Open windows when refinishing floors?

Keep windows closed in rooms that are getting refinished. Windows in distant rooms can remain cracked open.

Especially when using a water-based finish, the first coat will tend to raise the grain of the wood. Even though the finish may seem dry after only a couple hours, let the finish dry more fully overnight. To take down the raised grain (and any bumps caused by dust or insects getting into the finish) use a 16" dia. floor buffer or an orbital floor sander with maroon abrasive pad (the pad is a large version of the green scrubby pads for washing dishes) or with a worn #120 grit or finer sanding screen. Then sweep, vacuum and hand wipe with damp rag or tack rag the entire floor. Repeat this procedure if dust bumps or insects get into later coats of finish.

Otherwise, remaining coats of finish can be applied without buffing as soon as the previous coat is dry to the touch.

You are not being overly concerned. Particles can easily end up sticking to the finish.

What you might want to try is hanging a sheet in the doorway of the room getting the finish. If you can, put fans in the windows facing outward. This will draw fresh air through the sheet on the doorway, and send most of the smell out the windows.

I'm going to be facing the same thing when I sand & do the finish on my kitchen floor. All the fumes will hopefully go out the windows & no dust & junk coming in.