INDOOR OUTDOOR CONCENTRATIONS AND CORRELATIONS OF PM10-ASSOCIATED MUTAGENIC ACTIVITY IN NONSMOKERS AND ASTHMATICS HOMES

The indoor-outdoor relations of mutagenic compounds associated with airborne particles less than 10-mum aerodynamic diameter (PMIO) were studied in the homes of 10 nonsmokers located in southern California. Asthmatics lived in nine of the 10 homes studied. Low-volume samplers (4 and 2 L/min) fitted with PM10 and cyclone (5-mum nominal particle size cut) particle preselectros were used to collect 24-h air samples indoors and outdoors. In addition, three individuals carried personal samplers for 24-h periods. Filter extracts were tested for mutagenicity using a sensitive Salmonella microsuspension assay. The concentrations of particle-associated mutagens were significantly higher outdoors compared to indoors. For the PM10- and cyclone-collected samples, indoor-outdoor ratios averaged 0.46 and 0.49, respectively. There were significant correlations between indoor and outdoor mutagenicity (revertants/m3) for all samples (Spearman rank, R(s) = 0.74; n = 25 pairs; p < 0.001). Further, the indoor and outdoor correlation of specific-mass mutagenic activity [revertants per unit particle mass (revertants/mug)] was highly significant [p < 0.001; R(s) = 0.90 (n = 25 pairs)]. The mutagenic activity of personal samples was very similar to the fixed-site samples collected indoors. The results support the hypothesis that mutagen composition of the indoor and outdoor particles are similar and that outdoor particles which infiltrate into homes may be a significant source of respirable mutagenic particles in the homes of nonsmokers.