Environmental justice advocates have been heavily lobbying officials at the Air Resources Board, lawmakers at the Capitol and other policymakers to cut incentives for dairy digesters. They argue the methane-capturing technology is worsening air pollution in neighboring disadvantaged communities and have called for a comprehensive evaluation.
A new CARB-funded study has delivered on those calls and found no cause for alarm. Researchers at UC Davis and the Massachusetts Institute of Technology found that widespread digester adoption would have only minor effects on local air quality and would not harm public health.
The analysis shows that the broad adoption of digesters in the San Joaquin Valley, the heart of the nation’s dairy production, would at worst lead to less than 0.1 additional deaths per 100,000 people. That is more than 100 times smaller than the risk posed by seasonal flu.

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 In that scenario, biogas would be powering all electricity production in the valley and yet lead to minor emission increases, not enough to influence federal air standards. The study also found it would not affect racial disparities, either in the valley or in the Bay Area or Sacramento region.
In a statement to Agri-Pulse, a CARB spokesperson noted that the agency “continues to find opportunities to study ways to reduce air pollution emissions and focus on areas that are the center of current public discussions such as dairy emissions.” The study supports digesters while “appropriately identifying the need to transition away from combustion technologies.”