Asthma-like syndrome/acute non-allergic respiratory symptoms
Inhalation of organic dust in the agricultural environment may also give rise to another non-allergic respiratory response, which has been described as ‘asthma-like syndrome’. The main clinical feature is wheeze and breathlessness that tends to improve as the working week progresses. The prevalence of symptoms in agricultural populations has been reported in a few studies from Europe [53,54] and is of the order of 20–50%. Acute cross-shift reductions in FEV1 (usually ~10% or less) have been observed among both grain and livestock workers [55–57]. The distinguishing feature from asthma is the absence of persistent airways hyper-responsiveness.Grain and cotton dust are the most well-established causes, but ammonia and endotoxins have also been implicated. Increasingly, studies have used personal sampling methods in order to assess exposures [55–57]. Results indicating a significant dose–response relationship between symptoms and dust, ammonia and endotoxins have been reported [56].