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OnAir: Three Scientists Define One Elusive Phrase: “Oxidative Stress”

2009 December 22

It has been long known that air pollution causes harmful health effects in people. But scientists have only recently begun to uncover some of the mechanisms behind this causal relationship, a necessary step in understanding how to best regulate air pollution and protect human health.

One key mechanism that EPA-funded research helped identify is oxidative stress. Though it is the subject of scores of scientific papers, finding a single, comprehensible definition of the term is a surprisingly arduous task.

During an October visit to the Southern California Particle Center, I asked three scientists to define oxidative stress in the context of air pollution. Here’s what they had to say:

Arthur Cho, PhD, Organic Chemist
“As the name implies, it stresses the cell and promotes the cell to secrete chemicals that stimulate an immune response, such as symptoms of asthma. The idea is that you’re exposed to air pollutants, the pollutants enter your lungs, components of the pollutants react with components in your lungs and these potentially harmful chemical reactions are initiated.”

Ralph Delfino, MD, PhD, Epidemiologist:
“It can be thought of as a biochemical imbalance in which large molecules are oxidized to the point where they become either toxic or, in the case of important biochemicals, dysfunctional. It induces a cascade of events that leads to inflammation and, at its worst, cell death. Inflammation, as seen in immune responses to bacteria or virus, can be a good thing. But there are types of inflammation, like arthritis for example, that are not good. Oxidative stress can lead to inflammation in lungs that worsens asthma, or inflammation in blood vessels that leads to atherosclerosis.”

Andre Nel, MD, PhD, Immunologist:
“The easiest way to describe oxidative stress is to give an analogy: If you bite an apple and you hold it up in the air it will go brown after a few minutes, same with a banana. What you observe there is decay in the fruits’ tissues because oxygen radicals in the air are attacking their cell membranes. The same principle applies in humans, where oxidative stress is damage to organs and cells by oxygen radicals we are exposed to.”

Next I’ll share some surprising research I encountered at the Southern California Particle Center and report from the second leg of my tour- Harvard.

Editor’s Note: Look for more of Becky’s “On Air” posts this Science Wednesday about other EPA-funded scientists she has recently met on her travels.

About the Author: Becky Fried is a student contractor with EPA’s National Center for Environmental Research, part of the Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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6 Responses leave one →
  1. Georginius permalink
    December 22, 2009

    Pienso que es muy interesante y valorable el esfuerzo que realizan en pos de la proteccion del medio ambiente y la salud de las personas en este planeta, pero, lamentab lemente los resultados de la ultima cumbre de medio ambiente de la que participaran los lideres del mundo, no acompaño esta importantisima tarea. Saludos

  2. edgardo berraz permalink
    December 22, 2009

    It’s very important to be comprehensive about the oxidative stress,because this is the main cause of diseases,not only in lungs,also in a vary quantity of other organs.Breathing pollutig air,make to enter to general sistem,trhogouth the gaseose interchange to blood and then the particles strangers take contact with inmune cells,and this reacting producting substances that act recognizing harmful elements and treating to disipe them,but in any circunstances,this substances can be harmful per se.

  3. Michael E. Bailey permalink
    December 22, 2009

    Air pollution does have an impact on human cells and can lead to many problems. 60% to 80% of cancer causing chemicals in polluted air around major highways and industrial activities come from particles put in the air as a direct result of diesel fuel combustion. The California Air Resources Board will be doing a webinar and presenting a presentation next month that will show a link between air pollution and cardiovascular problems. Both my father and grandfather died at a young age. Both were oil well drillers. My grandfather was drilling wells in Kern County before and after WWI. My father was doing it in California, Washington State, and overseas in the 1950s. They were working before there were any emissions controls. The power for grandfather’s wells came from coal and wood and for my father’s from diesel. I can remember some early trips to drilling sites and the strong smell of oil fumes everywhere. They both died of heart problems in their 40s. They did lots of smoking and drinking, too, but the environmental factors at the early oilwell drilling sites were not in their favor. Best wishes, Michael E. Bailey.

  4. matrixneoracle permalink
    December 23, 2009

    A mon avis le phenomène de la dégradation climatique n’est pas un fait du à la production industrielle de l’homme.
    L’histoire nous enseigne qu’il y aura une fin du monde(la Bible :le soleil brûlera les hommes,et ces derniers insulteront Dieu pour cela…).

  5. markjeromy permalink
    January 8, 2010

    moderate particulate pollution kills as much as murder and abortion yet EPA director does nothing instead going after Ozone. Particulates is more damaging, coal production is more damaging. why don’t they go after polluters who produce conditions which harm people, Its not just total pollution its the consistency a population gets it? Why did the censor my other posts. Go to and go to Philly politics for my blog links. Our epa director ignores some of the most important pertintent questions about pollution and protecting people Face it people in our gov are paid off and when people are made sick jobs for the health care are more important then protecting people. These are our role models ????

  6. Springdale Clinic permalink
    February 6, 2013

    I just read about a new proof the other day that if you slice open an onion it will absorb any bacteria or viruses in the air. We obviously cannot completely clean out the air, but need to take measures to reduce oxidative stress on our bodies. Eating a good healthy diet, drinking plenty of water and making sure we get enough anti-oxidants in our daily diet is important to clear toxins. Exercise and improving circulation and oxygenation is also extremely important. And remember, it’s not only in the air but also what you eat. Many processed foods contain chemicals that can send our bodies into a tailspin. Read those labels when shopping!

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