Tag Archives: cost-benefit analysis

EPA’s New Ozone Rule: Part 22

Posted on February 5, 2013 | 2 comments

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.

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EPA’s New Ozone Rule: Part 21

Posted on February 3, 2013 | 1 comment

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

.

Footnotes:

  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.

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EPA’s New Ozone Rule: Part 20

Posted on January 31, 2013 | 1 comment

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.

Footnotes

  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.

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EPA’ s New Ozone Rule: Part 5

Posted on July 2, 2012 | Leave a comment

On September 2, 2011, the Obama administration rescinded an EPA proposal to tighten standards on ozone in the atmosphere at ground level1.   This proposal would have:

  • Lowered the maximum allowable concentration of ground-level ozone from 75 parts per billion (ppb) to 70 ppb2. This is the primary standard whose purpose is to safeguard human health.
  • Introduced a secondary standard based on a cumulative total of ozone exposure, 13 parts per million-hours (ppm-hour) in a three month period2. One ppm-hour is the exposure one receives from breathing an atmosphere of 1 ppm ozone for one hour. Two ppm-hours is the exposure of 1 ppm for 2 hours or 2 ppm for 1 hour. The purpose of the secondary standard is to protect property, quality of life, and wildlife habitat.

The question we want to consider is: Did it serve the public interest to rescind the proposed regulation or would it have been better to allow the regulation to become law? Does the benefit that the regulation provides the public outweigh the costs or vice versa?

Some might argue that a regulation that is shown to save lives offers a benefit that outweighs all costs, but that isn’t necessarily true. We put a finite price on human life all the time: insurance companies, the courts, the medical profession, governments. To show why we must do this, ask yourself this question: suppose a single person was in grave danger but could be rescued for a billion dollars. Should the government pay a billion dollars to rescue that individual? There is a raging debate how about much money to spend on medical care for the poor at a cost much less than a billion dollars per life. There are limits to how much we can spend to rescue people, especially when the costs can affect the business and economic climate3.

Another example: suppose we want to institute environmental regulation X. X will save the lives of 1000 people but will cause 10,000 people to be laid off from their jobs. Is it worth it? What if it will save the lives of 5,000 people? 10,000 people? 100,000 people? What if X will reduce tax revenues needed for schools, sanitation, police and fire services? When the question is phrased as a matter of extremes (X will save a million lives at an economic cost of ten million dollars, or X will save a handful of lives but will wreak economic havoc), most of us would find the question easy to answer. But when the costs and benefits are more balanced, that’s when it becomes tricky.

Of course, saving lives are not the only benefits of environmental regulations4. Tougher ozone standards promise to reduce the amount and severity of respiratory illness5, even to increase general wellness, helping to keep our lung function from deteriorating over long periods of time. The atheletes among us will be able to retain their abilities longer, but even ordinary people may be able to retain their vigor longer into their old age.

Lower ozone levels could particularly benefit those with pre-existing respiratory conditions, such as asthma, chronic bronchitis, and emphysema5. While people with these conditions represent just a fraction of the population, they still deserve our consideration. We have a legislative precedent: the Americans with Disabilities Act (ADA) has made life easier for millions of people6. If we demand accommodations for the blind, the deaf, and wheelchair-bound, we should also make accommodation for those with breathing difficulties.

There are also economic benefits from tougher ozone standards. If even low concentrations of ozone make some people ill, then maintaining lower concentrations will mean less illness. That means lower health care costs, less productivity lost at work, less absences at school. Ozone also damages plant life7; lower ozone levels will benefit agriculture as well as protect other forms of property (ozone is murder on certain types of rubber8). Less tangible is the damage that can be prevented to our national parks and other wildlife habitat.

On the other hands, there could be substantial costs. Ozone is not emitted directly by industry but is formed from other chemicals released into the air9. To reduce ozone, industry (as well as private cars and trucks) must curtail these emissions, and that can be expensive. If the costs are too great, companies will become less profitable, will need to cut back on hiring, will yield less tax revenue, may be tempted to move to other jurisdictions with less onerous regulation. The EPA is prohibited by law from allowing cost considerations to influence its decision to impose new and stricter regulations10. But we are not so prohibited, and we need to weigh costs against benefits to determine how society’s interests are best served.

Footnotes:

  1. Statement by the President on the Ozone National Ambient Air Qualities Standards. White House website. To view, click here.
  2. U.S. Environmental Protection Agency, National Ambient Air Quality Standards, 2010, p. 1. To view the document, click here.
  3. A related concept is the value of statistical life (VSL), which is a measure of how much people are willing to pay for reduction of danger to life. For a discussion on determining VSL in three provinces in China, see the paper The Value of Statistical Life by Jie He and Hua Wong, World Bank eLibrary, which you can view by clicking here. See also the Wikipedia article Value of Life which you can view by clicking here.
  4. For discussions of mortality associated with ozone exposure, see the U.S. Environmental Protection Agency, Integrated Science Assessment for Ozone and Related Photochemical Oxidants, Second External Draft, September 2011, Sections 2.6.2, 6.6, 7.4.10, and 7.7. To view the document, click here, then click the button “Get the Report.”
  5. For discussions of health conditions associated with ozone exposure, see the U.S. Environmental Protection Agency, Integrated Science Assessment for Ozone and Related Photochemical Oxidants, Second External Draft, September 2011, Sections 2.6, 6.2 through 6.5, and 7.3 through 7.6. To view the document, click here, then click the button “Get the Report.”
  6. For discussions of the effect of ozone on lung health, see the U.S. Environmental Protection Agency, Integrated Science Assessment for Ozone and Related Photochemical Oxidants, Second External Draft, September 2011, Sections 6.2 and 7.2. To view the document, click here, then click the button “Get the Report.”
  7. The U.S. Equal Employment Opportunity Commission maintains a website with a good summary of the ADA, which you can view by clicking here.
  8. For discussions of the effect of ozone on vegetation and the environment, see the U.S. Environmental Protection Agency, Integrated Science Assessment for Ozone and Related Photochemical Oxidants, Second External Draft, September 2011, Sections 2.7 and 9. To view the document, click here, then click the button “Get the Report.”
  9. See my post “EPA’s New Ozone Rule, Part 4” which you can view by clicking here.
  10. U.S. Environmental Protection Agency, National Ambient Air Quality Standards, 2010, p. 9. To view the document, click here.

    Actually, this prohibition is not actually stated by the Clean Air Act, but has been inferred by the courts. It is based on Section 109 of the Clean Air Act (United States Code, Title 42, Section 7409, which you can read by clicking here) which states in subsection (b)(1): “National primary ambient air quality standards…based on such criteria and allowing an adequte margin of safety, are requisite to protect the public health.” Similarly, it states in subsection (b)(2): Any national secondary ambient air quality standard…is requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air.” The Supreme Court in its ruling in the case Whitman v. American Trucking Associations, Inc. (which you can read by clicking here) inferred from the lack of mention of cost as a criteria in determining NAAQS that cost was excluded. This is because in other places, the Clean Air Act explicitly does allow cost as a criteria. As an Orthodox Jew, I take great pleasure from this argument — it could have come straight from the Talmud.

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EPA’s New Ozone Rule Part 2

Posted on December 8, 2011 | Leave a comment

Recently, the Obama administration withdrew a proposal to reduce the maximum allowable level of ground-level ozone concentration in the atmosphere1. The question that I wish to address is whether the benefits that might accrue to our nation from such a reduction are greater than the costs, particularly to industry. To analyze this problem, we need to understand what ground-level ozone is, how it is formed, what man-made processes promote ozone formation, and what industry must do to reduce the level of ozone.

Ozone is a form (called an allotrope2) of oxygen, the eighth element in the chemical periodic table3. Pure oxygen usually exists as molecules consisting of two oxygen atoms each, represented by the chemical formula O2. Ozone consists of molecules of three oxygen atoms each, represented by the chemical formula O3. Despite the fact that ozone consists of nothing but oxygen atoms, it is far more chemically reactive than ordinary oxygen4. For example, one cannot breathe pure ozone: breathing ozone in concentrations fifty parts per million or higher is probably fatal within 60 minutes5. Likewise, ozone can dissolve far more readily in water than ordinary oxygen6 and attacks substances (such as certain rubbers) that are not touched by ordinary oxygen7.

Breathing ozone is harmful to health even in low concentrations. Breathing air with 1.5 parts per million (ppm) of ozone for more than two hours can result in severe lung irritation with fluid-buildup, chest pain and cough, and extreme fatigue5. Ozone is known to attack and injure the tissues in the upper respiratory system, although the damage can be repaired by the body in a matter of weeks8.

It is important to distinguish between ozone in the troposphere (that part of the atmosphere that rests on the surface of the Earth) and the stratosphere (that layer of the atmosphere between about 6 and 31 miles above the surface at temperate latitudes). About 90% of all ozone in the atmosphere is in the stratosphere where it performs the very important function of absorbing high-energy ultraviolet radiation from the sun (all of the UV-c rays, most of the UV-b rays, and about half of the UV-a rays)9, preventing them from reaching the surface of the Earth where they would harm life. This ozone poses no dangers to humans; on the contrary, it helps make life possible. It is the 10% of the ozone in the atmosphere that exists in the troposphere (called tropospheric or ground-level ozone) that poses problems and is the subject of the proposed government regulation.

According to NASA, ground-level ozone levels without the presence of human activity should be about 10 to 15 parts per billion (ppb, one part per million equals 1000 ppb)10. Industrial activity has boosted those levels significantly such that the Environmental Protection Agency has established a limit of 80 ppb10. It appears to me that most people are able to breathe in that level of ozone without ill effects, or respiratory illnesses would be much more common than they are now. The question is whether people with respiratory problems, the very young, and the very old are adversely affected. If they are, is it cost effective to lower levels of ozone to improve their quality of life? Also, could long-term exposure to 80 ppb of ozone cause any significant health effects?

In my next post, I want to discuss how ozone is produced.

Footnotes:

  1. Statement by the President on the Ozone National Ambient Air Qualities Standards. White House website. To view, click here.
  2. For a good explanation of allotropes, see the Diffen website, Oxygen vs Ozone.
  3. See the WebElements Periodic Table on oxygen.
  4. Rachel Cassiday and Regina Frey, Washington University.Chemical Properties of Ozone. To view, click here.
  5. Ozone Levels and Their Effects, edited by Den Rasplicka, OzoneLab Instruments website. To view, click here.
  6. Bruce Mattson, Janel Michels, Stephanie Gallagos, Creighton Univerisity.Microscale Gas Chemistry, Part 28 Mini-Ozone Generator: 800 nanomoles/minute p.7 paragraph “Office Paper.” To view, click here.
  7. Bassam Z. Shakhashiri, University of Wisconsin – Madison.Chemical of the Week: Ozone paragraph 7. To view, click here.
  8. U.S. Environmental Protection Agency website, Ground-Level Ozone: Health. To view, click here. For a more detailed treatment, see Health Effects of Ozone in the General Population, which you can view by clicking here.
  9. U.S. National Aeronautics and Space Administration Ozone Hole website, Ozone Facts tab, paragraph 2. To view, click here.
  10. Jeannie Allen, The Ozone We Breathe, NASA Earth Observatory website. To view, click here.

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