EVALUATION OF SEVERAL AIR CLEANERS FOR REDUCING INDOOR RADON PROGENY

Over the past several years, studies have been made of the effectivene ss of several kinds of air cleaners in removing radon decay products f rom indoor air using a recently developed automated, semi-continuous m easurement system that can determine the activity-weighted size distri butions in occupied homes. Measurements of activity-weighted size dist ributions and radon concentrations were made every 90 min in a home wi th a high air exchange rate. A week-long series of measurements was ma de for the home with no cleaner operating and a similar set of measure ments were made for each of the air cleaners. Two different types of a ir cleaners were tested in this study; filtration units (two different designs from two different manufacturers) and two ion generator/fan s ystems (identical design NO-RAD systems, but from two different manufa cturers). From the measured distributions and a dosimetric model, the effect of the air cleaners on the dose to lung can be estimated. It wa s found that the filtration units resulted in a median reduction in ex posure of 15% and 36% for the two units and corresponding dose reducti ons of 32% and 53%. The two NO-RAD systems produced 37% and 10% reduct ions in the median exposure, but the reductions in the median dose wer e 49% and 46%. Examination of the components of the NO-RAD system oper ating separately resulted in the fan causing a small dose reduction an d the ionizer producing a small dose increase. However, very few size distributions were measured for these separate component studies and a more detailed study of the separate effects of the NO-RAD components is needed.