My landlord is upstairs putting a new finish on hardwood floors. There is no ventalation and the fumes are horrid down here in my office (I'm at work and can't leave). How toxic are Polyurathane fumes? I'm 4 months pregnant. I'm scared there may be lasting effects from breathing this in. I have my door open but it's also 12 degrees outside and I'm afraid of getting sick too. Any advice?

I suppose its probably a bit late for this reply, but there is no reason to use solvent based polyurethane on floors. The newer acrylics are tougher, dry faster and are free of fumes. The solvents are various types petroleum solvents like acetone, propane, methyl ethyl ketone, ethylbenzene and others. Fumes are irritating and flammable. I can't really comment on pregnancy issues. Eye watering, headaches, nausea, dizziness, and loss of coordination are indications that solvent levels are too high and are signs you need to leave immediately.

Given the availability of alternatives, this is totally unnecessary. Ask him to stop and use an acrylic urethane.