National Ambient Air Quality Standards (NAAQS): Specific primary standards established by the Environmental Protection Agency (EPA) for common air pollutants like carbon monoxide, ozone, particulate matter, sulfur dioxide, nitrogen dioxide, and lead.
Maximum Contaminant Level (MCL): Primary drinking water standards set by the EPA that define the maximum allowable concentration of contaminants in public water systems.
Soil Screening Levels (SSLs): Primary standards developed by environmental agencies to determine safe levels of contaminants in soil, ensuring protection of human health and the environment.