@@ -27,7 +27,8 @@ so we're targeting filter material able to block particles with minimum ~0.25um
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@@ -27,7 +27,8 @@ so we're targeting filter material able to block particles with minimum ~0.25um
- CMAD: count median aerodynamic diameter
- CMAD: count median aerodynamic diameter
### conventional test methods
## Filtration efficiency tests
### biological challenge particles
- Henderson apparatus: generates closed circuit microbial aerosols from a Collison nebulizer at a controlled humidity
- Henderson apparatus: generates closed circuit microbial aerosols from a Collison nebulizer at a controlled humidity
- Collison nebulizer - generally a pneumatic atomizer [^collisonNebulizer]
- Collison nebulizer - generally a pneumatic atomizer [^collisonNebulizer]
- 
- 
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@@ -36,9 +37,24 @@ so we're targeting filter material able to block particles with minimum ~0.25um
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@@ -36,9 +37,24 @@ so we're targeting filter material able to block particles with minimum ~0.25um
- Bacillus atrophaeus : 0.95-1.25um, 10^7 cfu in challenge [^DIYmask]
- Bacillus atrophaeus : 0.95-1.25um, 10^7 cfu in challenge [^DIYmask]
- Bacteriophage MS2 MCIMB10108: single strange RNA ~20nm diameter, 10^9 pfu in challenge [^DIYmask]
- Bacteriophage MS2 MCIMB10108: single strange RNA ~20nm diameter, 10^9 pfu in challenge [^DIYmask]
- E. Coli phi174 [^VFEreport]
- E. Coli phi174 [^VFEreport]
- Viable particle cascade impactor (andersen sampler) for collecting particles, incubating them for a day or two, then counting bacteria or phage growth
performance difference between pleated hydrophobic filters and electrostatic filters??
performance difference between pleated hydrophobic filters and electrostatic filters??
### non-biological challenge particles
- send colliodal spheres through atomizer (what's the diff between nebulizer and atomizer?) and use optical particel counter (OPC) to determine filtration efficiency
- ASTM standards uses latex spheres. could potentially use gold particles
- charge neutralizer recommended - but Lorena said viruses are typically polarized so maybe charge neutralization could be ignored initially
## shopping list
- nebulizer for aerosolization [^nebulizer_selection]
- three-jet Collison nebulizer?
- impinger for collection
- wet and dry thermometer / hygrometer for humidity
- andersen sampler?? could be nice to bin different size particles - six-stage viable particle cascade impactor
### Resources
### Resources
[^DIYmask]:University of Cambridge [DIY mask efficacy testing](https://www.researchgate.net/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic)
[^DIYmask]:University of Cambridge [DIY mask efficacy testing](https://www.researchgate.net/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic)
[^filterPerformance]:AR Wilkes [The bacterial and viral filtration performance of breathing system filters](https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2044.2000.01327.x)
[^filterPerformance]:AR Wilkes [The bacterial and viral filtration performance of breathing system filters](https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2044.2000.01327.x)
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@@ -49,13 +65,3 @@ performance difference between pleated hydrophobic filters and electrostatic fil
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@@ -49,13 +65,3 @@ performance difference between pleated hydrophobic filters and electrostatic fil
[^VFEreport]:[Nelson Laboratories: Viral Filtration Efficiency (VFE) at increased challenge level](https://gitlab.cba.mit.edu/pub/coronavirus/tracking/uploads/164d119b5a7a5751c685a6677378668a/ER_2235600_Attachment_5_Viral_Filtration_Efficiency.pdf)
[^VFEreport]:[Nelson Laboratories: Viral Filtration Efficiency (VFE) at increased challenge level](https://gitlab.cba.mit.edu/pub/coronavirus/tracking/uploads/164d119b5a7a5751c685a6677378668a/ER_2235600_Attachment_5_Viral_Filtration_Efficiency.pdf)
[^nebulizer_selection]:[Nebulizer selection from CH tech](http://chtechusa.com/Manuals/Selecting%20the%20Model%20and%20Configuration%20Instructions.pdf)
[^nebulizer_selection]:[Nebulizer selection from CH tech](http://chtechusa.com/Manuals/Selecting%20the%20Model%20and%20Configuration%20Instructions.pdf)
## needed for testing apparatus
- nebulizer for aerosolization [^nebulizer_selection]
- three-jet Collison nebulizer?
- impinger for collection
- wet and dry thermometer / hygrometer for humidity
- andersen sampler?? could be nice to bin different size particles - six-stage viable particle cascade impactor
