To those firing during the day,make sure you have proper ventillation. Proper ventillation is a unit that hangs directly (and close to) above the lid and evacuates the fumes. Opening windows is NOT proper ventillation. (the wind blows blows out and in) Everything we do in life has a synergistic effect in our bodies so don't tempt it. Also, YOU will be the one who will be exposed the most, as your students come and go from the environment all day.
Read the book "Artist Beware" for any other suggestions from using art supplies. The rule of thumb is "if you can smell it, it is generally not good for you". And shame on manufacturers for de-oderizing some of the products that are not good for you, like turpentine, paint thinners etc. In this way we are fooled to think they are not harming us.