It is dangerous to breathe in. Right now there is not enough data to determine how long you have to be exposed to wood dust and in what quantities until it presents a cancer danger. What does not take so long to develop from breathing wood dust is industrial asthma. Once you get it you have it for life. Its effects are deleterious and lasting.
Smoking increases the risks and dangers of everything exponentially.
You need to wear a respirator both when woodworking and finishing. I bought a decent mask with fancy filters on either side. It didn't take that much getting used to. I've noticed immediate benefits since using it with far less nasal congestion and the elimination of brown crud. E-mail us and let us know what you think.