The short-term effects of smoking include respiratory illnesses including colds, coughs, pneumonia, and bronchitis. Children exposed to second-hand smoke experience higher rates of ear infections, asthma, and lower respiratory infections than children who live with non-smokers. The long-term effects of smoking are extensive. Smoking causes cancers of the lungs, mouth, throat, kidneys, bladder, stomach, pancreas, and cervix. Approximately one-third of all forms of cancer have been linked to smoking and tobacco use in general. Ninety-percent of lung cancers have been linked to smoking. Smoking causes chronic obstructive pulmonary disease (COPD), emphysema, chronic bronchitis, and doubles the risk of stroke.