Initial concentrations of chlorine gas (2-12 p.p.m.) were measured on FFRs wet with bleach immediately following submersion for 30 min (Fig. 3) . FFRs that were treated using bleach and allowed to air-dry overnight (as described in Table 1 ) had initial concentrations of $0.05 p.p.m. followed by no detectable off-gassing (0 p.p.m.) after the initial data point. FFRs which were submerged in bleach, immediately rinsed (entirely under a stream of deionized water for $1 min) and then allowed to air-dry overnight had concentrations similar to FFRs which were not rinsed, indicating that the water rinse had no effect. When FFRs were rehydrated by rinsing with deionized water following overnight air-drying, low-level chlorine off-gassing concentrations were measured at $0.1 p.p.m. (Fig. 4) . 