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    Review of 'The environmental dangers of employing single-use face masks as part of a COVID-19 exit strategy'

    The environmental dangers of employing single-use face masks as part of a COVID-19 exit strategyCrossref
    The promising title is misleading; the paper is flawed and already out-of-date.
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        Rated 2 of 5.
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        Rated 2 of 5.
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        Rated 2 of 5.
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        Rated 2 of 5.
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        Rated 2 of 5.
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    The environmental dangers of employing single-use face masks as part of a COVID-19 exit strategy

    - As the UK government defines its lockdown exit strategy, the mandatory wearing of masks in public is likely to be considered. - The World Health Organisation (WHO) does not currently recommend the use of masks by general populations as a means of preventing the spread of COVID-19, although a growing number of countries have been adopting this precautionary measure. - The NHS states that there needs to be clear evidence that wearing masks will deliver significant benefits to take the UK out of lockdown, if it is to jeopardise mask supply. - There is a growing body of evidence to suggest that even basic face masks can be effective in reducing the spread of the virus, by reducing the range and volume of exhaled water droplets containing SARS-CoV-2. - Most masks available for sale are made from layers of plastics and are designed to be single-use. If every person in the UK used one single-use mask each day for a year, that would create 66,000 tonnes of contaminated plastic waste and create ten times more climate change impact than using reusable masks. - In a hospital environment, single-use protective wear such as masks and gloves are contaminated items, and there are systems in place for their safe disposal, which involve segregation and incineration. - No such segregated system exists for the general public, and a policy that makes wearing face masks mandatory will result in thousands of tonnes of contaminated waste deposited in the street and in the household waste. - Evidence suggests that reusable masks perform most of the tasks of single-use masks without the associated waste stream. - An extensive public health campaign with clear instructions about how to wear, remove, and wash reusable masks will be needed if this is to become part of the UK governments exit strategy.

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      Review text

      This paper highlights the dangers of trying to rush something into print without prior peer review because the subject is topical. Unfortunately, it is seriously flawed and already out-of-date.

      Its title plainly states it is about “the environmental dangers of single use masks”. As this was not something I had read about before, it provoked my interest. I was disappointed to discover that the title is seriously misleading.  The main text runs to about 11 pages, but only 25% of it relates to a comparison of the environmental impacts of single use and reusable masks. The rest covers: the type and anatomy of masks; their effectiveness; the role of mask-wearing; and behaviour change considerations for reusable mask use. The main findings of the environmental impact study are not even included in the abstract or the conclusions.

      A more appropriate title would therefore be something like:

      “A comparison of the use by the general public of single-use or re-usable face masks: effectiveness, availability, environmental impact and behaviour considerations.”

      That the paper has ended up being so different from what the title promises seems to be because it was written by a committee. As the acknowledgements indicate, each section was written by a different pair or trio of people. Perhaps it was felt important that each were given their “fair share” of the manuscript, even if it wasn’t strictly relevant to the aim and title of the paper.

      The Conclusions are written by someone else entirely. They refer to “reusable PPE mask(s)” seven times, whereas the phrase doesn’t appear once in the rest of the text!  This author seems to have forgotten that the paper was supposed to be about “the environmental danger of single-use masks”.   (S)he does not even refer to the results of the study of the environmental impact that their colleagues conducted or their conclusions. (S)he also include the sentence: “If washing items that are likely to cause illness (high-risk), the NHS recommends that they should be washed at 60°C with a bleach-based product.”  No-where else in the text is a “bleach-based” product mentioned. The manual wash assumptions used in the study were “detergent in mildly warm water”. The machine wash assumptions were for “detergent” and 40°C. And, as anyone familiar with washing with bleach will know, it can have a disastrous effect on coloured fabrics!

      What about the environmental impact assessment itself?  Although the paper was published on May 3 2020, it is already out of date. In the introduction, they state: “The aim of this paper is to examine the environmental impact of the UK adopting masks for the general population in particular the amount of contaminated plastic waste produced.”  Later in the paper it states: “Within the UK, the use of face masks has not yet been identified as a behavioural strategy for reducing the transmission of COVID-19 among the general population.” The UK government has now made it clear they are strongly recommending people wear “face-coverings” when on public transport or in shops, or in other situations such as work where social distancing cannot be maintained. They have made it clear that these should preferably be re-usable and definitely not medical grade.  I have never heard or seen any reference in government guidance to a recommendation that a disposable filter should be used in the reusable mask.

      Consequently, Scenarios 1, 3 and 5 are not going to happen. Scenario 1, with every person wearing a mask every day, did seem rather unrealistic, given that many people don’t go out every day and it is recommended that young children don’t wear masks. The assertion that “this would create over 124,000 tonnes of unrecyclable plastic waste (66,000 tonnes of contaminated waste and 57,000 tonnes of plastic packaging” could thus be exaggerated, even if Scenario 1 was going to happen.

      The washing assumptions in Scenarios 2 and 3 also seem unrealistic, involving large amounts of hot water per mask. As the Government has been saying for months, washing your hands thoroughly with soap and water is very effective at killing the virus (because it breaks down the virion’s outer lipid layer.) The same should apply to re-usable masks – a quick scrub with soap or detergent in warm water, a thorough rinse with cold water and then leave to dry.

      The presentation of the results could be improved. For example, in Table 2 the Units are not explained. Figure 1 is very difficult to fully understand with so many different categories in stacked columns. It does seem odd that the  CO2  equivalent  of “Mask Use”  is so much greater for manual wash than machine wash. The category might better be “Mask wash” and perhaps the difference is down to the assumptions about the manual washing assumptions I questioned above.

      Nevertheless, by the authors’ reckoning, machine washed re-usable masks without filters are by far the most environmental-friendly form of mask wearing by the general public. This seems to be the key novel and useful finding in the paper, but it is not mentioned in the abstract or the conclusions.  Amazing!

      There are many other smaller details in the paper that careful editing would have improved.

      For example, on page 8 there are the sentences:

      “The use of masks may give users a false sense of protection, thus encouraging risk-taking.

      No mask protects against the transmission of a virus through direct contact, and hand washing is essential prior to using, and after removing it.”

      The same sentences appear in the next section. (Did one team cut and paste from the other?)

      In page 10 it states: “Considering that the half-life of the virus is 5.6 hours”. This is not referenced, but it is clear that virus viability varies greatly according to the medium it is in or on, temperature, exposure to sunlight etc.

      I think these are signs of the haste with which the authors rushed to get the paper into print, without careful consideration of every word.



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