Indoor air pollution is bad for your health but indoor air pollution is not responsible for a large percentage of deaths in the world.
About 69 percent of deaths are causes by strokes and heart attacks while around 15% to 20% of deaths are caused by indoor air pollution.
Indoor air pollution can happen from cooking, smoking, carbon monoxide, carbon dioxide, Radon, Particulate Matter, Lead, Asbestos and Formaldehyde/Pressed Wood Products.
Outdoor air pollution can also seep indoors which can lead to the indoors being polluted by those outdoor pollutants.