[fixermark]

If I'm understanding correctly, the overall hypothesis is that the allergy response is triggered by exposure to other toxins at low levels that prime the immune system to respond to the toxin, but the priming is inaccurate; the histamine-generating machinery does a quick-and-dirty approximation of the chemical that triggered the cellular damage, and while rounding up whatever industrial monomer irritated your nasal passages, it also snags the molecular tags of surrounding pollen and other common chemicals.

As a side-effect, the system gets primed against the actual threat but also primed against benign foreign chemicals as well. The change in the ecosystem that has caused this defense mechanism to become a hindrance is the introduction of novel chemicals to our daily lives that trip low levels of immuno-response (or increase in chronic exposure to those chemicals due to a general shift to indoor living, where the chemicals just sit in the environment and bathe us in them), providing the opportunity for the immune system to sensitize to frequenltly-contacted benign chemicals.