The Public Lab Providence office has just setup our first PurpleAir. Below is a screenshot of the map. Checkout the fully interactive map here.
@zengirl2 The PurpleAir folks say that the sensor come "factory calibrated." I am certainly skeptical of that because its been shown that humidity can affect readings. The device does include a humidity sensor but it is unclear if they are using that data to post-calibrate the readings or not.
But another thing to consider when comparing the "official" numbers to the PurpleAir, at least in RI, there are only 2 federal monitors measuring PM in the city. It is very likely, in my opinion, that there could be an area that there network is not adequately capturing with their forecasts.