Legal Limit
The maximum amount of a pollutant or contaminant that government regulators (like the EPA) allow in air, drinking water, or soil before the area or supply is considered out of compliance with the law.
Related terms
National Ambient Air Quality Standards Federal standards set by the EPA that establish the maximum allowable levels of six common air pollutants (the criteria pollutants) considered harmful to public health and the environment. Maximum Contaminant Level The highest concentration of a specific contaminant that the EPA legally allows in public drinking water. Set per chemical based on health risk and treatment feasibility. Parts Per Million A ratio expressing concentration as one unit of solute per million units of solution. For dilute aqueous samples, 1 ppm ≈ 1 mg/L. Parts Per Billion A unit 1,000 times more sensitive than parts per million, used for very low concentrations of contaminants. One ppb equals one part pollutant per one billion parts of medium. Environmental Protection Agency The U.S. federal agency responsible for setting and enforcing pollution standards for air, water, and soil, and for regulating hazardous chemicals.