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Ozone, Plants and Heat Waves: Team Players in Adverse Health Effects

Ozone, Plants and Heat Waves: Team Players in Adverse Health Effects

By The Editors Ozone, the principal component of the mixture of air pollutants known as “smog“, is produced from the action of sunlight on air contaminants from automobile exhausts and other sources. According to the U.S. Environmental Protection Agency (EPA) “Ozone in the air we breathe can harm our health—typically on hot, sunny days when ozone can reach unhealthy levels. Even relatively low levels of ozone can cause health effects. Breathing ozone can trigger a variety of health problems including 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 Effects on the Airways.  Ozone is a powerful oxidant that can irritate the air ways causing coughing, a burning sensation, wheezing and shortness of breath and it can aggravate asthma and other lung diseases.           In the Summer, strong sunlight and hot weather result in harmful ozone concentrations in the air we breathe. Ozone can be transported long distances by wind.  For this reason, even rural areas can experience high ozone levels.  And, in some cases, ozone can occur throughout the year in some southern and mountain regions. Plants can reduce ozone concentrations. However, in presence of heat waves, they become stressed and stop absorbing ozone and other pollutants. Results from a new study, set to quantify the impact of increased ozone levels on human life, show that this phenomenon led to about 406 premature deaths in the UK during the 2006 Summer heat wave. All estimated premature deaths were in addition to human health and mortality impacts from the heat itself. The study, entitled “Scorched Earth: How will changes in the strength of the vegetation sink to ozone deposition affect human health and ecosystems?” was published a few days ago (July 18) in the scientific journal Atmospheric Chemistry and Physics.   Dr. Lisa Emberson, lead author of the study, explains that “Vegetation can absorb as much as 20 per cent of the global atmospheric ozone production, so the potential impact on air quality is substantial. During heat waves – when the ground is especially dry – plants become stressed and shut their stomata (small pores on their leaves) to conserve water. This natural protective mechanism makes them more resilient to extreme heat and high ozone levels, but it also stops them from absorbing ozone and other pollutants.” The extent of the problem depends on how dry the soil is, since it is the combination of heat and drought that stresses plants the most. Dr. Emberson says the study...

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