我老婆每年春秋天在休斯顿都过敏的厉害，但是一回上海就好了。以前在国内也没这个毛病。。

她也是到了美国4-5年以后才开始的。后来发现他对松树的花粉特别敏感，我们以前住的房子前后院有6棵大松树。现在的房子周围没有松树，就没有敏感的很厉害。
还有现在我们楼下是瓷砖地，楼上是地板，再没有地毯了，好像也有减少过敏的可能性。

以下是过敏的原因之一：During a process called sensitization, your immune system mistakenly identifies a harmless airborne substance as something harmful. Your immune system then starts producing antibodies to this harmless substance. The next time you come in contact with the substance, these antibodies recognize it and signal your immune system to release chemicals such as histamine into your bloodstream. These immune system chemicals cause a reaction that leads to the irritating signs and symptoms of hay fever.