Consider a house into which radon is emitted through cracks in the basement. The total volume of the house is 650 m^3 (assume that the volume is well mixed throughout). The radon source emits 250 pCi/s (A picoCurie [pCi] is a unit proportional to the amount of radon gas and indicates the amount of radioactivity of the gas). Air inflow and outflow can be modeled as a flow of clean air into the house of 722 m^3 /h and an equal air flow out. Radon can be considered to be conservative in this problem. Required:
a. What is the retention time of the house?
b. What is the steady-state concentration of radon in the house (units of pCi/L)?