Division of Respiratory, Critical Care and Sleep Medicine, Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
Semin Respir Crit Care Med. 2018 Feb;39(1):12-18. doi: 10.1055/s-0037-1606219. Epub 2018 Feb 10.
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.
引起哮喘的环境因素是那些引起气道炎症的因素，包括嗜酸性粒细胞（更常见）或中性粒细胞以及气道高反应性（AHR）。其中最常见的（实际上也是哮喘最常见的原因）是 IgE 介导的吸入过敏原暴露。过敏原引起的 AHR 和炎症都与过敏原引起的迟发性哮喘反应（LAR）有关。尽管过敏原以前仅被认为是引起哮喘患者症状和支气管收缩的原因，但我们现在认识到它们也是哮喘基本病理生理特征的原因。职业性哮喘的低分子量化学敏化剂也以类似于过敏原的方式引起哮喘。在受到非常重的刺激性暴露后，急性刺激性诱导的哮喘（反应性气道功能障碍综合征），以及在反复高暴露后，慢性刺激性诱导的哮喘，也会引起与哮喘一致的持续性或永久性变化（炎症和 AHR）。纺织粉尘暴露会产生一种不同形式的气道疾病（棉尘病），目前这种疾病不太常见。环境烟草烟雾暴露会促进儿童哮喘的发展。个人吸烟和环境空气污染对引起哮喘的影响不一致，可能通常较小。
