Air pollution is a growing problem throughout the world. Indoor air pollution is one of the leading cause of lung cancer. Families in developing countries use open stoves for cooking and heating their homes. These homes do not have proper ventilation. The smoke, which is full of chemicals and carcinogens, get trapped inside where families eat and sleep. Outdoor pollution also cause disease and illness, especially in industrial cities such as Beijing, China, where cancer is the leading cause of death. China relies heavily on coal, which is considered the dirtiest source of energy. According to the European Union, only 1% of urban dwellers in China breathe clean air on an average day. Neighboring countries including Japan and Korea receive much of China's pollution in the form of acid rain. This pollution results mainly from the coal powered factories, which produce inexpensive goods for North American and European consumer. Outdoor air pollution is also a concern in many wealthy countries. Those who live and work in urban centre such as Log Angeles or Toronto experience many warm days beneath a layer of smog