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Occupational asthma is an occupational lung disease and a type of asthma. Like other types of asthma, it is characterized by airway inflammation, reversible airways obstruction, and bronchospasm, but it is caused by something in the workplace environment. Symptoms include shortness of breath, tightness of the chest, nasal irritation, coughing and wheezing. The first person to use it in reference to a medical condition was Hippocrates, and he believed that tailors, anglers and metalworkers were more likely to be affected by the disease. Although much research has been done since, the inflammatory component of asthma was recognized only in the 1960s. Today, asthma affects as much as 15% of the Canadian population,〔(C-Health: Asthma in Canada(2007) )〕 a statistic reflective of other developed countries, and has increased fourfold in the last 20 years. Various reasons can be identified for this increase, including increase environmental pollution, better diagnostic ability, and greater awareness. Approximately 21% of the adults affected by asthma report an aggravation of their symptoms while at work and an improvement when away, which implies that they may be suffering from occupational asthma. In the United States, occupational asthma is the most common occupational lung disease.〔 At present, over 400 workplace substances have been identified as having asthmagenic or allergenic properties.〔((T78) Occupational Asthma : Table of agents, products and substances which can cause asthma )〕 Their existence and magnitude vary by region and industry and can include diisocyanates, acid anhydrides, plicatic acid, and platinum salts (all low molecular weight agents), and animal protein, enzymes, wheat, and latex (high-molecular weight agents).〔〔 For example, in France the industries most affected are bakeries and cake-shops, automobile industry and hairdressers, whereas in Canada the principal cause is wood dust, followed by isocyanates. Hypersensitivity pneumonitis is a related condition, with many occupational examples (e.g. flock worker's lung, farmer's lung, and indium lung). However, although overlapping in many cases, hypersensitivity pneumonitis may be distinguished from occupational asthma in that it isn't restricted to only occupational exposure, and involves type III hypersensitivity and type IV hypersensitivity rather than the type I hypersensitivity〔(【引用サイトリンク】title=Lecture 14: Hypersensitivity )〕 of asthma. Also, unlike asthma, hypersensitivity pneumonitis targets lung alveoli rather than bronchi.〔Page 503 in: 8th edition.〕 == Signs and symptoms == Less than five years of exposure or a single exposure to a high-concentration agent can result in symptoms. Coughing, wheezing, nasal irritation, shortness of breath, and chest tightness are the most common symptoms, all of which worsen after work and improve during time away from work. Pre-existing asthma can be exacerbated by similar agents. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Occupational asthma」の詳細全文を読む スポンサード リンク
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