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'Bad' Ozone Threatens Human and Plant Health
Cumulus clouds obscured by pollution
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The effects of 'bad' ozone and other contaminants on Earth's atmosphere are evident in this photograph of cumulus clouds obscured by pollution. Credit: NASA/Mark Schoeberl

Jack Fishman

Jack Fishman. Credit: NASA/Sean Smith

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› About 'Bad' Ozone

Ozone in the Earth's lower atmosphere, or troposphere, has increased significantly in the last 100 years, with harmful effects on humans, plants and animals. Exposure to increased ozone levels can cause throat and lung irritation or aggravation of asthma or emphysema.

This so-called "bad" ozone forms when nitrogen oxide gases from vehicle and industrial emissions react with volatile organic compounds -- carbon-containing chemicals that evaporate easily into the air, such as gasoline and paint thinners.

On Wednesday, August 25, senior research scientist Dr. Jack Fishman at NASA's Langley Research Center will answer your questions about ozone. Joining the chat is easy. Simply visit this page on Wednesday, August 25, from 1 to 2 p.m. EDT. The chat window will open at the bottom of this page starting at 12:30 p.m. EDT. You can log in and be ready to ask questions at 1 p.m..

See you in chat!

More About Chat Expert Jack Fishman

Fishman, a NASA Langley employee since 1979, is an expert in the composition of the troposphere, for which he has developed numerical models that provide insight into the processes controlling the chemistry in the atmosphere. In addition, Fishman developed unique capabilities for use of satellite and other remotely sensed measurements to study the composition of the troposphere.

He is a native of St. Louis, Mo., and holds a Bachelor of Arts degree in mathematics from the University of Missouri, and a Master of Science degree and Ph.D. in meteorology from Saint Louis University.

Patrick(P) This is NASA Langley. Thanks for joining the chat today. Jack is with us and busy answering his first question.
Akarsh_Valsan(Q) How is ozone produced?
Jack(A) There are two main processes. In the stratosphere very intense ultraviolet radiation breaks apart the oxygen atom [molecule] and through a series of reactions, ozone is formed when the atomic oxygen recombines with the molecular oxygen. In the troposphere, the process is more complicated. We need precursor pollutants, primarily nitrogen oxides and hydrocarbons, and through a series of reactions initiated with sunlight, ozone is formed.
Jason(P) Hi everyone. Welcome to today's chat. To submit your own question to Jack, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.
Patrick(P) Abishek.N -- your question is up next!
Abishek.N(Q) Hi will deplition of ozone have any affect in photosynthesis process
Jack(A) It will have some effect, but relatively minor, our studies show.
Akarsh_Valsan(Q) Which are the diseases caused by ozone depletion?
Jack(A) Ozone depletion in the stratosphere will allow more ultraviolet radiation to reach Earth's surface. This in turn will result in the formation of more skin cancer and cataracts.
Akarsh_Valsan(Q) What is the role of CFC's in depletion of ozone layer?
Jack(A) CFCs, or chlorofluorocarbons, are inert molecules in the lower atmosphere. The only place they can be destroyed is when they reach the upper stratosphere, where the intense sunlight will break them apart and release their chlorine atoms. For every chlorine atom released, between 10,000 and 100,000 molecules of ozone are destroyed.
Abishek.N(Q) how long will it take for us to regain our lost ones
Jack(A) The CFCs released at the surface take about 20 years to reach the stratosphere before they are broken apart by sunlight. Now that there is a treaty in place to stop the release of CFCs, it is estimated that recovery will take on the order of 50 to 100 years.
John_doe(Q) How does the ozone affect things like acid rain?
Jack(A) There are no direct effects. But more ozone in the lower atmosphere will speed up the conversion of sulphur dioxide and nitrogen dioxide to form acids.
Jason(P) We're working to get through all of the great questions you've asked us. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.
John_doe(Q) Is global warming a factor in the increasing bad ozone??
Jack(A) It's a complex question with no definitive answer. However, increased ozone in the troposphere will have an effect on global warming. As far as trace gases go, it may be only second to warming from carbon dioxide.
Patrick(P) NASA Langley here -- Fertilizer info... comin' up! ...really.
Akarsh_Valsan(Q) l nitrous oxide present in fertilizers destroy ozone layer?
Jack(A) Again, this is a complex question. The nitrous oxide will eventually drift to the stratosphere. Theoretical models are dependent on exactly where in the stratosphere this reaction takes place. At one time it was thought that fertilizer emissions would be a major impact on the ozone layer, but now the thinking is that the effect is probably small.
DCollins52(Q) why is some ozone considered "bad" in some places? its made out of just 3 oxygen molecules, while 2 molecules are fine......
Jack(A) Actually, it's 3 oxygen atoms and readily gives up that extra oxygen atom to become the much more stable oxygen model [molecule]. In this respect ozone is a very strong oxidant. Oxidants in general destroy [react with the complex molecules that comprise] living things, including plants and tissues such as that found in the lungs.
Dell_Conagher(Q) How can you differtiate between damage to crops from ozone compared to other environmental factors?
Jack(A) There's been a lot of research done on these effects. We know that certain plants are more susceptible and the experts in the field have learned to recognize the symptoms of damage caused by ozone rather than other diseases or heat stress.
john(Q) which part of world have major problem with ozone deplection?
Jack(A) Ozone depletion occurs primarily near the poles. The most sensitive groups are people living in Scandanavian countries and also the population in New Zealand is very aware of ozone depletion.
carolinad28(Q) can gaps on the ozone layer be seen from space over countries where polution is a major issue (such as China)?
Jack(A) Ozone pollution can be seen from space and there are certainly large and increasing amounts over China. Other areas include the eastern U.S. and southern California.
John_doe(Q) How did you get to work for NASA? Any tips for the rest of us?
Jack(A) I was fortunate enough to get a degree in atmospheric chemistry, which was an area NASA was very heavily involved in researchwise. I happened to be in the right place at the right time in 1979.
Akarsh_Valsan(Q) Do Bromine and Halocarbons destroy Ozone layer?
Jack(A) Bromine, like chlorine, is a very efficient destroyer of ozone. However, there's not as much bromine in the atmosphere as chlorine, so the destruction of the ozone layer by bromine is less.
shiftypowers(Q) Does ozone depletion pose any danger to aquatic plant life?
Jack(A) It's generally believed that increased ultraviolet radiation will do damage to the phytoplankton, which are fundamental food for small aquatic animals.
Abishek.N(Q) Wat is the colour of ozone molecules.
Jack(A) Ozone is basically colorless but in very high concentrations it has a bluish tinge to it.
John_doe(Q) How do you 'see' ozone from space?
Jack(A) NASA has been flying satellites since the mid 1970s that have instruments that can measure ozone. Since that time, there have been about a dozen different satellites that have been measuring ozone so that we can observe trends and where depletion of the ozone layer is most pronounced.
isokudoku(Q) Are there anything left for us to make it better in daily life?
Jack(A) It's the old saying, 'think globally, act locally.' If everyone is conscientious about reducing emissions from fossil fuels, the precursors for ozone will be reduced and less ozone will be formed in the troposphere.
John_doe(Q) Thanks for the 'see'-ing answer about satellites, but how do you do it from them? Do you take pictures? Beam lasers? What?
Jack(A) The technique is called differential absorption. What this means is that there are specific wavelengths where only ozone absorbs ultraviolet radiation. What the satellites actually measure is the radiation coming back from those wavelengths. Using that information, we can determine how much ozone is actually present.
Abishek.N(Q) What can we contribute as students for this?
Jack(A) There is a program called GLOBE (Global Learning Through Observations To Better The Environment), which has developed a relatively inexpensive instrument to measure ozone. These measurements can be entered through their web site and students can look at data taken around the world so that they can tell where ozone pollution is.
Jason(P) We're working to get through all of the great questions you've asked us. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.
Akarsh_Valsan(Q) Why are holes formed in ozone layer?
Jack(A) Holes are formed at both the north and south poles, with the south pole ozone hole being much more intense. The reason for this is that's where the coldest temperatures are found, and this results in the chlorine atoms being concentrated at this region. This results in the appearance of a hole because of the very low concentrations -- 90 percent of the ozone [at some altitudes] in the stratosphere -- is removed during parts of the year.
Joel(Q) It seems years ago there was a more distinct public fear of the ozone depleting, but now it seems it is not so much in the public conscience. Do you agree with this, and what would you say to people who may not know that this is a problem? Why is this a pressing concern.
Jack(A) The world got together and formed a treaty to stop producing CFCs. As a result, we're in the process of solving the problem, but it will take time. In addition, however, global warming in the lower atmosphere has resulted in global cooling in the stratosphere and the reactions that would replenish ozone are occuring slower than they did several decades ago.
John_doe(Q) In terms of academics to get where you were, you mentioned atmospheric chemistry. What foundation courses did you take before you specialized like that?
Jack(A) My undergraduate degree was in mathematics, with a minor in chemistry. So I recommend both chemistry and math courses. In graduate school, my degree is in meteorology, which required physics and meteorology courses.
JacksBrother(Q) What areas of the Earth have the highest non-urban ozone concentration?
Jack(A) When we first started to measure ozone in the lower atmosphere, we found some of the highest concentrations out in the middle of the South Atlantic Ocean. As it turned out, this was a result of intense biomass burning in both southern Africa and South America. Because of the meteorology in the region, the South African pollution was caught in the Easterlies, and the South American pollution was transported higher in the atmosphere in the Westerlies. As a result, they met right in the middle, and the highest concentrations were found in a region we did not expect to find them before we had the satellite measurements.
Jason(P) We're still working on answering all the questions you've asked. If you haven't seen yours yet, give us a few minutes to get to all of your questions. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.
Abishek.N(Q) how can cfc be controlled
Jack(A) CFCs have been replaced by other chemicals that don't release chlorine into the stratosphere.
jdcollings(Q) Is there a way that geoengineering could solve problems of too much ozone in the troposphere, and not enough in the stratosphere?
Jack(A) Several techniques have been proposed. In reality, however, all of these would be very expensive and not practical.
Patrick(P) We've got a little less than 15 minutes left. If your question wasn't answered, check back with us to see a full transcript of this chat session in 2 to 4 days. It's possible that your question was answered earlier in the chat.
jdcollings(Q) Do forest fires release harmful gases into the atmopshere that affect ozone?
Jack(A) Any form of combustion releases trace gases that can become ozone. The amount of forest burning in any given year is dependent on the local climatic conditions. So the relative impact of the fire emissions is that is a substantial fraction of the fossil fuel emissions.
JacksBrother(Q) Which cities have the highest ozone concentations, averaged over the year?
Jack(A) In general southern and central California has the highest ozone concentrations.
mcolonro(Q) Is there any way to discriminate between NOx-limited or carbon-limited ozone from space?
Jack(A) That's a real good question. Right now, the answer is no, but we are hoping the future to have satellites to help answer this question by increasing both spatial and temporal resolution of the measurements.
Patrick(P) Under 10 minutes left. If you've got something you really want to know, start typing now.
Dell_Conagher(Q) How did you become interested in tropospheric ozone?
Jack(A) I've always been interested in air pollution, and it seemed like understanding the origin of ozone was one of the most challenging problems. In the 1970s, EPA was formed to curtail air pollution and I wanted to be part of that movement.
Patrick(P) 5 minutes left!
Rory(Q) how much damage has been to done to crops in the UYS?
Jack(A) We just completed a study that estimated that up to 10 percent of the soybean crop was destroyed by ozone in the past decade in the U.S. The value of the crop is $25 billion per year, so the cost to the U.S. soybean farmers was on the order of $2 billion a year. Global estimates, taking account of all crops, range between $14 and $26 billion per year.
Jason(P) Thank you for attending today's web chat with senior research scientist Dr. Jack Fishman at NASA's Langley Research Center. And a big thanks to Jack for taking time out of his day to answer all your questions. A transcript of this chat will be posted to this web page within 3-5 business days. Thanks!