职业灰尘和化学品（蒸汽、刺激物和烟雾）；
occupational dusts and chemicals (vapors, irritants, and fumes);
一种观点认为，过敏之所以会产生，是由于人们在童年时期当免疫系统尚未成熟时曝露于某些刺激物之下，如灰尘或动物毛屑。
One view is that allergies can develop as the result of childhood exposure to certain irritants, such as dust or animal dander, while the immune system is not yet mature.
这些刺激可能包括灰尘和污染，香烟烟雾，和其他刺激物。
These irritants may include dust and pollution, cigarette smoke, and other irritants.
应用推荐