During the burning of coal in small and simple home stoves for cooking and heating (China and India), a significant emission of pollutants (between 10% and 30%) are the products of incomplete combustion: carbon monoxide, nitrogen dioxide, benzene, formaldehyde, benzo[a]pyrene, 1,3-butadiene, formaldehyde, and polycyclic aromatic hydrocarbons (PAHs) vary greatly depending on the type of coal and the burning conditions. Such coals contain pollutants such as sulfur, arsenic, lead, or mercury, which are released into the air during combustion. Combustion of coal at high temperatures results in the emission of large amounts of nitrogen oxides, and two types of particles of matter (PM) occur: respirable particulate matter (<10 μm, called PM10) and respirable particulate matter (<2.5 μm, called PM2.5). PAHs released from particles deposited in the bronchial airways are absorbed into the circulation over several hours, but PAHs released from particles in the alveolar airways are absorbed within minutes. Some amounts are rapidly metabolized, bind to DNA, and produce genotoxic effects (formation of DNA adducts). Benzo[a]pyrene (PAH compound) forms adducts in DNA (genotoxic mechanism). In summary, there is sufficient evidence for the carcinogenicity of indoor coal burning and the development of lung cancer. Its main urinary metabolite is 1-hydroxypyrene.