Multiple Sensors in different locations give the same results

I have been looking at the data from a number of sensors placed around the city of Salisbury some urban others suburban. They have all been calibrated against each other and all give exactly the same values when their calibration factors are applied. I am wondering what conclusions to draw from this?

Probably that there are no sources of emissions in close proximity to the sensors. Other than that, not sure.

Thank you. I think that is the only conclusion to draw. I was expecting some variation but then perhaps other factors far outweigh the local ones.