Timeline

Jan 2022 - Dec 2023

Description

The dairy industry in California emits large amounts of methane (CH4) that contributes significantly to the state’s overall Greenhouse Gas (GHG) budget. Reducing CH4 emissions has become a key priority for dairy farms in support of California’s GHG reduction goals. Anaerobic digesters designed to capture CH4 from animal manure present a practical option for reducing CH4 emissions, but a comprehensive evaluation of the local air quality impacts of this technology has not been previously undertaken.

The simplest digester configurations decrease local emissions of volatile organic compounds (VOCs) but increase emissions of oxides of nitrogen (NOx), potentially changing local air quality. Here, we evaluate the air quality implications of widespread digester adoption in the year 2050 across the San Joaquin Valley (SJV) in central California, which is home to the highest concentration of dairy farms in the state.

Our research results indicate that baseline dairy emissions make minor contributions to air pollutant concentrations in 2050. A health impact analysis shows that the widespread use of dairy digesters would result in fewer than 0.1 additional deaths per 100,000 people due to changing air pollution. For comparison, this level of mortality change is more than 100 times smaller than the risk posed by seasonal flu. Further, Environmental Justice analysis indicates that the implementation of digesters will not influence the exposure disparities among different racial groups in either the SJV or the surrounding San Francisco Bay & Sacramento area.

These findings suggest that dairy digesters can be widely adopted in central California to reduce GHG emissions with minimal effect on regional air quality and public health.

Publication

  • Jiang, J., Li, Y. and Kleeman, M., 2024. Air quality and public health effects of dairy digesters in California. Atmospheric Environment, 331, p.120588. Link

Presentation

  • Jiang, J., et al., Dec 2023, Long-Term Air Quality and Health Effects of Dairy Digesters in the Future Northern California, International Aerosol Modeling Algorithms Conference 2023.
  • Jiang, J., et al., Oct 2022, Long-term Air Quality and Health Effects of Dairy Digesters in the Future San Joaquin Valley, American Association for Aerosol Research (AAAR) 40nd Annual Conference.