Screening Levels
The Screening Levels are chemical-specific concentrations for individual contaminants in air, drinking water and soil that may warrant further investigation or site cleanup.
| Resident Soil | Industrial Soil | Resident Air | Industrial Air | Tapwater |
| 0.18 mg/kg | 0.78 mg/kg | 0.15 μg /m3 | 0.64 μg /m3 | 0.3 μg/L |
Maximum Residual Disinfectant Level
The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
MRDL: 4.0 mg/L
National Primary Drinking Water Regulations for “Chlorine” (Last Updated by the EPA in May 2009)
Units
| Abbreviation | Meaning | Notes |
|---|---|---|
| mg/kg | mass of chemical (milligrams, mg) per mass of soil (kilogram, kg) | Equivalent to parts per million (ppm) |
| μg/m3 | mass of chemical (micrograms, mg) per volume of air (cubic meter, m3) | This can be converted to ppm using the molecular weight of the chemical |
| μg/L | mass of chemical (micrograms, μg) per volume of water (liter, L) | Equivalent to parts per billion (ppb); divide by 1,000 to get ppm |
| mg/L | mass of chemical (milligrams, mg) per volume of water (liter, L) | Equivalent to parts per million (ppm) |
For more information about these units and their conversion factors, visit https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.files/fileid/14285.