I'm working on the bucket brigade air sample project and am trying to understand how community tools become "EPA-approved" (and whether this is a necessary step). An early version of the bucket was piloted through an EPA grant and having EPA approval is certainly helpful in some contexts to be able to push for improved monitoring. I'm trying to get a better sense of how and when - or if! -- EPA validation matters for community tools.
PA is a particle monitor not a gas sensor, but I think it's a good point of comparison since it's so widely used. I've looked at some of the EPA's past evaluation methodologies andper this question, I know that Purple Air has been field tested by the South Coast Air Quality Management District. Has this tool gone through a formal validation process? If so, what did that look like? If you've used Purple Air, has that made a difference in terms of its use?