Pollen is a common offender, just because we encounter so much of it, but there's a long list of substances: dust, animal dander, insect venom, medications, certain foods, that can send your immune system into overdrive.

花粉是常见的入侵者，是因为我们经常能够遇到，但还有很多其他类似的物质：如灰尘，动物皮屑，昆虫毒液，药物，特定食物，它们会使得你的免疫系统过度工作。