![]() That is, small increases in temperature cause large increases in the death rate. Extensive research has confirmed that at least for living cells, the sensitivity of thermal destruction is very strongly linked to temperature. At these levels, we expect the viral concentration to be lowered by log 5‐7, near or below the detectable limit.īecause of the seriousness of the current coronavirus infection, we suggest a reasonable safety factor can be obtained by increasing the above‐listed temperatures by 10☌ (about 18 ☏). However, for temperatures in the range 50‐55☌ (122‐131☏) we recommend 20 minutes or longer of exposure. ![]() For temperatures between 55 and 60☌ (131‐140☏) heating should last 5 minutes or more. For temperatures above 65☌ (149☏) is expected to cause near complete inactivation with exposures greater than 3 minutes. We provide a reasonable estimate for near complete thermal destruction of coronavirus. Recommendations for thermally destroying coronavirus Rather, our intent is to provide a single thermal recommendation that can be used to sterilize a broad range of materials.ġ.2. With this acknowledged, we opt to not provide separate analysis for different strains or media. For instance, media with protein content make the virus more resistant to heating. It is further known that the media can affect the viral survival. We also acknowledge that there are different thermal sensitivities for differing strains. We note that there are differences in the strains and media in which the virus was cultivated. In Table Table1, 1, we present this literature information. Of course, the actual log reduction would be based on the sensitivity of the measurement instruments however, for practical purposes, we consider a viral reduction of 7 or greater to be at or near total sterilization. We have substituted an equivalent log reduction of 7 for these cases. In some studies, the heating protocol was such that no viral presence was detected afterwards. In the listing, we report log reductions in viral load obtained from the references. In the following, a list of temperature/duration/inactivation rates is provided for coronavirus pathogens. The necessary temperature would also be based on the materials of the surface, the environment, etc.”.īut despite official statements such as the above, there is, in fact, some literature on the temperature and exposure durations that are required to inactivate SARS‐CoV‐2. However, we don't have direct data for this virus, nor do we have direct data for a temperature‐based cutoff for inactivation at this point. “Generally coronaviruses survive for shorter periods at higher temperatures and higher humidity than in cooler or dryer environments. The summary is used to provide a reasonable recommendation for users to thermally destroy viruses on masks, clothing, or other objects.Īn example of the state of knowledge on temperatures and coronavirus survival is provided by the CDC, which states: Here, we summarize all the existing temperature/duration information for both SARS‐CoV‐2 and its sensitivity to heat. Similarly, there is no current advice available for the use of heat to destroy SARS‐CoV‐2. Mask users can apply sanitizing chemicals (such as alcohol) but it is not clear whether this type of sanitizing would adversely affect the porous structure of masks and thereby make them less effective over time. For instance, woven fibers differ from non‐woven polymeric filter media. But to our best knowledge, there is no scientific study on the required duration, and any required duration would depend on the materials that form the mask. That is, contaminated masks can be treated by merely setting them aside for some required duration until the viruses die. It is reasonable to expect a similar survival duration for viruses on/in protective face masks. The general consensus is that viruses can survive up to a few days in clothing. Some clothing types, for instance, are very capable of retaining moisture and consequently, this affects the survival of virus contained therein. However, the required durations are not known absolutely, and certainly depend on the type of surface. How should masks, clothing, and other items be treated? In many instances, simply setting items aside for a long enough period of time will kill the virus. Upon returning to isolation, masks and other clothing should be treated as contaminated with virus. When people venture into public, they are often donning masks (homemade or industrially produced) or other protective clothing. As societies put themselves into voluntary or enforced isolation, large populations of people are experiencing reduced contact with others in public.
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