I knew I had encountered a list of filtration efficiencies for a number of materials. The point was that in a contamination episode, you had access to any number of improvised filters that were better than nothing. I finally found a book of the handouts for my Physics 468-B class decades ago, and lo and behold!
Respiratory protection provided by common household and personal items against aerosols of 1 to 5 µ particle size
|Item||# of thicknesses||Resistance: mm H2O||# of Observations||Efficiency, Geometric mean||99% confidence, lower||99% confidence, upper|
|Handkerchief, man’s cotton||16||36||32||94.2||92.63||95.5|
|Handkerchief, man’s cotton||8||18||32||88.9||85.5||91.6|
|Handkerchief, man’s cotton||crumpled||—||32||88.1||85.1||90.5|
|Bath towel, Turkish||2||11||32||85.1||83.3||86.8|
|Bath towel, Turkish||1||5||30||73.9||70.7||78.8|
|Bed sheet, muslin||1||22||32||72||68.8||74.9|
|Bath towel, Turkish||1 (wet)||3||31||70.2||68||72.3|
|Shirt, cotton||1 (wet)||>150 (a)||15||65.9||57.9||72.3|
|Handkerchief, woman’s cotton||4 (wet)||84 (a)||32||63||57.3||58.7|
|Handkerchief, man’s cotton||1 (wet)||98 (a)||30||62.6||57||67.5|
|Dress material, cotton||1 (wet)||180 (a)||31||56.3||49.6||62|
|Handkerchief, woman’s cotton||4 (wet)||2||32||55.5||52.2||58.7|
|Dress material, cotton||1||5||31||47.6||41.4||53.2|
|Handkerchief, man’s cotton||1||2||32||27.5||22||32.5|
(a) Resistance obtained when checked immediately after hand wringing. This resistance began to decrease after about one minute when the material started to dry.
I’m not sure of the original source. It may be an old version of an OSSHA handbook.