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EPA proposes tightening primary ozone standards to range of 65-70 ppb; final rule by October 2015

Counties where measured ozone is above proposed range of standards, based on 2011-2013 monitoring data. Source: EPA. Click to enlarge.

The US Environmental Protection Agency (EPA) is proposing tightening the ground-level 8-hour ozone (O3) National Ambient Air Quality Standards (NAAQS) to within a range of 65 to 70 parts per billion (ppb), while taking comments on a level as low as 60 ppb. Earlier this year, EPA staff had recommended the further reduction of this primary ozone standard from the current 75 ppb (parts per billion) to a revised level within the range of 70 ppb to 60 ppb—and preferably below 70 ppb. (Earlier post.)

EPA will seek public comment on the proposal for 90 days following publication in the Federal Register, and the agency plans to hold three public hearings. EPA will issue final ozone standards by 1 October 2015.

The Clean Air Act established two types of national air quality standards:

  • Primary standards set limits to protect public health, including the health of at-risk populations such as people with pre-existing heart or lung disease (such as asthmatics), children, and older adults.

  • Secondary standards set limits to protect public welfare, including protection against visibility impairment, damage to animals, crops, vegetation, and buildings.

The Clean Air Act requires EPA to review the standards every five years by following a set of open, transparent steps and considering the advice of a panel of independent experts. EPA last updated these standards in 2008, setting them at 75 ppb.

EPA scientists examined numerous scientific studies in its most recent review of the ozone standards, including more than 1,000 new studies published since the last update. Studies indicate that exposure to ozone at levels below 75 ppb—the level of the current standard—can still pose serious threats to public health, harm the respiratory system, cause or aggravate asthma and other lung diseases, and is linked to premature death from respiratory and cardiovascular causes.

Ground-level ozone forms in the atmosphere when emissions of nitrogen oxides and volatile organic compounds “cook” in the sun from sources such as cars, trucks, buses, industries, power plants and certain fumes from fuels, solvents and paints. People most at risk from breathing air containing ozone include people with asthma, children, older adults, and those who are active or work outside. Stronger ozone standards will also provide an added measure of protection for low income and minority families who are more likely to suffer from asthma or to live in communities that are overburdened by pollution. Nationally, 1 in 10 children has been diagnosed with asthma.

According to EPA’s analysis, strengthening the standard to a range of 65 to 70 ppb will provide significantly better protection for children, preventing from 320,000 to 960,000 asthma attacks and from 330,000 to 1 million missed school days. Strengthening the standard to a range of 70 to 65 ppb would better protect both children and adults by preventing more than 750 to 4,300 premature deaths; 1,400 to 4,300 asthma-related emergency room visits; and 65,000 to 180,000 missed workdays.

Costs are estimated at $3.9 billion in 2025 at a standard of 70 ppb, and $15 billion at a standard at 65 ppb nationwide, excluding California. EPA has analyzed costs and benefits for California separately, because a number of California counties would have longer to meet the proposed standard, based on their ozone levels. A number of California counties likely would have attainment dates ranging from 2032 to late 2037.

Estimated costs of meeting the proposed standards in California post-2025 are $800 million for a standard of 70 ppb, and $1.6 billion for a standard of 65 ppb.

EPA estimates gained health benefits of $6.4 to $13 billion annually for a standard of 70 ppb, and $19 to $38 billion annually for a standard of 65 ppb, except for California, factoring in an estimated:

  • 750 to 4,300 premature deaths;
  • 790 to 2,300 cases of acute bronchitis in children;
  • 1,400 to 4,300 asthma-related emergency room visits;
  • 320,000 to 960,000 asthma attacks in children;
  • 65,000 to 180,000 days when people miss work; and
  • 330,000 to 1 million days when children miss school.

Benefits of meeting the proposed standards in California add to the nationwide benefits after 2025, with the value of the additional benefits ranging from an estimated $1.1 to $2 billion at a standard of 70 ppb to $2.2 to $4.1 billion for a standard of 65 ppb.

A combination of recently finalized or proposed air pollution rules—including “the Tier 3 clean vehicle and fuels standards (earlier post)—will cut smog-forming emissions from industry and transportation, helping states meet the proposed standards, EPA suggested.

EPA’s analysis of federal programs that reduce air pollution from fuels, vehicles and engines of all sizes, power plants and other industries shows that the vast majority of US counties with monitors would meet the more protective standards by 2025 just with the rules and programs now in place or underway. Local communities, states, and the federal government have made substantial progress in reducing ground-level ozone. Nationally, from 1980 to 2013, average ozone levels have fallen 33%. EPA projects that this progress will continue.

The Clean Air Act provides states with time to meet the standards. Depending on the severity of their ozone problem, areas would have between 2020 and 2037 to meet the standards. To ensure that people are alerted when ozone reaches unhealthy levels, EPA is proposing to extend the ozone monitoring season for 33 states.

Secondary standard. EPA is proposing to define the secondary standard in terms of a “W126 index” in a range of 13 to 17 parts per million-hours (ppm-hours), averaged over three years. A “W126 index,” named for the formula used to calculate it, is a seasonal index often used to assess the impact of ozone on ecosystems and vegetation.

To achieve a level of protection equivalent to 13 to 17 ppm-hours based on the W126 metric, EPA is proposing to set an 8-hour secondary standard at a level within the range of 65 to 70 ppb. EPA analyzed data from air quality monitors and found that setting a standard in a W126 form would not provide additional protection beyond an 8-hour standard.

EPAis seeking comment on setting the standard based on the W126 metric within a range of 13 to 17 ppm-hours, averaged over three years. EPA also is seeking comment on defining a target protection level in terms of a W126 index value as low as 7 to 13 ppm-hours. In addition, EPA is taking comment on retaining the existing 8-hour secondary standard.




Another example how we have knowingly made many of our children sick and kill many for years.

There are a few hundreds-thousands other similar examples?


Once again the EPA Bureaucrats have to protect their jobs, because the country has cleaned up, and satisfied their regulations.

So plant/fund, a couple of pre-ordained studies that question the present standard.

Then move the goalposts.

We are already tighter than what naturally occurs after a Thunderstorm. When the air is washed clean, and smells fresh from the Ozone created by the thunder and lightning.

That is supposedly bad and unhealthy for you. What Utter bilge and drivel.



The EPA has known for a long time that ozone is a problem. In fact, ozone has been it's primary focus on decreasing up until now. The problem is how do you regulate something so that it provides a meaningful improvement on quality of life and befit while at the same time making it feasible to obtain. Much of the decrease in ozone has come from regulating NOx emissions from power plants and other sources, however, ozone chemistry is much more complex than just NOx. It's production requires a balance of NOx and VOCs and it is a highly non-linear process.


That isn't quite true. Although, lightning does produce ozone much of it occurs further into the atmosphere than at the surface (remember that the EPA doesn't set regulation other than at the surface). Background concentrations of ozone (meaning average values away from sources) are about 30 ppbv which is well below the amount they are trying to regulate. They cannot regulate much lower than this because it would become infeasible for states like Maryland for instance to obtain.

It is a well known fact that ozone, and some of it's precursors at high concentrations found in some areas are not healthy not just for humans but for the environment as well.

Much of the planning and regulation is highly dependent on 3d chemical transport models. There are large unknowns and known errors within the transport, dynamics, chemical and other processes within these models. Although, many improvements have been seen in the past 10 years in these models.


D, one more thing. Days in which there are high levels of ozone typically come during warm, clear skies, and under a high pressure system. These conditions are not usually where lighting and thunderstorms exist. Frontal systems can cause an exceeedance in ozone but it is typically due to transport not from lightning



Quoting an "average" of 30pbbv Ozone level is pure prevarication.

It doesn't thunder and lightening every day in the USA. Averaging rainy days together with no precipitation days, to produce an average of 30 pbbv is utter nonsense.

What is the natural background ozone level during and right after a thunderstorm?

Now the EPA is giving the desert Southwest a hard time about dust storms. These natural events put too many particles in the Air, so the Air Quality falls due to excessive PM10, and PM2.5.

Another example of EPA drivel, or perhaps the EPA remedy is to pave the deserts.

The reality is that the USA has effectively met all the definitions for Clean Air set by the EPA back in the 1970s, when the Air Quality was unsatisfactory. Now those definitions/regulations have been met, for all but a half a dozen or so, of the 2500 counties in the USA.

Even those accidents of geography like the LA Basin, withits air inversions, are much cleaner than before, and are probably cleaner than when the only inhabitants of "the Valley of Smokes" were American Indians.

As Air Quality Compliance was achieved, we haven't declared Victory. The EPA, fearing no job justification and RIFs, has been moving the goalposts targets ever tighter.

It is well past time to declare Victory and hold a National Celebration. Then we can refocus our national resources to other urgent unmet needs.



Our understanding of the health, economic and environmental impact that air quality has is significantly more than when the regulations were first set in the 70s. To quote that and declare air quality a victory is ridiculous. Further improvement of air quality will only benefit everyone.

Much of the understanding of dust storms and the emissions from it is not well understood. Further investigation is needed and is actively being pursued. I'll point you to Tong et al. as an example.

I was quoting an average of 30 ppbv based on several years in computational physics with 3d chemical transport models. Although, this is an estimated value it is typical concentrations that you would see in remote rural areas without a lot of industry. Take a look at the EPA AQS data sometime and check it out for yourself. Nitrogen dioxide (which is what you are saying the main cause from lightning) is formed naturally in the atmosphere by lightning and some is produced by plants, soil and water. Ozone is produced naturally and is transported from other regions (i.e. long range transport, stratosphere troposphere exchange, etc.) and it's chemistry is a delicate balance between volatile organic compounds and nitrogen dioxides. The book by Seinfeld and Pandis is sort of a bible for this stuff and is a decent read on the subject.

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