On May 29, 2012, the Central District of California dismissed a lawsuit filed by a number of environmental groups seeking to apply the Resource Conservation and Recovery Act (“RCRA”) to any gaseous emissions that have the potential to form a solid or liquid residue.

In Center for Community Action and Environmental Justice, et al. v. Union Pacific Corp., et al.,1 the district court considered whether RCRA—a statute that governs the storage, treatment, transportation, and disposal of solid and hazardous waste—could be applied to diesel particulate matter (“DPM”) emitted by locomotives, trucks, and other equipment at various railyards across California. The court held that RCRA does not apply to diesel exhaust both because DPM is not a “solid or hazardous waste” under RCRA and also because Congress intended the Clean Air Act (“CAA”) to regulate diesel emissions comprehensively.