Howie Garber – March 2010

Surface-level or ground level ozone (O3) is one of 7 major air pollutants regulated by the EPA under the U.S. Clean Air Act. These include carbon monoxide, lead, nitrogen dioxide, pm-10, pm 2.5, ozone, and sulfur dioxide.

“Good ozone” occurs naturally in the stratosphere approximately 10 to 30 miles above the earth’s surface and forms a layer that protects life on earth from the sun’s harmful rays.

From Utah Daq website :Bad Ozone is formed when hydrocarbons (also known as volatile organic compounds, or VOC) and nitrogen oxides (NOx) chemically react in the presence of sunlight and heat. Hydrocarbons are emitted from automobiles, gasoline stations, paint, cleaning fluids, and many other sources. Plants also give off some reactive hydrocarbons, such as terpenes from pine trees. Nitrogen oxides are emitted by automobiles, power plants, and other combustion processes.

Ozone production is a year-round phenomenon. However, the highest ozone levels occur during the summer when strong sunlight, high temperatures, and stagnant meteorological conditions combine to drive the chemical reactions and trap the air in the region for several days. Ozone produced under these conditions can then be transported many miles outside the urban formation area.

This fact accounts for much of political controversy. Ozone is also produced by forest fires and it is thought that much of Wasatch front ozone comes from So California. According to Dr Moench who is the founder of UPHE, ozone in Canyonlands N.P. in 07 was similar to ozone along Wasatch front. Ozone is being monitored at Canyonlands, Mesa Verde, Grand Canyon andYellowstone.

Health effects

Breathing ozone can trigger a variety of health problems including death, chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground-level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

Ozone affects everyone not just susceptible individuals . In one study 25 % of individuals had >10% decrease in lung function (FEV1)at 0.08ppm, which is just higher than the epa standard of .075ppm

From  a study in circulation short-termO3 exposure within a period of 1 to 2 days was related to acutecoronary events in middle-aged adults without heart disease,whereas NO2 and SO2 are not.

From Jama A 10-ppb increase in the previous week’sozone was associated with a a 0.64% increasein cardiovascular and respiratory mortality. Study concluded  a statistically significantassociation between short-term changes in ozone and mortalityfor 95 largeUS urban communities, which includeabout 40% of the totalUS population.

The long term impact of ozone was further revealed by a study published in March, 2009

of 450,000 adults tracked over 18 years that demonstrated an increase in respiratory caused deaths rates due to ozone and a three-fold increase in the rate of respiratory death in cities where ozone levels are the highest 3.  –March 09 NeJm

Air pollution may have its largest impact on public health through its affect on the human embryo.   Exposure of pregnant women to ozone at levels well below NAAQS results in intrauterine growth retardation26 including smaller head size, increased rates of spontaneous abortions, premature births and low birth weight syndrome.

The CDC reported that during the 1996 Summer Olympics Games inAtlanta, morning traffic decreased 23% and peak ozone levels decreased 28%, emergency visits for asthma events in children decreased 42%. At the same time, children’s emergency room visits for causes other than asthma did not change. These results suggest that efforts to reduce traffic congestion and improve air quality can also help improve the respiratory health of a community.

The association between ozone exposure, poor lung function and reduced life expectancy is strong and well established.

Because ozone increases with daytime heating, it is important to check ozone levels before exercising on hot days and exercise early in the day during the summer.

So you are probably getting the message that short or long term exposure to ozone can unhealthy or even deadly.

I want to compare what we know about ozone with our knowledge of small particulate air pollution which is the major health problem during our winter inversions. The small particulates are a much greater problem than ozone.

Fine particles have been linked to effects such as: cardiac arrhythmias; heart attacks;  strokes, pneumonia, asthma attacks; lung cancer and bronchitis. These effects result in increased hospital admissions, emergency room visits,  and absences from school or work.

To provide some background: the EPA announced in Dec 08 thatSaltLakeCountywas a non attainment area for PM2.5. This was because the average yearly Pm2.5 concentration inSaltLakeCountyexceeded 15ug/m3.Utahred alert days corresponds to the EPA standard of and we have 15 to 35 of these days every year. A recent study on the Wasatch Front conducted over 8 years showed that days with PM2.5 increases of 10ug/m3 resulted in an increase in heart attacks and strokes of 4.5%. The results were linear so that on a smoggy day with a level of Pm2.5 of 60 would have a 25% increase in heart attacks.  With regard to long term PM2.5 exposure, a recent national study of 65,000 women conducted over 4 years found that a 10ug/m3 rise in chronic PM2.5 exposure resulted in a 24%increase in the risk of cardiovascular events, a 76% increase in the risk of death from heart disease, and a 35% increase in the risk from stroke. Particulate air pollution has been shown to accelerate atherosclerosis and inflammation throughout the body..

Current estimates are that along the Wasatch front, 1000 to 2,000 people die each year from the direct effects of air pollution. It is important to note that no level of ozone or particulate air pollution is safe and the limits that the EPA sets are constrained by politics, the demands of industry, and our needs to drive and burn fossil fuels.

Now that you have heard all of the bad stuff, I wanted to share some good news. In a 2009 study Dr Arden Pope looked at fine particulate air pollution in 50 cities across the U.S. starting in the late 1970s and comparing this with the late 1990sinto early 2000. Particulate air pollution improved in all 50 cities and this resulted in as much as one year improved life expectancy. To be more specific , A reduction of 10 μg per cubic meter in PM2.5 was associated with an increased life expectancy of one year for the least-polluted areas and 0.57±0.26 year for other areas;

The average reduction in the PM2.5 concentration  was 6.52 μg per cubic meter in the fifty metropolitan areas included in the study. The average increase in life expectancy attributable to the reduced levels of air pollution was approximately 0.4 years. In metropolitan areas where reductions in PM2.5 were 13 to 14 μg per cubic meter, increases in life expectancy may have been as much as 0.82 years. This improved air quality was very much related to the widespread use of catalytic converters in automobiles which could be used on a widespread basis when they took the lead out of gasoline. For 1980 to 2000, the average increase in life expectancy was 2.72 years for the counties in this analysis.

Ozone effects on plants from Nasa

Because ozone formation requires sunlight, periods of high ozone concentration coincide with the growing season. Just as in damage to people, ozone damage to plants can occur without any visible signs. Physiologists know that some cell membranes become leaky, possibly because of ozone’s ability to interact with lipid (fatty) components and/or membrane proteins. Photosynthesis slows, resulting in slower plant growth. Ozone causes a decrease  in the numbers of flowers and fruits a plant will produce, and impairs water transport. Plants weakened by ozone may be more susceptible to pests, disease, and drought.

Studies of soybean yield at the University of Maryland found a 10 percent loss of soybean crop due to current levels of ozone in that state, which are commonly 40-80 ppb during the growing season, with particular episodes much higher. The same study showed that ozone exposure causes the loss of 6-8 percent of winter wheat and 5 percent of the corn crop yields toMarylandfarmers. High ozone concentrations can affect not only plant growth, but soil fertility. Ozone pollution also harms forests and prolonged exposure has serious consequences

On March 12, 2008, the EPA tightened the 8-hour standard to 0.075 ppm.  This action has placed severalUtahcounties located along the Wasatch Front in jeopardy of being designated nonattainment.

The politics of the 2008 decision was quite controversial . The  Bush Epa essentially ignored the recommendations of the Clean Air Scientific Advisory Committee  which  recommended  a range of 0.070 to 0.060 ppm.

The EPA is now poised to lower the ozone standard consistent with what was recommended in 2008. They are proposing a primary 8 hour standard  within the range of 0.060 to 0.070 ppm. The EPA is proposing a major change in the secondary standard which will be computed over three months and is a complicated weighted average. This is designed to provide  increased protection against O3-related adverse impacts on vegetation and forested ecosystems.


Written on December 17th, 2011

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