We had to tour an office today with safety. The lady is complaining of nausa, burning eyes, nose and throat. Sometimes she has headaches. All which clear up after a short time outside. Wed. she went to the ER. The tour was a little too structured for me. Two things I couldn't help but notice, a filter type, that I've never seen before over the supply vent. Also a Bionaire tower fan that was fairly thick. It had a foam filter inside it, looked like it had a Ionizer indicator lamp. Looked for a number on it, but didn't see anything. A RTU serves a large area, and we don't really have any other complaints. She has her own VAV, with the only source of air from the RTU, no ceiling air is recirculated. Everything is three years old, and very clean. I'm thinking the tower fan is putting out Ozone.