Comparison of impinger and PTFE filter efficiencies for culturable virus and viral RNA.

aVirus NC99 was nebulized in 6 experiments with impinger alone and 9 experiments with impinger and PTFE filter collections in parallel. The mean (range) total dose nebulized was 1.8 (1.1–2.2)×107 FFU, calculated by virus concentration in Collison at beginning of aerosol generation times fluid volume nebulized for each run.bImpinger collection measured for 5.4 (range 5.3–5.5) L/min, reported as total FFU collected during interval of nebulization. N = 5 at each time point as one outlier value was removed from each group.cPTFE filter collection combines two filters in parallel for total flow of 4.0 L/min, reported as total FFU and total genome equivalents (GEq) of RNA measured by T5000 assay.dRatio of group means of FFU and GEq RNA collected respectively.