A stack emitting $64$ x $106$g of SO$2$ per second has an effective stack height of $150$ m$.$ The windspeed is $2\mathrm{.}5$ m$/$s at $10$ m$,$ and. The wind speed exponent p is $0\mathrm{.}15$ Estimate the ground$-$level SO$2$ concentration for the following: a$)$ Directly downwind at a distance of $1\mathrm{.}5$ km $($oy $=224$ m oz $=171$ m$).$ b$)$ At a point located $1\mathrm{.}5$ km downwind and $200$ m off the downwind axis $($Gy$=224$ m oz $=171$ m$)$