People walk and ride the pathway on the Panorama Bluffs on Sept. 8, 2020. The air quality index was at 156. An AQI over 150 is considered unhealthy and potentially hazardous to the general population.

In a case that could affect certain large, local businesses venting exhaust, environmental justice advocates are gearing up for a court fight with the region’s air district over its system of crediting commercial operations that buy offsets to make up for their emissions.

Five activist groups sent the San Joaquin Valley Air Pollution Control District a notice March 21 saying they plan to file suit in May alleging the agency has failed to correct its own past reports — and therefore has additional work to do under the federal Clean Air Act — based on faulty calculations for how much pollution needed to be offset through measures such as emission reduction credits, or ERCs.