Any time you're removing old flooring you should be cautious about the air quality in the space. Asbestos or other potentially harmful fibers, while not likely present in your hardwood, could be in the underlayment or old flooring underneath. It's a good idea to wear a dust mask at a minimum, a respirator is even better. Open as many windows as you can, and a box fan or two, set on window sills and blowing out, can help to help to force the dust outside faster.