As Figure 3.19 shows, wealth and rural-urban disparities are important across regions, with low-income and rural households relying on solid fuels to a much greater extent than high-income and urban households. In 2012, indoor air pollution caused 4.3 million premature deaths, with women and girls accounting for 6 out of every 10 of these. As a cause of non-communicable diseases such as chronic obstructive pulmonary disease, lung cancer and heart disease, indoor air pollution has become a major environmental health concern.