A power plant measures its emissions by putting a sensor 1 mile upwind (in the opposite direction of the wind) of the plants smokestack. Will the reading this sensor provides be a random sample of the plants emissions?

The reading that the sensor will provide will be random samples of the different plant emissions. This is because 1 mile is quite a long distance already, if samples are to be tested that far, it is not guaranteed that the samples are really what they are to be.