It could be a combination of hay fever and chemicals in the anti-stain coating.
There are plenty of things which don't irritate my eyes, throat and ears for most of the year (such as perfumes, deodorant sprays, chalk dust, etc) but which produce these symptoms for me during the hay fever season, even though the direct effects of the hay fever are hardly noticeable. It often appears that I've suddenly become allergic to lots of chemicals and odours when, in fact, all that has happened is that the pollen has caused almost unnoticeable irritation, which is suddenly made a thousand times worse by other substances.
Treating the hay fever (with antihistamine tablets) soon corrects the problems.
Chris