Mask Effectivness for .06 micron particle?

[thehappyscientist]

Hi everyone,

I am very concerned about the effectivness of N95 masks for health workers.

The current literature reflects that SARS-COV2 particle size can be from 60-140nm (.06 to .14 micron)

However, OSHA states particle respirators and filters (e.g., N95 and N100) are “all” tested at the same particle size, 0.3 microns, a much, much, larger particle.

So where is the data showing effectivity of N95 and N100 on the significantly smaller SARs-COV2 sized particle?

Reported median of 67 nm (.067 micron): SD 15 nm, median 65 nm, 95% CI 41–102; n=33). Varga Z, Flammer AJ, Steiger P, et al. Electron microscopy of SARS-CoV-2: a challenging task - Authors' reply. Lancet. 2020;395(10238):e100. doi:10.1016/S0140-6736(20)31185-5

Reported ~60-140nm (as low as .06 micron): Zhu N, Zhang D, Wang W, et al. A Novel Coronavirus from Patients with Pneumonia in China, 2019. N Engl J Med. 2020;382(8):727-733. doi:10.1056/NEJMoa2001017

Reported 70-110 nm (as low as .07 micron): Menter T, Haslbauer JD, Nienhold R, et al. Post-mortem examination of COVID19 patients reveals diffuse alveolar damage with severe capillary congestion and variegated findings of lungs and other organs suggesting vascular dysfunction [published online ahead of print, 2020 May 4]. Histopathology. 2020;10.1111/his.14134. doi:10.1111/his.14134

As a side note,  SARS-COV1 was reported even smaller 50-80nm

Goldsmith CS, Tatti KM, Ksiazek TG, et al. Ultrastructural characterization of SARS coronavirus. Emerg Infect Dis. 2004;10(2):320-326. doi:10.3201/eid1002.030913

Goldsmith CS, Miller SE. Modern uses of electron microscopy for detection of viruses. Clin Microbiol Rev. 2009;22(4):552-563. doi:10.1128/CMR.00027-09

Shieh WJ, Hsiao CH, Paddock CD, et al. Immunohistochemical, in situ hybridization, and ultrastructural localization of SARS-associated coronavirus in lung of a fatal case of severe acute respiratory syndrome in Taiwan. Hum Pathol. 2005;36(3):303-309. doi:10.1016/j.humpath.2004.11.006

Qinfen Z, Jinming C, Xiaojun H, et al. The life cycle of SARS coronavirus in Vero E6 cells. J Med Virol. 2004;73(3):332-337. doi:10.1002/jmv.20095