Biogas and Human Health

California Legislative Assembly Bill 1900 (AB 1900, Statutes of 2012, Chapter 602) requires the California Public Utilities Commission (CPUC) to develop standards for certain constituents found in biogas to protect human health and ensure pipeline safety.  Once biogas meets the standards, it is then considered to be biomethane that may be injected into utilities’ natural gas distribution systems.  In support of the rulemaking process, the Office of Environmental Health Hazard Assessment (OEHHA) and the Air Resources Board (ARB) are mandated to perform specific tasks and provide recommendations to the CPUC:

  1. OEHHA, in consultation with ARB and others, compiles a list of constituents of concern present in biogas at levels substantially higher than those found in natural gas that could pose a health risk to consumers, workers, or other members of the public.  OEHHA is to update this list at least every five years.
  2. OEHHA determines health protective levels for the constituents of concern.
  3. ARB identifies realistic exposure scenarios and, in consultation with OEHHA, identifies the potential health risks associated with the exposure scenarios using the OEHHA health protective levels, and determines health-protective concentrations for these constituents in biogas.
  4. ARB, in consultation with other Cal/EPA boards and departments, defines monitoring and reporting requirements to ensure that health-protective levels will be maintained.

The ARB-OEHHA joint recommendations document (Recommendations to the California Public Utilities Commission Regarding Health Protective Standards for the Injection of Biomethane into the Common Carrier Pipeline) was finalized and submitted to the CPUC on May 15, 2013, and is available at the ARB website:

OEHHA is also providing the following MS Excel spreadsheet as supplemental information for reviewers. It contains additional details on the risk calculations carried out in the Recommendations document.