The impact and effectiveness of the general public wearing masks to reduce the spread of pandemics in the UK: a multidisciplinary comparison of single-use masks versus reusable face masks.

Reply to Reviewers Comments

Beatrice Smyth

The paper is much improved on the previous version.  The flow of the paper is much better and the content more cohesive.  I just have a few minor suggestions:

1. In the abstract, it is noted that 124,000 tonnes of waste would be created and 66,000 tonnes would be unrecyclable contaminated plastic waste.  Is the remainder recyclable uncontaminated waste?  Please can you explain what this portion is composed of.

We expanded the sentence to clarify the composition of plastic waste, as follows:

"If every person in the UK uses one single-use mask each day for a year, it will create a total waste of 124,000 tonnes, 66,000 tonnes of which would be unrecyclable contaminated plastic waste (the masks), the rest being recyclable packaging typically used for transportation and distribution of masks."

2. The text in the section on European Standards refers to ‘community face masks’ and ‘Community Face Coverings’.  Table 1 refers to ‘Community Masks’.  Are these the same thing?  Could you please clarify?  It would also be useful to explain what is meant by community mask.

These are all the same have amended the text to use the standard term ‘Community Face Covering’. We state that a Community Mask is one that complies with guidelines set out in CWA 17553:2020.

3. The footnote in Table 1 isn’t clear, particularly from ‘but these masks…’ onwards.  Please rephrase.

We have amended this to make it clearer.

4. What are the ‘wash bags’ referred to in the section on Materials and their Filtration Efficiency?

We have now explained this term in the text.

5. In the Cost Comparison Section under Disposal, the text refers to the weight of a single-use mask.  Strictly speaking, this is mass.

We have corrected this in the text.

6. Is there a better way to present the information in Figure 3?  The washing and disposal categories are difficult to make out on the graph.

We have changed the original figure from a bar chart comparison to a pie chart comparison and added the percentage breakdown of the cost categories.

7. Could you please check the data in Figure 4?  The Republic of Ireland is highlighted in yellow, but I don’t think this is the case.  It’s also not clear what is meant by ‘yellow indicates countries where mandatory mask use is imposed on part of the country only but their use is recommended by government’.  Do you mean that their use country-wide is recommended but not mandated by government?

We rephrased the figure caption to “Yellow indicates countries where mask use was mandated by law in parts of the country and governmentally recommended in other parts.”

8. There is a sentence in the Discussion and Conclusions section that states that ‘anecdotal evidence in the UK suggests that very few people wear their reusable masks every day’.  It’s not clear what this sentence is meant to tell us and I suggest deleting it.  People mightn’t wear their reusable mask every day for a variety of reasons, like not going anywhere that requires mask use or wearing a disposable mask instead.  It doesn’t necessarily mean that they’re not following the guidelines.

We have removed that phrase.

9. Further on in the discussion, the text states that ‘governments may consider stockpiling masks…’.  Is this referring to single-use masks?  In the last paragraph, the text uses the phrase ‘capacity capable’ – is this the correct phrase?

We have clarified these phrases.

10. There are a few minor grammatical errors throughout the paper.  Please give the paper one final proof-read

We have completed a final proof-read and made minor grammatical error corrections.

Other corrections: updated colouring of Tables A11 and A13; references updated.

Due to the COVID-19 pandemic, the UK government has mandated the use of face masks in various public settings and recommends the use of reusable masks to combat shortages of medically graded single-use masks in healthcare. To assist decision-making on the choice of masks for future pandemics, where shortages may not be a contributing factor, the UCL Plastic Waste Innovation Hub has carried out a multidisciplinary comparison between single-use and reusable masks based on their anatomy, standalone effectiveness, behavioural considerations, environmental impacts and costs.

Although current single-use masks have a higher standalone effectiveness against bacteria and viruses, studies show that reusable masks have adequate performance in slowing infection rates of respiratory viruses. Material Flow Analysis, Life Cycle Assessment and cost comparison show that reusable masks have a lower environmental and economic impact than single-use masks. If every person in the UK uses one single-use mask each day for a year, it will create a total of 124,000 tonnes of waste, 66,000 tonnes of which would be unrecyclable contaminated plastic waste (the masks), with the rest being the recyclable packaging typically used for transportation and distribution of masks.Using reusable masks creates >85% less waste, generates 3.5 times lower impact on climate change and incurs 3.7 times lower costs.

Further behavioural research is necessary to understand the extent and current practices of mask use; and how these practices affect mask effectiveness in reducing infection rates. Wearing single-use masks may be preferred over reusable masks due to perceptions of increased hygiene and convenience. Understanding behaviour towards the regular machine-washing of reusable masks for their effective reuse is key to maximise their public health benefits and minimise environmental and economic costs.