I gave thought to everything you mentioned and...no.

I will say....I was opening the bedroom window so both cats could look outside and hear things too. We have been smack in the middle of pollen and blooms. Took Max to the Vet this AM and he said their is no issues with his lungs. Just simple allergies. He gave max a steroid and antibiotic shot. He said these sneezing spells can last 1-2 weeks. The weather is BEAUTIFUL outside but I'm keeping the windows closed for now.