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Seniors and Asthma
Effects of ozone pollution on seniors Seniors, as well as children, are particularly susceptible to the effects of ozone pollution. Those with asthma and rhinitis seem to be more sensitive to pollutants. Epidemiologic studies have shown increased emergency hospital admissions for acute asthma, as well as need for medications such as albuterol. In addition to allergen triggers, environmental exposures to air pollution contribute to increased morbidity. Even short-term exposure to ozone can increase bronchial allergen responsiveness in both seniors and children with mild allergic asthma. Ozone exposures have been associated with poorly controlled asthma in elderly adults. Ozone is a secondary pollutant, which is formed by the interaction of oxides of nitrogen, volatile organic compounds with ultraviolet light. The main sources of these oxides are automobiles and petroleum-driven engines. Studies performed in both animals and humans have shown that many pollutants can cause airway inflammation. There is a link between the upper and lower airway. A recent study on the effect of ozone on the nasal mucosa in nasal biopsies taken 6h after exposure to either 400 ppb ozone demonstrated that that ozone significantly increases the number of neutrophils in the epithelium, the expression of NF-kB , TNF-a IL-1b, IL-8 IL-6, GM-CSF and ICAM-1 in the nasal epithelial cells, suggesting that ozone-induced inflammation of the nasal mucosa may be a consequence of increased synthesis and release of epithelial cell-derived cytokines and adhesion molecules which influence the activity of inflammatory cells. Genetics and gene expression in the presence of allergens, ozone, viruses and other oxidant injury can lead to airway inflammation. Culture studies of epithelial cells have shown ozone and other particles can lead to increased inflammatory proteins called cytokines or Interleukins (IL). Studies on the effects of ozone on inflammation related to IL-6 and IL-8 in lung fluid from nonsmokers and asthmatics found that the subtle effects of ozone exposure may persist for three weeks in some subjects. A recent human study reported an association of TNFa genetic polymorphisms and ozone-induced changes in lung function. Other effects of ozone on the airways that have been reported include acute bronchoconstriction, hyperreactivity, dysfunction of the epithelium and hyperpermeabilty. Ozone can also cause an immediate drop in lung function or forced vital capacity (FVC). Therefore, asthma patients should avoid exertion or exercise outside to the extent possible when levels of air pollution are high. Studies have found that hikers with asthma or a history of wheeze had a four-fold greater response to ozone than others and with prolonged outdoor exercise significant effects were noted. Increased motor vehicle traffic has lead to summer smog where ozone accumulates in our cities when high pressure exists during the summer. These ozone concentrations reach levels associated with adverse effect on both normal and asthmatic subjects. In addition, ozone can enhance response to inhaled allergens, increasing both the immediate and late response to allergens. Ongoing inflammation of certain cells in the body, known as T or TH2 cells, or possibly T regulatory cells can modify the response to ozone. Particulate and gaseous pollutants such as diesel exhaust particles and ozone can affect both the upper and lower airways stimulating and exacerbating cellular inflammation via interaction with the innate immune system. A number of anatomic changes occur in the elderly which include atrophy of the respiratory muscles, loss of lung wall surface and muscle fibers as a result of continued exposure to pollutants, infections and metabolic or hormonal changes associated with aging. A European study found that hospital admissions for air pollutants including ozone in the elderly was a risk for ischemic disease. More recent US studies reported that concentrated ambient fine particles plus ozone lead to a significant increase in diastolic blood pressure and increased levels of ambient sulfate and ozone may increase the risk of supraventricular arrhythmia in the elderly. In addition, a study in 2007 reported that small temporal increases in ambient course particulate matter are sufficient to affect circulating eosinophils, heart rate variability, cardiopulmonary and lipid parameters in adults with asthma It is often difficult to distinguish asthma from a heart condition in seniors due to atypical symptoms. Seniors with respiratory problems should be alert to high ozone levels as reported by the media and posted on highway signs and remain indoors on those days. Marianne Frieri, MD, PhD, FAAAAI, is a Fellow of the American Academy of Allergy, Asthma and Immunology (AAAAI) and a practicing allergist/immunologist in East Meadow, NY. |
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© 1996-2008 · All Rights Reserved · American Academy of Allergy Asthma & Immunology |
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