key: cord-0868451-j66nkbyt
authors: Liu, Yuangang; Leachman, Sancy A.; Bar, Anna
title: Reply to Notes and Comments on “Proposed Approach 1 for Re-using Surgical Masks in COVID-19 Pandemic”
date: 2020-05-22
journal: J Am Acad Dermatol
DOI: 10.1016/j.jaad.2020.05.084
sha: 9f8d24145b4a12f6816370fe05c801faa56edfc2
doc_id: 868451
cord_uid: j66nkbyt

nan

Further, the best method of decontamination, if the need arises, will vary at different institutions where a variety of equipment may (or may not) exist.

Our paper offers a simple solution -a low-cost, ubiquitously available method that does not require special equipment 3 . We would like to clarify that the dry heating condition recommended in our paper is 65-70 o C but not 100 o C 3 . The selection of this condition is based on the facts that 1) coronavirus is effectively inactivated at 65 o C or above for 30 minutes 4 , and 2) dry heating at 70 o C or below has minimal effect on the deformation of meltblown polypropylene which comprises the mask filtration material 5 . Due to this limited temperature range, we recommend using a heating apparatus with a temperature adjusting feature such as an oven, incubator, or blanket warmer. A microwave oven is not recommended because there are metal parts in the face mask, the effects on the filter are unknown, and the temperature is not tunable.

So far, there is no experimental data to compare the effect of dry heating vs UV irradiation on inactivation of SARS-CoV-2. A study by Kariwa et al showed that the infectivity of SARS-CoV was abolished by dry heating at 56 o C for 60 min whereas residual infectivity of SARS-CoV was still detected with UV irradiation of 134 µW/cm 2 for 60 min 4 . This suggests that SARS-CoV is relatively resistant to UV irradiation. Despite the survival of residual SARS-CoV, the UV irradiation achieved more than 5 log reduction of SARS-CoV (3.8 x 10 7 to 1.8 x 10 2 ). Therefore, UV irradiation still considered as an effective approach for decontamination of coronavirus.

In sum, it is our hope that our article is not seen as a criticism of alternative methods that others are using to reduce exposures in PPE-limited environments; our goal was to pass on a reliable, simple, and cost-effective method that would be available to anyone in need.

Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic

A method to determine the available UV-C dose for the decontamination of filtering facepiece respirators

Proposed approach for reusing surgical masks in COVID-19 pandemic

Inactivation of SARS coronavirus by means of povidoneiodine, physical conditions and chemical reagents

EFFECT OF TEMPERATURE ON THE STRUCTURE AND FILTRATION PERFORMANCE OF POLYPROPYLENE MELT-BLOWN NONWOVENS