Attempts to secure more energy, food, and infrastructure leave a trail of environmental contamination and human health hazards. Coal is a fossil fuel and nonrenewable energy source that is combusted and used to generate electricity. A coal-fired power plant is a prodigious generator of environmental pollution, releasing large quantities of particles as aerosols in the atmosphere. The inhalation of hazardous substances such as coal micro-particles, nanoparticles, and its by-products constitutes an invisible risk to human health. Although coal is predominantly composed of carbon, there are many other constituents including sulfur, nitrogen, organometallic compounds, and minerals, that contribute to the formation of extremely toxic secondary compounds that come in contact with the atmosphere. The continuous inhalation of these hazardous substances triggers many diseases such respiratory and cardiovascular disease, systemic inflammation, and neurodegeneration. Due to coal heterogeneity, it is extremely complex to establish all the effects of the molecules in the organism. Each cell can undergo different modifications depending on the stressing molecule. On that account, inhaling air contaminated with these particles can be highly dangerous and unpredictable. This review covers the impact of coal inhalation on the lungs, immune system, heart, reproductive system, brain, DNA, and, in general, the human health. For this review, Medline and Scopus databases were accessed, including human epidemiological, review studies, and coal characterization studies over the years. Coal as an energy source must be utilized with appropriate measures of environmental protection and to safeguard human health.
