The S$.$ Stinky Company operates a factory in the center of a roughly circular area of property of $500m$ radius $($see sketch$).$ The air pollution district wants to put fence$-$line monitors right at the property boundary in all directions such that they can detect cmissions of $1k\frac{g}{d}$ of toxic materials or greater. If releases are presumed to occur at $10m$ elevation $($neglect any plume rise effects$)$ at a wind speed is $2\mathrm{.}5\frac{m}{s},$ during daytime with slight solar radiations, what should the detection level of sensors be to make such a measurement?