Carbon Credits but for NOX?

[tander]

Just purchased carbon credits for the first time this year. They don't really solve the problem imo but it seems like a nice small thing to do. Anybody heard of something like that but for other emissions like NOX? At a local level those are a lot more important to me than carbon.

 

[Joel Weber]

What are your local sources of NOX, and what do you expect would be the most cost effective way to improve the situation?