Environmental medicine is a multidisciplinary field involving medicine, environmental science, chemistry and others, overlapping with environmental pathology. It can be viewed as the medical branch of the broader field of environmental health. The scope of this field involves studying the interactions between environment and human health, and the role of the environment in causing or mediating disease. This specialist field of study developed after the realisation that health is more widely and dramatically affected by environmental factors than previously recognized. Environmental factors in the causation of environmental diseases can be classified into: Physical Chemical Biological Social (including Psychological and Culture variables) Ergonomic Safety Any combination of the above In the United States, the American College of Occupational and Environmental Medicine (OCOEM) oversees board certification of physicians in environmental (and occupational) medicine. This board certification isn't recognized by the American Board of Medical Specialties. Current focuses of environmental medicine While environmental medicine is a broad field, some of the currently prominent issues include: The effects of ozone depletion and the resulting increase in UV radiation on humans with regards to skin cancer. The effects of nuclear accidents or the effects of a terrorist dirty bomb attack and the resulting effects of radioactive material and radiation on humans. The effects of chemicals on humans, such as dioxin, especially with regards to developmental effects and cancer. Radon gas exposure in individuals' homes. Air and water pollution on the health of individuals. Mercury poisoning and exposure to humans through including fish and sea life in their diet. Lead poisoning from leaded gasoline, paint, and plumbing. Water-borne diseases Food poisoning Indoor air quality According to recent estimates, about 5 to 10% of disability-adjusted life years (DALY) lost are due to environmental causes. By far, the most important factor is fine particulate matter pollution in urban air. Scope of environmental medicine Environmental medicine is concerned primarily with prevention. Food-borne infections or infections that are water-borne (e.g. cholera and gastroenteritis caused by norovirus or campylobacteria) are typical concerns of environmental medicine, but some opinions in the fields of microbiology hold that the viruses, bacteria and fungi that they study are not within the scope of environmental medicine if the spread of infection is directly from human to human. Much of epidemiology, which studies patterns of disease and injury, is not within the scope of environmental medicine, but e.g. air pollution epidemiology is a highly active branch of