Health-Based Rules and Guidance for Air
The Minnesota Department of Health (MDH) develops health-based rules and guidance to evaluate potential human health risks from exposures to chemicals in ambient air. This guidance is developed at the request of MDH programs and other state agencies, such as the Minnesota Pollution Control Agency (MPCA).
To see the available guidance for ambient air, please visit the Air Values Table.
A Health Based Value (HBV) is the concentration of a chemical (or a mixture of chemicals) that is likely to pose little or no risk to human health. MDH develops HBVs for water and for ambient air.MDH develops HBVs when Minnesota agencies need guidance for chemicals that do not have HRVs. MDH may also calculate HBVs to update an existing value if there is significant new scientific information for the chemical and/or to apply new risk assessment methods.
An ambient air HBV is expressed as micrograms of chemical per cubic meter of air (µg/m3). HBVs are developed to protect human health for a specified length of exposure (e.g., one hour, one day, one month, a lifetime). HBVs for air are calculated using the methodology set in the Health Risk Values Rules. HBVs meet the same data requirements as Health Risk Values (HRVs).
HBVs have not been promulgated using the public process described by the Administrative Procedures Act (Minnesota Statutes Chapter 14). Instead, an HBV is technical guidance made available by MDH. These values may be used by the public, state and local risk managers, and other stakeholders to assist in evaluating potential health risks to humans from exposures to a chemical.
HRVs also may be expressed as micrograms of chemical per kilogram body weight per day of exposure (µg/kg-day). These values, called multi-media HRVs (HRVms), are developed for chemicals emitted to ambient air where multi-media exposures are important to public health. These values are based on oral exposures.
HRVs are developed using the best peer-reviewed science and public health policies available at the time of their development. The HRVs are derived using U.S. Environmental Protection Agency (US EPA) guidelines and the standard methodology used to derive US EPA's Reference Concentrations (RfCs) and California EPA's Reference Exposure Levels (RELs). HRVs are based solely on information about health effects. Other factors such as the ability to detect or monitor a chemical, the cost of controlling a chemical, or background concentrations of a chemical are not considered.
HRVs are classified as acute, subchronic, and chronic based on the length of the exposure to a chemical or mixture. Acute HRVs are compared to one-hour averaged concentrations of chemicals or defined mixtures of chemicals in ambient air. Subchronic HRVs are compared to a 13 week averaged concentration of a chemical or defined mixture of chemicals in ambient air. Chronic HRVs are compared to an annual average concentration of a chemical or defined mixture of chemicals in ambient air.
MDH develops RAA when stakeholders need guidance for chemicals that do not have existing guidance or standards. MDH may also calculate RAA to update an existing value if there is significant new scientific information about the chemical or our risk assessment methods have been updated.
RAA has not been promulgated using the public process described by the Administrative Procedures Act (Minnesota Statutes Chapter 14). Instead, RAA is technical guidance made available by MDH. These values may be used by the public, state and local risk managers, and other stakeholders to assist in evaluating potential health risks to humans from exposures to a chemical. RAA is not likely to change unless significant new data become available.
MDH also develops RAA on a case-by-case basis for specific conditions or specific sites. It is not appropriate to apply this site-specific RAA to other sites without consulting with MDH.
For more information, see links below or contact the Health Risk Assessment Unit.