No fog here in alberta .... dry as a bone. I know I react to dry air a bit but it's different symptoms. Dry air makes me cough and cough and cough where the symptoms are more itchy lungs that feel swollen and heavy.
Now a week or so later of it being a bit colder (most of the grass is covered with snow and the warm spells aren't melting it as much) the symptoms are pretty much gone.
There must be a mould that is common later into the fall that pops up whenever the snow starts to melt.
Do think your lungs are reacting to the cold air? Or are is there more fog and any inversions that trap any possible irritants (pollutants)?
I used to get pretty bad hayfever in the fall/early winter (as well as the killer hay fever I still get in the spring). I honestly think my fall problems were caused by the trees- cedar, alderwood, and/or pine. The problem seemed to get worse if I went to into a forest and it completely disappeared after I moved to Australia. So whatever was causing my problem is back in the Washington State.
I will say I've got non-allergenic rhinitis, which basically means I have never tested positive for antibodies because my body reacts on a chemical level, bypassing the immune system completely. That being said I still react (sometimes violently) to about a dozen things. This includes the regular trees, molds, and dusts that are tested for on the common allergy tests. But I also get a reaction from perfume and pretty flowers like lilacs, jasmine, and lilies.
So you may want to talk to your dr about non-allergenic rhinitis, which is basically a chemical sensitivity that bypasses the immune system but still gives you all the feel of allergies, different trees which could be an issue in the fall, and maybe the odd balls out of the allergy tests that could be a factor.