Environmental hazard

An environmental hazard is a substance, state or event which has the potential to threaten the surrounding natural environment or adversely affect people's health, including pollution and natural disasters such as storms and earthquakes. It can include any single or combination of toxic chemical, biological, or physical agents in the environment, resulting from human activities or natural processes, that may impact the health of exposed subjects, including pollutants such as heavy metals, pesticides, biological contaminants, toxic waste, industrial and home chemicals. Human-made hazards while not immediately health-threatening may turn out detrimental to a human's well-being eventually, because deterioration in the environment can produce secondary, unwanted negative effects on the human ecosphere. The effects of water pollution may not be immediately visible because of a sewage system that helps drain off toxic substances. If those substances turn out to be persistent (e.g. persistent organic pollutant), however, they will literally be fed back to their producers via the food chain: plankton -> edible fish -> humans. In that respect, a considerable number of environmental hazards listed below are man-made (anthropogenic) hazards. Hazards can be categorized in four types — chemical, physical, biological, and psychological. Chemical hazards are substances that can cause harm or damage to humans, animals, or the environment. They can be in the form of solids, liquids, gases, mists, dusts, fumes, and vapors. Exposure can occur through inhalation, skin absorption, ingestion, or direct contact. Chemical hazards include substances such as pesticides, solvents, acids, bases, reactive metals, and poisonous gases. Exposure to these substances can result in health effects such as skin irritation, respiratory problems, organ damage, neurological effects, and cancer. Physical hazards are factors within the environment that can harm the body without necessarily touching it.