Why are the air quality measurement devices located on the roof (pictures in tge article)? Fresh air is up there, but what people breathe is air closer to the surface.
A better question might be why they are measuring temperature there on a hot roof and not over grass. According to NOAA, that's a Class 5 location (the worst):
Class 5 (error ≥ 5ºC) – Temperature sensor located next to/above an artificial heating source, such a building, roof top, parking lot, or concrete surface. (Section 2.2.1 of the U. S. Climate Reference Network Site Information Handbook)
http://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/progr...
But I’m sure they aren’t using it as a calibrated value (obviously they would have guidelines for placement and would know this doesn’t meet them), it’s probably just being used as an indicative reading.