Environmental Causes of Asthma.
Seminars in respiratory and critical care medicine
Environmental factors which cause asthma are those that induce airway inflammation with eosinophils (more common) or neutrophils along with airway hyperresponsiveness (AHR). The most common of these (indeed the most common cause of asthma) are IgE-mediated inhalant allergen exposures. Allergen-induced AHR and inflammation are both associated with the allergen-induced late asthmatic response (LAR). Although allergens were previously recognized only as causes of symptoms and bronchoconstriction in asthmatics, we now appreciate them as causes of the fundamental pathophysiologic features of asthma. Low-molecular-weight chemical sensitizers, causes of occupational asthma, also cause asthma in a manner analogous to allergen. Acute irritant-induced asthma (reactive airways dysfunction syndrome) following a very heavy irritant exposure and chronic irritant-induced asthma following repeated high exposures can also induce persistent or permanent changes (inflammation and AHR) consistent with asthma. Textile dust exposure produces a different form of airway disease (byssinosis) which is less frequently observed currently. Environmental exposure to tobacco smoke facilitates the development of asthma in children. Personal smoking and environmental air pollution have an inconsistent and likely generally small effect in causing asthma.
- 1Division of Respiratory, Critical Care and Sleep Medicine, Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
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||Last Modified: 2016-03-27