Ozone (O3) pollution of ambient air is a significant public health problem worldwide. Emission controls on automobiles and other pollution sources have been reasonably effective in limiting the accumulation of O3 in urban areas. National Ambient Air Quality standard for O3, which is presently 0.075 ppm averaged over 8 hours. Justification for this standard derives from controlled O3 exposures of exercising human subjects with support from human epidemiology and laboratory animal toxicology.  (U.S. E. P. A. Air quality criteria for ozone and related photochemical oxidants: Integrated Science Assessment. Research Triangle Park, NC; 2013.) A new paper published by Dr Gary E. Hatch helps shed light on the effects of O3 on exercising humans.

In this Biomarker Insights paper, Biomarkers of Dose and Effect of Inhaled Ozone in Resting versus Exercising Human Subjects: Comparison with Resting Rats, new research is presented to explore the influence of exercise on pulmonary dose of inhaled pollutants. This study discusses the influence of physical exercise in humans on the resultant alveolar dose and effect of inhaled O3. Author Dr Gary E. Hatch explains the background and results of their study.

How did you become interested in studying the dose and effects of inhaled ozone in resting and exercising humans? 

My work for the U.S. Environmental Protection Agency exposed me to the widespread prevalence of ozone air pollution and to the expensive emission controls on automobiles that are intended to regulate ozone pollution.  Ozone regulations depend on an extensive literature obtained from both human and animal inhalation toxicology studies.  We initially sought to more effectively extrapolate effects observed in animals to humans and used oxygen-18 labeling to track the reaction of ozone in animal and human lungs.  What we found initially was that rat lungs received a lower than expected dose of ozone compared to humans.  This study found a major reason why: rats were not exercising and humans were.

What was previously known about the effects of inhaled ozone/pollutants in exercising and resting humans?  How has your work in this area advanced understanding of it?

Previous to this paper, numerous studies of exercising humans and of resting rats were published and most assumed that rats would be more sensitive to ozone than humans.  This paper was one of the first to measure dose and effects in resting humans.  When we did this, we found that resting rats and resting humans had the same pulmonary alveolar dose of ozone.  

What do regard as being the most important aspect of the results of your research?

The ozone dose and effect comparison between rest and exercise in humans, and between resting humans and laboratory rats is significant because they tie together human and rat studies.  They also give an appreciation for the large role that physical exercise plays in determining the alveolar dose of ozone.  These findings probably extend to other chemically reactive air pollutants.

What was the greatest difficulty you encountered in studying the dose and effect of inhaled ozone in resting and exercising humans?

Making the numerous measurements in appropriately exposed human subjects was a challenge for all authors on the study.  All of the techniques were difficult to perfect and required team efforts.  The oxygen-18 labeling of ozone and the detection of excess oxygen-18 in biological tissues has taken years to perfect.  

The paper Biomarkers of Dose and Effect of Inhaled Ozone in Resting versus Exercising Human Subjects: Comparison with Resting Rats is freely available to download, comment on, and share.

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