$(20$ points $-$ Indoor Air$)$ A single$-$story home with air exchange rate of $0\mathrm{.}8$ ach has $250m^2$ of floor

space and a total volume of $500m^3.$ If $1pC\frac{i}{m^2}*s$ of radon is emitted from the soil and enters the

house,

a$.$ Estimate the steady$-$state indoor radon concentration $(pC\frac{i}{L}.$ Should this home take

measures to lower the radon concentration, given that the action threshold is $4pC\frac{i}{L}?$

The decay constant for radon is $7\mathrm{.}6{10}^{-3}h{r}^{-1}.$

b$.$ If the radon concentration was above the action threshold, how should the residents

adjust the air exchange rate to reduce the concentration to acceptable levels? $($i$.$e$.$ What

air exchange rate would be needed $($air changes$/$hr$)?)$