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Asthma in Children: Effects of Exposure to Diesel Exhaust Particles
Oct12

Asthma in Children: Effects of Exposure to Diesel Exhaust Particles

By The Editors Diesel exhaust particles are one of the major components of air pollution. These particles are suspended in the air, and are microscopic — less than one-fifth the thickness of a human hair. As we breathe, they are drawn deep into the lungs. Because diesel-powered engines are everywhere, it is almost impossible to avoid them. People that live and work in urban and industrial areas are more likely to be exposed. Combined results from many epidemiological, clinical, and toxicological studies show that diesel exhaust particles are associated with respiratory disorders, as for example severe asthma. It is not surprising that children are especially susceptible to the effects of these particles. Results form a recenty study entitled “Diesel exhaust particle induction of IL-17A contributes to severe asthma” and published onine (September 23, 2013) in the Journal of Allergy and Clinical Immunology,  show that exposure to diesel exhaust particles from traffic pollution leads to increased asthma severity in children. The study was conducted by researchers at Cincinnati Children’s Hospital Medical Center. and provides insight into the mechanisms responsible for the development of severe asthma in children exposed to high levels of diesel exhaust particles — these mechanisms involve expansion of a type of white blood cells called T helper 17 cells and increased production by these cells of a protein, IL-17A. This protein is known to be associated with several chronic inflammatory diseases, including rheumatoid arthritis, psoriasis and multiple sclerosis. The researchers studied 235 children and teens with asthma by estimating their diesel exposure attributable to traffic based on where they lived. The researchers also studied mice exposed to diesel particles and dust mites, a common household allergen. In children with asthma, diesel exposure was associated with more frequent asthma symptoms and increased IL-17A blood levels. In mice, exposure to diesel and dust mites resulted in more severe asthma when compared to dust mite exposure alone. Neutralization of IL-17A in mice resulted in alleviation of airway inflammation induced by diesel exposure. Gurjit Khurana Hershey, MD, PhD, director of asthma research at Cincinnati Children’s and senior author of the study says that neutralization of IL-17A “may be a useful potential therapeutic strategy to counteract the asthma-promoting effects of traffic-related air pollution, especially in highly exposed, severe allergic...

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Ozone, Plants and Heat Waves: Team Players in Adverse Health Effects
Jul23

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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