Generally speaking, wood stoves are marvelous inventions which bring a cozy comfort to the homes of their owners, and slash away at heating bills in the process. With strict safety and environmental guidelines, modern stoves are safer and more efficient than ever before. However, stoves sill present the possibility of harm to certain high-risk individuals.
Children are at risk from stoves because their lungs are only finishing development and exposure to carcinogens or smoke is more harmful than it is to adults. The elderly, as many more elderly suffer from shortness of breath and other health conditions, and anyone with heart or lung disease such as emphysema or asthma.
Short term exposure to the smoke from wood stoves (especially if the wood stove system is not cleaned regularly) tends to aggravate existing lung conditions, leading to more frequent asthma attacks, bronchitis, and allergies. Also, smoke has a very negative effect on lung infections like pneumonia.
Long term effects from a smoky stove are more lurking, but have been shown to cause a general increase in the frequency of heart and lung disease, hospital visitation, and chronic bronchitis. Once the smoke particles are inhaled they pass deep into the human lung where they are retained. With frequent inhalation this build up damages cells and gas exchange linings, diminishing lung efficiency and capacity over a period of years.
However: a well-kept stove stocked with seasoned wood will have very little impact on your health or the health of children. There should never be a smell of smoke while the stove is in use and if one is detected (by smell or a smoke alarm) the stove should be checked, possibly scheduled for maintenance.