Air regulators today face complex challenges but also have enormous opportunities. This brief discusses a set of air regulatory tools that can help empower states and local air districts to do more to reduce harms caused by air pollution to communities.

The brief finds that air regulators possess significant, often untapped, legal authority to regulate stationary sources, like warehouses, in a way that addresses pollution from mobile sources, such as delivery trucks. The brief details options for adopting and enforcing so-called indirect source rules (ISRs), which are the topic of a slate of new bills in 2025.  

This analysis suggests that ISRs are effective and well-tested regulatory tools that are on strong legal footing and deserve to be used more often and more robustly by local air districts and state environmental agencies across the country. 

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