Table 1. Comparison of impinger and PTFE filter efficiencies for culturable virus and viral RNA.
Sample Source: impinger | Filter | Filter | Ratiod | |
Aerosol timea | FFU/collectionb | FFU/collectionc | GEq RNA/collection | FFU∶RNA |
10 min | 4.9 (0–19.6) E+03 | 4.9 (0.2–12.5) E+03 | 2.0 (0.9–3.9) E+06 | 1∶411 |
20 min | 16.2 (0–28.5) E+03 | 12.2 (5.0–25.0) E+03 | 4.2 (2.3–7.6) E+06 | 1∶344 |
30 min | 35.7 (19.5–49.3) E+03 | 4.0 (3.0–5.5) E+03 | 6.8 (4.1–9.1) E+06 | 1∶1705 |
Virus 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.
Impinger 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.
PTFE 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.
Ratio of group means of FFU and GEq RNA collected respectively.