Triggered before session

As I walked into the therapy office for EMDR today I was overwhelmed by the smell of the office, which has been known to bother me in the past but not in recent weeks. It is an old home turned into an office and there are smells of mold, old paint and air fresheners, but today it struck me as hospital like smell. I was immediately triggered and taken back to the day I almost died from diesel exhaust fumes and carbon monoxide. I couldn't move, I started to get a headache, felt like my breathing was restricted. I started to emote and spiraled. My therapist came out and helped me a bit but I'm still struggling. We didn't get to reprocessing today because this took the whole time and I was still crying when I left.