=+4-28.

A maximum of 10 smokers are anticipated in a smoking room and cach is expected to con-

tribute about 150 ug/min of environmental tobacco smoke (ETS) to the space. It is desired to hold the particulate level of ETS below 180 g/m' using filters with an effective efficiency of 80 percent and an intake of outdoor air at the rate of 20 cfm per person. Assuming a ventila-

tion effectiveness of 0.85 and the filter located downstream of the mixed recirculated and out.

door air, determine the required rate of supply air to the room.