Spread the word, but perhaps there is a certain avoidance of FaceBook and other attempts to let a data-mining company shoulder the burden of hosting a comment site.
For example, a local newspaper recently decided to shut down it's web site for comments, shifting entirely to facebook and twitter and others for comments.
That essentially cut out those of us with paid subscriptions to the paper who have weighed the risks and dangers of facebook with the convenience.
There are enormous helpful services that they dangle in front of users, especially for family who has spread across the world and yet all this free stuff comes with a price.
I, for one, think that having the forum exist on facebook excludes many who would otherwise participate but cannot since they choose not to be a facebook user.
I like forums like this one, for my two cents worth.
Just commenting, but I think your effort to get the Purple Air community talking and exchanging ideas and experiences is great. I'm hoping to add that to my set up this summer.
Dale