Many household building materials, carpet and furnishings will emit a chemical smell, especially when they are new. In small doses this will not affect most people. But large concentrations of airborne chemicals can cause irritation to the eyes and throat, as well as constant tiredness and impaired cognitive functions. These Volatile Organic Chemicals (VOC) are dangerous specifically because they are organic, and can interact with human physiology.
New carpet is notorious for giving off chemicals like formaldehyde. This dissipates after a few weeks, but it can cause health problems for residents when it is first installed. Airing out rooms, using bi carb of soda on new carpet, use of air filters and keeping indoor plants all help to reduce VOC in the air.
One great advantage of natural wood flooring is the near absence of any dangerous chemicals. Only trace amount of these chemical exist in natural wood, and these do not seem to pose any threat.
There can be an issue with VOC when protective coatings are applied to timber floors. Polyurethane coatings will usually emit VOC for a few days after application. Oil based polyurethane emits more VOC than water based varieties.
Newer varieties of polyurethane are now very low VOC, or VOC free.
Timber floors are one of the healthiest options. The stains and protective coatings are a healthy and safety concern, but proper precautions should prevent any serious problems.
Floor sanding allows a timber floor to be restored to a virtually new appearance. It can then be re-coloured to change the décor, or simply left as a new floor.