefit (harder to do than determining costs) and ask the same question: if we immediately invested that money at a 3% or 7% rate of return, how much money would we get in 2020? We do the same for benefits in 2008 and 2009 and so on. We sum up the financial returns from costs and benefits, and compare the results.

Now if you look at the numbers, you’ll see that for each combination of ozone limit, type of study (multi-city vs. meta-analysis) and cost/benefit column (for example, costs estimated for an ozone limit of 0.075 ppm, multi-city analyses) that the numbers in the combination are quite close to each other; the differences between the studies are not great. I took the average of each combination and put them into a condensed chart. I also calculated the size and midpoint of each net benefit range. Figures are in billions of 2006 dollars. A negative net benefit is a net cost.

Ozone Limit Study Type Total Benefits Total Costs Net Benefits Net Benefits Range Net Benefits Midpoint
0.075 ppm Multi-city 6.9 to 14.3 7.6 to 8.8 -1.9 to 6.7 8.6 2.4
0.075 ppm Meta-analysis 8.7 to 16.2 7.6 to 8.8 -0.20 to 8.4 8.6 4.1
0.070 ppm Multi-city 13.2 to 27.3 19.0 to 25.0 -11.8 to 8.3 20.1 -1.8
0.070 ppm Meta-analysis 18.7 to 33.2 19.0 to 25.0 -6.0 to 14.2 20.2 4.1
0.065 ppm Multi-city 22.2 to 44.8 32.0 to 44.0 -22.0 to 12.7 32.7 -4.6
0.065 ppm Meta-analysis 32.3 to 54.7 32.0 to 44.0 -11.7 to 23.0 34.7 5.6

What I found interesting about these numbers is that total costs are the same for each limit of ozone both for the multi-city studies and the meta-analyses. However, for total benefits and net benefits, the meta-analyses are consistently higher than the multi-city studies.

Also interesting is that the range of estimation of net benefits widens as the ozone limit gets lower. The range is $8.6 billion for 0.075 ppm, about $20 billion for 0.070 ppm, and about $33 billion for 0.060 ppm. That tells me that as the ozone limit gets lower, there is more uncertainty in estimating costs and benefits.

Now if you look at the midpoints of the ranges, the midpoints for the meta-analyses are fairly consistent: about $4 – $5 billion. But the midpoints of the ranges for the multi-city analyses go down as the ozone limit gets lower: from a net benefit of $2.4 billion for 0.075 ppm to a net cost of $1.8 billion for 0.070 ppm and then finally to a net cost of $4.6 billion for 0.065 ppm. But even the meta-analyses predict high net costs at the lower end of their ranges: up to $6 billion for 0.070 ppm and up to $11.7 for 0.065 ppm.

This tells me that as we choose lower limits for ozone, the uncertainty of estimating what the net benefit will be increases as well as the risk that the net benefit will be negative (i.e. really be a net cost). Of course, this evaluation depends on how much financial value we attach to a human life.

But it is also important to consider the benefits alone. If the benefits were purely financial, then it would make sense to be very utilitarian and forget about those benefits if they were outweighed by costs. But if those benefits are in a substantial number of lives saved and illnesses alleviated, then they become much more desirable, even urgent. Even if the economics dictate that it is wiser not to pursue those benefits now, they can remain in our sights as a goal we want to achieve eventually.

Following the table we just discussed is Table S1.2: Summary of Total Number of Ozone and PM2.5‐Related Premature Mortalities and Premature Morbidity Avoided: 2020 National Benefits, page 8 of the document. Please open the chart now by clicking here.

According to this chart, the number of lives that can be saved by both reducing ozone and particulate matter 2.5 microns and larger is substantial. To put it in perspecitve, on 9/11 2,753 New Yorkers were killed. Surely, if we were aware of a plot by Al Qaeda to kill 4000 Americans, we would expect our government to react. If we can save that many lives by protecting them from air pollution, shouldn’t we try?

There is one more topic we need to discuss on this subject, and that is compliance.

EPA’s New Ozone Rule: Part 21

As we continue to look at the costs and benefits of lowering the standard on ground-level ozone, let’s get an idea what industry would need to do to comply. As we mentioned before, ozone is rarely emitted directly by industry. Rather, industry emits volatile organic compounds (VOCs), and atmospheric chemistry and sunlight act on these VOCs to produce ozone1. To reduce ground-level ozone, industry must reduce the VOCs that it emits.

This is not an easy thing to do, considering the vast array of applications that VOCs arise from. To give an idea of how many industries are affected, I copied EPA’s list of documents recommending how different industries can cut down their VOC emissions, called control techniques guidelines (CTGs) and alternative control techniques (ACTs)2. The methods they describe are called reasonably available control technologies (RACTs), because they are not difficult to obtain at reasonable cost. Many of these documents are from the 1970’s, 80’s, and 90’s and may be seriously out of date. Nevertheless, the extent of industrial processes described by these documents give us an appreciation for the breadth of effort and the depth of commitment required from the business community to reduce ozone.

Some of technologies may not be hard to implement. One of the shorter documents addresses the technology of cutback asphalt, which is asphalt dissolved in an organic solvent3. This allows the asphalt to be sprayed as a liquid on a road bed. The solvent evaporates into fumes that can generate ozone, and the asphalt is left behind to harden into road surface. To eliminate these fumes, the EPA recommends switching to emulsion asphalt, which is asphalt finely ground and mixed with water. Like cutback asphalt, emulsion asphalt can also be sprayed onto road beds where it will harden, but the evaporated water will not generate ozone. Emulsion asphalt can be manufactured with the same equipment, so road construction companies can switch to emulsion asphalt at little additional cost.

Other technologies are no longer needed over time. A federal regulation required that gasoline stations put hoods on their pump nozzles to prevent the escape of gasoline fumes. In May 2012, the EPA rescinded that regulation when it was advised that current car construction already prevent gasoline fumes from escaping during refueling without need of a hood4.

Here is a list of CTGs and ACTs taken from the EPA website SIP Planning Information Toolkit: Control Techniques Guidelines and Alternative Control Techniques Documents, which you can view by clicking here. As you can see, the list of industries that need to adapt to new ozone rules is long, which helps to explain the large-scale economic impact of new ozone regulations:

Control Technology Guidelines (CTGs)

  • Gasoline service stations
  • Surface coating operations
  • Surface coatings of cans, coils, paper, fabrics, automobiles, and light-duty trucks.
  • Solvent metal cleaning
  • Refinery vacuum producing systems, wastewater separators, and process unit turnarounds
  • Tank truck gasoline loading terminals
  • Surface coating of metal furniture
  • Surface coating of insulation of magnetic wire
  • Surface coating of large appliances
  • Bulk gasoline plants
  • Storage of petroleum liquids in fixed-roof tanks
  • Cutback asphalt
  • Surface coating of miscellaneous metal parts and products
  • Factory surface coating of flat wood paneling
  • Petroleum refinery equipment
  • Manufacture of synthesized pharmaceutical products
  • Manufacture of pneumatic rubber tires
  • Graphic arts: Rotogravure and Flexography
  • Petroleum Liquid Storage in External Floating roof tanks
  • Gasoline tank trucks and vapor collection systems
  • Large petroleum dry cleaners
  • Manufacture of high-density polyxxx resins
  • Natural gas/gasoline processing plants
  • Leaks from synthetic organic chemical polymer and resin manufacturing equipment
  • Air oxidation processes in synthetic organic chemical manufacturing industry
  • Wood furniture manufacturing operations
  • Ship building and ship repair operations
  • Aerospace
  • Industrial cleaning solvents
  • Offset lithographic and letterpress printing
  • Flexible package printing
  • Flat wood paneling coatings
  • Paper, film, and foil coatings
  • Large appliance coating
  • Metal furniture coatings
  • Miscellaneous metal and plastic pants coatings
  • Fiberglass boat manufacturing materials
  • Miscellaneous industrial adhesive
  • Automobile and light-duty truck assembly coatings

Alternate Control Technologies (ACTs)

  • Surface coating operations at shipbuilding and ship repair facilities
  • Plywood veneer dryers
  • Applications of traffic markings
  • Ethylene oxide sterilization of fumigation operation
  • Halogenated solvent cleaners
  • Organic wast process vents
  • Polystyrene foam manufacturing
  • Bakery ovens
  • Industrial wastewater
  • Agricultural pesticides
  • Volatile organic liquid storage in floating and fixed-roof tanks
  • Batch processes
  • Industrial cleaning solvents
  • Surface coating of automotive/transportation and business machine plastic parts
  • Automotive refinishing
  • NOx emissions from nitric and adipic acid manufacturing plants
  • NOx emissions from stationary combustion turbines
  • NOx emissions from process heaters
  • NOx emissions from stationary internal combustion engines
  • NOx emissions from cement manufacturers
  • NOx emissions from industrial, commercial, and institutional boilers
  • NOx emissions from utility boilers
  • NOx emissions from glass manufacturers
  • NOx emissions from iron and steel mills
  • Automobile refinishing



  1. To review the chemistry of ozone generation, see my post in this blog EPA’s New Ozone Rule: Part 4.
  2. EPA website, SIP Planning Information Toolkit: Control Techniques Guidelines and Alternative Control Techniques Documents. To view, click here.
  3. U.S. Environmental Protection Agency, Control of Volatile Organic Compounds from Use in Cutback Asphalt, December 1977. To view, click here.
  4. CNN website, EPA to remove vapor-capturing rubber boot from gas pump handles by Todd Sperry, May 10, 2012. To view, click here. See also the television program The Rachel Maddow Show, MSNBC; click here for the video.

EPA’s New Ozone Rule: Part 20

Had the EPA succeeded in lowering the primary standard to 70 ppb and introducing a secondary standard of 13 ppm-hours, how much would that have cost industry? Would the benefits of a stricter standard justify that cost?

Here I must confess that I am at a considerable disadvantage. I do not know how to estimate industry costs, although I can report on other people’s claims. If I had all the time I needed, I would interview as many businesspeople I could on how tighter ozone restrictions imposed in 1998 affected them. In particular, I would want to know what new equipment they needed to buy to comply with the new standards. Did the new standards affect their decisions to buy equipment they were going to buy anyway and in what manner? How much more did they feel obliged to spend because of the new standards? Alas, time is short, I’m not getting paid to do this, I have no training in estimating costs, and I feel the need to move on to new topics. But these are still very important questions.

What I really would like is to compare three versions of one state’s State Implementation Plan (SIP). The first version would be designed to comply with the 0.084 ppm standard, the second with the 0.075 ppm standard, and the third to comply with the 0.070 ppm standard. Where are they the same? Where are they different? What are businesses expected to do differently to comply with the stricter standards? What kind of equipment are they expected to acquire under the three standards?

Do the benefits of a stricter standard justify the costs? Critics didn’t think so, such as the organization Americans for Tax Reform quoting a report by Oklahoma Senator James Inhofe:

EPA itself estimated that its ozone standard would cost $90 billion a year, while other studies have projected that the rule could cost upwards of a trillion dollars and destroy 7.4 million jobs.1

A couple of comments on this. The $90 billion a year figure and the trillion dollar figure are not contradictory. If the rule would cost us $90 billion a year for a dozen years, that will cost us more than a trillion dollars. Both figures are the upper limits of ranges, so that $90 billion a year and $1 trillion overall may be worst-case scenarios. According to a chart produced by the EPA which I will present in a later post, going to a 0.070 ppm standard would cost between $19 and $25 billion 2006 dollars by 20202. It is important to note that nobody can know for sure just how much the rule will cost either in money or in jobs. What experts do is estimate a range wide enough so that they think they will be right 95% of the time (95% confidence interval). That is to say, if an expert made an estimate of a range in twenty circumstances, in 19 times the true numbers will fall somewhere within those ranges.

Also, it should be pointed out that lowering ozone limits brings economic benefits in terms of lower medical costs and increased worker productivity (mainly because employees are out sick less). This is brought home by another EPA chart which estimates that if we had gone to a 0.070 ppm standard in 2011, we could have saved 170,000 sick days from work and eliminated 6,600 visits to the hospital and emergency rooms2. That all needs to be subtracted from the economic cost.

And what is the meaning of the destruction of 7.4 million jobs? Does that mean 7.4 million layoffs or 7.4 million people not hired who otherwise would be, or is it a combination of both? How does one determine how many jobs will be lost? (Note that Senator Inhofe is claiming two-digit accuracy: 7.4 million jobs, not 7.3 million or 7.5 million, so he is claiming more accuracy than a mere rough estimate. That kind of accuracy comes from a calculation and not just from a guess.) Do we need to balance that figure against jobs that might be created by the new rule, for example if companies that produce antipollution equipment saw an upsurge in business?

I am not an economist, but I think that the cost to business needs to be put into two categories. There are purchases that companies must make to comply with the new rule. The money doesn’t disappear; it merely goes somewhere else. If businesses buy American pollution control equipment, that is not a loss to the U.S. economy. Then there is the loss of productivity or efficiency that can come with compliance. That really could mean destroyed wealth, although it may be justified by the health and other benefits of the new rule.

Also, it is important to distinguish between capital expenditures, money spent on equipment, and operating expenses, money spent on operating that equipment. Money spent on equipment is a one-time investment, whereas money spent on operating that equipment is an ongoing commitment.

The EPA produced two very important documents that do a thorough cost-benefit analysis: Final Ozone NAAQS Regulatory Impact Analysis, March 2008, and its updated addendum, Regulatory Impact Analysis Final National Ambient Air Quality Standard for Ozone, July 2011. We will discuss these two documents in the next post.


  1. Website of Americans for Tax Reform, EPA Regulation of the Day: Ozone Rule. To view, click here.
  2. See my post in this blog EPA’s New Ozone Rule: Part 22.

EPA’s New Ozone Rule: Part 19

Next, we discuss the implementation of EPA’s standards. How are they implemented now, and if EPA had instituted tougher standards, what exactly would change?

The EPA does not usually enforce standards directly. Rather, individual states draw up State Implementation Plans (SIPs) to comply with EPA’s standards, and EPA approves them. Only when a state refuses to submit a SIP will the EPA step in and impose a Federal Implementation Plan (FIP)1. My impression is that imposition of FIPs are relatively rare and that almost all states eventually comply, although tardily at times. I did find discussions of FIPs to be imposed on Hawaii2, the Navajo Nation in Arizona3, and the Fort Berthold Indian Reservation in North Dakota4.

Nevetheless, many states do tend to be late with their SIPs. On January 4, 2013, the EPA announced that 25 states and two territories had failed to submit to their SIPs to the EPA: Arkansas, California, District of Columbia, Hawaii, Iowa, Kansas, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New York, North Dakota, Oklahoma, Pennsylvania, Puerto Rico, South Dakota, Utah, Vermont, Washington State, Wisconsin, and Wyoming. Three other states, Arizona, Illinois, and New Mexico, have submitted incomplete SIPs5. I had heard that as a rule, state governments resent the intrusion of the Federal government, so I’m not surprised.

To access an individual state’s SIP, you can go to that state’s environmental agency website and search for it there. You can also go to the EPA website, click on the state on the map featured prominently on the home page, and search for the SIP there. Note: Not all state sites will have the SIP, and if they do have it, it may be a summary rather than the actual text (an example of this is the SIP for New York State6). Finally, you can go to the State Implementation Plan page for Region 2, which you can view by clicking here. (I think there was some sort of mix-up on the webmaster’s part, because this page should be the website for all SIPs.)

In fact, this is how the page describes SIPs:

A State Implementation Plan (SIP) is the federally approved and enforceable plan by which each state identifies how it will attain and/or maintain the health-related primary and welfare-related secondary National Ambient Air Quality Standards (NAAQS) described in Section 109 of the Clean Air Act (CAA) and 40 Code of Federal Regulations 50.4 through 50.12. It may be helpful to view a SIP as a state’s blueprint for clean air. The process of developing a SIP starts when the state develops a draft SIP that contains control measures and strategies, proposes it in a public process, formally adopts it, and submits it to EPA by the Governor’s designee. EPA must take formal rulemaking action to approve or disapprove a SIP, and once approved by EPA a SIP is included in the Code of Federal Regulations (Title 40, Part 52) and becomes federally enforceable. From time to time a state may choose to revise its SIP or EPA may require a state to revise its SIP. EPA is required to take rulemaking action on SIP revisions as well as SIPs…

SIP documents contain a wide variety of information including air quality goals, measurements of air quality, emission inventories, modeling demonstrations, control strategies, evidence of public participation, and more. While EPA is working toward making SIP documents fully accessible electronically, our initial effort is focused on ensuring EPA-approved SIP regulations are available for each state, commonwealth or territory. Fully electronically accessible SIPs will become a reality for future SIP actions as EPA fully automates the rulemaking process through EDocket in the coming months. In the meantime, EPA will continue to present currently approved state regulations and add information to the site periodically.

On this page you will see a map of the United States; click on one of 10 regions on a map. Each region leads to a different web page, which lists links to individual state pages. Each state page is different and will present information and links in different ways.

For example, click on Region 5 (Great Lakes states). You’ll see the Region 5 Air and Radiation page. Click on “View All SIPS by state”. Now click on the arrow by Minnesota. This is the list of SIP topics that appears:

Approved State Implementation Plan Provisions, 1 record
Chapter 7005 – Definitions And Abbreviations — 2 records
Chapter 7007 – Permits And Offsets — 42 records
Chapter 7009 – Ambient Air Quality Standards — 18 records
Chapter 7011 – Standards For Stationary Sources — 11 records
Chapter 7011 – Standards For Stationary Sources — 86 records
Chapter 7017 – Monitoring And Testing Requirements — 41 records
Chapter 7019 – Emission Inventory Requirements — 11 records
Emission Standards For Inorganic Fibrous Materials — 4 records
Facility-Specific Restrictions — 31 records
Incinerators — 20 records
Liquid Petroleum And Volatile Organic Liquid Storage Vessels — 21 records
Monitoring, Testing, And Reporting Requirements — 8 records
Motor Vehicles — 7 records
Nitric Acid Plants — 2 records
Notification And Emission Inventory Requirements — 11 records
Open Burning Statutes — 7 records
Oxygenated Gasoline Statutes — 13 records
Petroleum Refineries — 32 records
Sewage Sludge Incinerators — 11 records
Sulfuric Acid Plants — 14 records
Summary Of Criteria Pollutant Maintenance Plan, 1 record

As you can see, SIPs can be very involved. Now click on the arrow next to “Approved State Implementation Plan Provisions”, then the arrow underneath it next to “Federal Approved State SIP”, then the arrow underneath it next to “(Not Categorized)”, then click underneath it on “SIP Notebook”. You’ll land on EPA’s State Implementations Plan web page for Minnesota. On the bottom, you will see two Adobe icons: they will lead you to the Federal Register where Minnesota’s SIP is published (I believe the left icon leads to the SIP published in February 2005, the right icon leads to revisions made in August 2005).

Seeing how complex government regulations can be, I feel a certain amount of sympathy for those business people who rail against government regulations. Certainly, regulations should never be more complicated or onerous than they absolutely need to be. Yet we depend on these regulations to keep our water safe to drink and our air safe to breathe.

A crucial question is how would the SIPs change if the primary ozone standard was lowered to 70 ppb and if a secondary standard of 13 ppm-hour was introduced? How would the SIPs change to meet the new standards, and how much more would industry need to do to meet the SIPs? Those are complex questions to which I have found no answers, at least not yet.


  1. EPA website, Ozone Implementation – Programs and Requirements for Reducing Ground Level Ozone. To view, click here.
  2. EPA website, Air Actions, Hawaii. To view, click here.
  3. EPA website, Air Actions, Navajo Nation. To view, click here.
  4. EPA website,Federal Implementation Plan for Oil and National Gas Production Facility on the Fort Berthold Indian Reservation. To view, click here.
  5. EPA Factsheet (PDF format), Final Notice: Findings of Failure to Submit a Complete State Implementation Plan for Section 110(a) Pertaining to the 2008 Ozone NAAQS. To view, click here.
  6. EPA website, New York State Implementation Plan (SIP) Summaries. To view, click here.

EPA’s New Ozone Rule: Part 18

In our last post, we saw how EPA’s CASAC reacted strongly to its decision to make the secondary standard of ground-level ozone identical to the primary standard. That influenced EPA to reconsider its decision as reported in the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011 (p. 215):

In reconsidering the 2008 final rule in the 2010 proposal, the Administrator agreed with the conclusions drawn in the 2006 Criteria Document, 2007 Staff Paper and by CASAC that the scientific evidence available in the 2008 rulemaking continues to demonstrate the cumulative nature of O3 – induced plant effects and the need to give greater weight to higher concentrations. Thus, the Administrator concluded that a cumulative exposure index that differentially weights O3 concentrations represents a reasonable policy choice for a secondary standard to protect against the effects of O3 on vegetation during the growing season. The Administrator further agreed with both the 2007 Staff Paper and CASAC that the most appropriate cumulative, concentration-weighted form to consider is the sigmoidally weighted W126 form.

As EPA noted before, the amount of protection the primary standard would give to vegetation is uncertain, but the hint is that EPA is now prepared to err on the side of regulation. In this excerpt (p. 216), EPA argues that we can’t be sure that the primary standard can protect vegetation as well as the W126 standard. A comparison is hard to make because the results of such a comparison would likely differ from year to year, and because we don’t have enough data in the areas where the secondary standard might do the most good, in rural areas. (The paragraph sign [¶] indicates a paragraph break that I introduced that wasn’t there in the original text. The “8-hour average standard” is the primary standard, which averages ozone readings taken during an eight-hour period.):

The Administrator noted that… EPA proposed a second option of revising the then-current 8-hour average secondary standard by making it identical to the proposed 8-hour primary standard. The 2007 Staff Paper analyzed the degree of overlap expected between alternative 8-hour and cumulative seasonal secondary standards using recent air quality monitoring data. Based on the results, the 2007 Staff Paper concluded that the degree to which the current 8-hour standard form and level would overlap with areas of concern for vegetation expressed in terms of the 12-hour W126 standard is inconsistent from year to year and would depend greatly on the level of the 12-hour W126 and 8-hour standards selected and the distribution of hourly O3 concentrations within the annual and/or 3-year average period.

¶ The 2007 Staff Paper also recognized that meeting the then current or alternative levels of the 8-hour average standard could result in air quality improvements that would potentially benefit vegetation in some areas, but urged caution be used in evaluating the likely vegetation impacts associated with a given level of air quality expressed in terms of the 8-hour average form in the absence of parallel W126 information. This caution was due to the concern that the analysis in the 2007 Staff Paper may not be an accurate reflection of the true situation in non-monitored, rural counties due to the lack of more complete monitor coverage in many rural areas. Further, of the counties that did not show overlap between the two standard forms, most were located in rural/remote high elevation areas which have O3 air quality patterns that are typically different from those associated with urban and near urban sites at lower elevations. Because the majority of such areas are currently not monitored, there are likely to be additional areas that have similar air quality distributions that would lead to the same disconnect between forms. Thus, the 2007 Staff Paper concluded that it remains problematic to determine the appropriate level of protection for vegetation using an 8-hour average form. [emphasis mine — MHK]

Now here is the real rationale behind the secondary rule: cumulative exposure hurts plants more than it hurts humans. But why that should be? That question I can’t answer. The document continues (p. 217):

The Administrator also noted in the 2010 proposal that CASAC recognized that an important difference between the effects of acute exposures to O3 on human health and the effects of O3 exposures on welfare [of vegetation — MHK] is that vegetation effects are more dependent on the cumulative exposure to, and uptake of, O3 over the course of the entire growing season (Henderson, 2006c). The CASAC O3 Panel members were unanimous in concluding the protection of natural terrestrial ecosystems and managed agricultural crops requires a secondary O3 standard that is substantially different from the primary O3 standard in form, averaging time, and level (Henderson, 2007).

That concludes the EPA’s rationale in the document. Again, it seems to me that the decision was based on a judgement call. You may agree with me that there is less of a moral imperative to safeguard property and crops than there is safeguarding human life, so when evaluating the secondary standard, it makes even more sense to compare gains and losses. True, a secondary standard might improve agricultural crops, but is it worth the additional cost to industry to maintain that standard? That question is especially hard to answer when we don’t know exactly how much benefit the secondary standard would bring us above and beyond the primary standard. It’s a very tricky question. More about this in my final comments on the subject. In the meantime, let’s discuss how EPA standards are implemented.

EPA’s New Ozone Rule: Part 17

In our previous post, the EPA explained why it found a secondary standard necessary to protect vegetation Indeed, when EPA’s Clean Air Scientific Advisory Committee (CASAC) found out, they strongly objected. I can imagine that a journalist reporting on CASAC would use words like “furious”, “enraged”, “livid.” They let the EPA know in no uncertain terms how they felt as reported in the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011 (p. 212):

Following the 2008 decision on the O3 standards, serious questions were raised as to whether the standards met the requirements of the CAA [Clean Air Act — MHK]. In April 2008, the members of the CASAC Ozone Review Panel sent a letter to EPA stating “[i]n our most-recent letters to you on this subject – dated October 2006 and March 2007 – … the Committee recommended an alternative secondary standard of cumulative form that is substantially different from the primary Ozone NAAQS in averaging time, level and form — specifically, the W126 index within the range of 7 to 15 ppm-hours, accumulated over at least the 12 “daylight” hours and the three maximum ozone months of the summer growing season” (Henderson, 2008). The letter continued: “[t]he CASAC now wishes to convey, by means of this letter, its additional, unsolicited advice with regard to the primary and secondary Ozone NAAQS. In doing so, the participating members of the CASAC Ozone Review Panel are unanimous in strongly urging you or your successor as EPA Administrator to ensure that these recommendations be considered during the next review cycle for the Ozone NAAQS that will begin next year” (id.).

Now CASAC is going to really lay into the EPA!

The letter further stated the following views:

The CASAC was … greatly disappointed that you failed to change the form of the secondary standard to make it different from the primary standard. As stated in the preamble to the Final Rule, even in the previous 1996 ozone review, ‘there was general agreement between the EPA staff, CASAC, and the Administrator, … that a cumulative, seasonal form was more biologically relevant than the previous 1-hour and new 8-hour average forms (61 FR 65716)’ for the secondary standard. Therefore, in both the previous review and in this review, the Agency staff and its advisors agreed that a change in the form of the secondary standard was scientifically well-justified.

Unfortunately, this scientifically-sound approach of using a cumulative exposure index for welfare effects was not adopted, and the default position of using the primary standard for the secondary standard was once again instituted. Keeping the same form for the secondary Ozone NAAQS as for the primary standard is not supported by current scientific knowledge indicating that different indicator variables are needed to protect vegetation compared to public health. The CASAC was further disappointed that a secondary standard of the W126 form was not considered from within the Committee’s previously-recommended range of 7 to 15 ppm-hours. The CASAC sincerely hopes that, in the next round of Ozone NAAQS review, the Agency will be able to support and establish a reasonable and scientifically-defensible cumulative form for the secondary standard.” (Henderson, 2008)

Wow! You can almost feel the burning red-hot indignation behind this rhetoric which I suspect was toned down quite a bit. In our next post, we’ll see how the EPA reacted.

EPA’s New Ozone Rule: Part 16

We are continuing our discussion in our last post about why the EPA felt it necessary to formulate a new secondary standard for ground-level ozone concentration. As we noted before, initially the EPA felt it adequate for the secondary standard to be identical to the primary standard, but then it reconsidered its position.

The EPA performed an evaluation comparing primary and secondary standards and found that high cumulative exposures were widespread. Below is a summary of what they found, taken from the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011. Note point #4 where EPA explains why it thinks the primary standard is insufficient (p. 201):

…The following key observations were drawn from comparing predicted changes in interpolated air quality under each alternative standard form and level scenario analyzed:

  1. The results of the exposure assessment indicate that then-current air quality levels could result in significant impacts to vegetation in some areas. For example, [bulleted list is my formatting — MHK]
    • For the base year (2001), a large portion of California had 12-hr W126 O3 levels above 31 ppm-hours, which has been associated with approximately up to 14% biomass loss in 50% of tree seedling cases studies.
    • Broader multi-state regions in the East (NC, TN, KY, IN, OH, PA, NJ, NY, DE, MD, VA) and West (CA, NV, AZ, OK, TX) are predicted to have levels of air quality above the W126 level of 21 ppm-hours, which is approximately equal to the secondary standard proposed in 1996 and is associated with biomass loss levels no greater than approximately 9% in 50% of tree seedling cases studied, and biomass loss levels greater than approximately 9% in the other 50%.
    • Much of the East and Arizona and California have 12- hour W126 O3 levels above 13 ppm-hours which has been associated with biomass loss levels no greater than approximately 7% biomass loss in 75% of tree seedling cases studied and biomass loss levels greater than approximately 7% in the remaining 25% of cases studied.
  2. When 2001 air quality was rolled back to meet the then current 8-hour secondary standard, the overall 3-month 12-hour W126 O3 levels were somewhat improved, but not substantially. Under this scenario, there were still many areas in California with 12-hour W126 O3 levels above 31 ppm hours. A broad multi-state region in the East (NC, TN, KY, IN, OH, PA, MD) and West (CA, NV, AZ, OK, TX) were still predicted to have O3 levels above the W126 level of 21 ppm-hours.
  3. Exposures generated for just meeting a 0.070 ppm, 4th-highest maximum 8-hour average alternative standard (the lower end of the proposed range for the primary O3 standard) showed substantially improved O3 air quality when compared to just meeting the then-current 0.08 ppm, 8-hour standard. Most areas were predicted to have O3 levels below the W126 level of 21 ppm-hr, although some areas in the East (KY, TN, MI, AR, MO, IL) and West (CA, NV, AZ, UT, NM, CO, OK, TX) were still predicted to have O3 levels above the W126 level of 13 ppm-hours.
  4. While these results suggested that meeting a proposed 0.070 ppm, 8-hour secondary standard would provide substantially improved protection in some areas, the Staff Paper recognized that other areas could continue to have elevated seasonal exposures, including forested park lands and other natural areas, and Class I areas which are federally mandated to preserve certain air quality related values. This is especially important in the high elevation forests in the western U.S. where there are few O3 monitors and where air quality patterns can result in relatively low 8-hour averages while still experiencing relatively high cumulative exposures.

Now the EPA will explain where in particular the lack of a separate secondary standard is a problem. It seems that ozone levels in high-elevation rural areas remain fairly constant during the day, so that the ozone concentration may be below the primary standard and yet deliver a large cumulative exposure. This is where attention to a cumulative-based secondary standard might be particularly useful. Note that the 8-hour average form refers to the primary standard, which depends on the average of ozone measurements taken during an eight-hour time period (p. 202):

To further characterize O3 air quality in terms of the 8-hour and alternative secondary standard forms, an analysis was performed in the 2007 Staff Paper to evaluate the extent to which county-level O3 air quality measured in terms of various levels of the 8-hour average form overlapped with that measured in terms of various levels of the 12-hour W126 cumulative, seasonal form. This analysis was limited by the lack of monitoring in rural areas where important vegetation and ecosystems are located, especially at higher elevation sites. This is because O3 air quality distributions at high elevation sites often do not reflect the typical urban and near-urban pattern of low morning and evening O3 concentrations with a high mid-day peak, but instead maintain relatively flat patterns with many concentrations in the mid-range (e.g., 0.05-0.09 ppm) for extended periods. These conditions can lead to relatively low daily maximum 8-hour averages concurrently with high cumulative values so that there is potentially less overlap between an 8-hour average and a cumulative, seasonal form at these sites. The 2007 Staff Paper concluded that it is reasonable to anticipate that additional unmonitored rural high elevation areas important for vegetation may not be adequately protected even with a lower level of the 8-hour form.

Then the EPA seems to reverse its position. Since we can’t be confident that the primary standard will be adequate, especially in rural areas and remote areas where data on ozone might be sparse, we may need to establish a secondary standard. Whereas before the EPA wanted to err on the side of less regulation, now they want to err on the side of more regulation (p. 203):

It continues to remain uncertain as to the extent to which air quality improvements designed to reduce 8-hour O3 average concentrations would reduce O3 exposures measured by a seasonal, cumulative W126 index. The 2007 Staff Paper indicated this to be an important consideration because:

  1. The biological database stresses the importance of cumulative, seasonal exposures in determining plant response;
  2. Plants have not been specifically tested for the importance of daily maximum 8-hour O3 concentrations in relation to plant response;
  3. The effects of attainment of a 8-hour standard in upwind urban areas on rural air quality distributions cannot be characterized with confidence due to the lack of monitoring data in rural and remote areas.

These factors remain important considerations in the Administrator’s reconsideration of whether the current 8-hour form can appropriately provide requisite protection for vegetation.

Question on point #3: If we can’t be sure of the effects of attainment of an 8-hour standard on rural areas because we don’t have enough monitoring data, how would we be any more sure of the effects of attainment of the secondary standard?

The EPA’s own CASAC (Clean Air Scientific Advisory Committee) was also very unhappy with the decision to make the secondary standard equal to the primary standard. We will see what they have to say in the next post.

EPA’ s New Ozone Rule: Part 15

A major innovation of EPA’s 2010 revision of the ozone standard was the introduction of what is called a secondary standard that is different from the primary standard. The secondary standard has existed before, but it was always set identical to the primary standard. To summarize the two standards:

  • The primary standard is intended to protect the public health. It is currently based on the fourth-highest 8-hour average ozone concentration reading in a year.
  • The secondary standard is meant to protect property, economic interests, and other concerns. It is based on a cumulative ozone concentration over time. Ozone readings are taken hourly between 8 a.m. and 7 p.m., adjusted by what is called the W126 rule, and then summed during a three-month period. Units are in ppm-hours. See what I wrote in this blog about the secondary standard in the post “EPA’s New Ozone Rule: Part 6.” To view, click here.

Now if one standard was consistently stricter than the other, the EPA could simply adopt the stricter standard. That it felt necessary to formulate two standards can only mean that in some places one standard will be harder to meet, and in other places the other standard will be the stricter. The EPA wants to meet both standards everywhere, a condition we Orthodox Jews call being machmir for both shitos.

What I don’t understand yet is why the primary standard, which is meant to safeguard public health, is based on a highest one-time average, whereas the secondary standard, meant to protect property, is based on a cumulative measure. A cumulative standard makes sense, because research shows that the extent of damage to plants caused by ozone depends on cumulative exposure. But perhaps damage to human health also depends on cumulative exposure, just as the damage caused by radiation to human health depends on cumulative exposure. Why not make the primary standard cumulative as well? Be that as it may, currently the primary standard remains based on a highest one-time average, while the secondary standard remains identical to the primary standard.

What I want to do in this post is quote EPA in its own words why it felt a new secondary standard was necessary, discussed in the document National Ambient Air Quality Standards for Ozone, Final Preamble, 2011.

From the outset, the EPA is clear that the secondary standard was formulated because of ozone’s effects on plants (p. 196):

…The 2006 Criteria Document concluded that O3 exposure indices that cumulate differentially weighted hourly concentrations are the best candidates for relating exposure to plant growth responses…

It is interesting that the EPA recognized the value of a secondary standard long before 2010 (p. 197):

At the conclusion of the 1997 review, the biological basis for a cumulative, seasonal form was not in dispute. There was general agreement between the EPA staff, CASAC, and the Administrator, based on their review of the air quality criteria, that a cumulative, seasonal form was more biologically relevant than the previous 1-hour and new 8-hour average forms (61 FR 65716).

The EPA also explained why, rather than summing up straight ozone concentrations, it chose to sum up modified values, referred to as the W126 form. Using W126 values gives more weight to higher concentrations and much less weight to lower concentrations that would exist either naturally without human activity, or from foreign sources beyond the control of the U.S. government (p. 198):

Regarding the first consideration, the 2007 Staff Paper noted that the W126 form, by its incorporation of a continuous sigmoidal weighting scheme, does not create an artificially imposed concentration threshold, yet also gives proportionally more weight to the higher and typically more biologically potent concentrations, as supported by the scientific evidence. Second, the index value is not significantly influenced by O3 concentrations within the range of estimated PRB [policy-relevant background, the level of ozone not caused by human activity in the U.S. — MHK], as the weights assigned to concentrations in this range are very small.

Nevertheless, the EPA retained a secondary standard identical to the primary standard until 2010. Initially, the EPA felt that if the primary standard was made more strict, it would be sufficient for the secondary standard were made identical to it. A separate secondary standard that was cumulative would provide no additional protection unless it was made very strict, which can’t be justified because our knowledge of the effects of low-level ozone on vegetation is so uncertain (the paragraph sign [¶] indicates a paragraph break that I inserted. P. 209):

In considering the appropriateness of establishing a new standard defined in terms of a cumulative, seasonal form, or revising the 1997 secondary standard by making it identical to the revised primary standard, … EPA first considered the 2007 Staff Paper analysis of the projected degree of overlap between counties with air quality expected to meet the revised 8-hour primary standard, set at a level of 0.075 ppm, and alternative levels of a W126 standard based on currently monitored air quality data. This analysis showed significant overlap between the revised 8-hour primary standard and selected levels of the W126 standard form being considered, with the degree of overlap between these alternative standards depending greatly on the W126 level selected and the distribution of hourly O3 concentrations within the annual and/or 3-year average period. On this basis, as an initial matter, EPA concluded that a secondary standard set identical to the proposed primary standard would provide a significant degree of additional protection for vegetation as compared to that provided by the then-current 0.084 ppm secondary standard.

¶ In further considering the significant uncertainties that remain in the available body of evidence of O3-related vegetation effects and in the exposure and risk analyses conducted for the 2008 rulemaking, and the difficulty in determining at what point various types of vegetation effects become adverse for sensitive vegetation and ecosystems, EPA focused its consideration on a level for an alternative W126 standard at the upper end of the proposed range (i.e., 21 ppm-hours). The 2007 Staff Paper analysis showed that at that W126 standard level, there would be essentially no counties with air quality that would be expected both to exceed such an alternative W126 standard and to meet the revised 8-hour primary standard – that is, based on this analysis of currently monitored counties, a W126 standard would be unlikely to provide additional protection in any monitored areas beyond that likely to be provided by the revised primary standard.

The EPA states again that with the lack of extensive monitoring in rural areas, it is unsure how much additional protection a separate secondary standard would provide. At this point, it decided to err on the side of less regulation. Note that the term “8 hour standard” refers to the primary standard, which averages readings over eight-hour periods (p. 210):

The EPA also recognized that the general lack of rural monitoring data made uncertain the degree to which the revised 8-hour standard or an alternative W126 standard would be protective in those areas, and that there would be the potential for not providing the appropriate degree of protection for vegetation in areas with air quality distributions that result in a high cumulative, seasonal exposure but do not result in high 8-hour average exposures. While this potential for under-protection using an 8- hour standard was clear, the number and size of areas at issue and the degree of risk was hard to determine. However, EPA concluded at that time that an 8-hour standard would also tend to avoid the potential for providing more protection than is necessary, a risk that EPA concluded would arise from moving to a new form for the secondary standard despite significant uncertainty in determining the degree of risk for any exposure level and the appropriate level of protection, as well as uncertainty in predicting exposure and risk patterns.

…EPA concluded at that time that establishing a new secondary standard with a cumulative, seasonal form would result in uncertain benefits beyond those afforded by the revised primary standard and therefore may be more than necessary to provide the requisite degree of protection.

Eventually, though, the EPA changed its mind. Why will be discussed in the next post.