ABSTRACT
Environmental risks can result from contact with a toxic material or contaminant via the environment. A human health risk can be experienced by individuals or populations from contact with an environmental contaminant through inhalation, ingestion, or skin contact. Such risks can be acute (short-term) or chronic (long-term) in nature and can range from mildly irritating to life threatening. Risk is generally defined as the potential for an unwanted negative consequence or event. The term indoor environment, as used encompasses all enclosed spaces occupied by humans, including home, work, shopping, education, entertainment, and transportation. Humans have always estimated the risks of their actions or inactions in making personal decisions. However, the process was either intuitive or empirical until the mid-17th century when probabilities began to be described mathematically, initially to calculate gambling odds more precisely and later to calculate the odds of life events, such as the expected age of death for life insurance policies.
