Question: When should a face mask be worn?

Answer passage (source: UK):
page_title: Guidance Safe working in education, childcare and children’s social care settings, including the use of personal protective equipment (PPE)
section_headers: How to work safely in specific situations, including where PPE may be required
section_content: Reference to PPE in the following situations means:

fluid-resistant surgical face masks
disposable gloves
disposable plastic aprons
eye protection (for example a face visor or goggles)

Where PPE is recommended, this means that:

a facemask should be worn if a distance of 2 metres cannot be maintained from someone with symptoms of coronavirus
if contact is necessary, then gloves, an apron and a facemask should be worn
if a risk assessment determines that there is a risk of fluids entering the eye from, for example, coughing, spitting or vomiting, then eye protection should also be worn

When PPE is used, it is essential that it is used properly. This includes
scrupulous hand hygiene and following guidance on how to put PPE on and take
it off safely in order to
reduce self-contamination.
Face masks must:

cover both nose and mouth
not be allowed to dangle around the neck
not be touched once put on, except when carefully removed before disposal
be changed when they become moist or damaged
be worn once and then discarded - hands must be cleaned after disposal

*[PPE]: personal protective equipment

Reviewer feedback on this answer:
Provides detailed guidance about when face masks should be worn. Appropriate and on topic.
The response covers the use of all PPE; when, where, how, and why. It also covers how to properly wear and use the PPE. Great amount of useful information.

Reviewer ratings:
Excellent
Excellent

Answer passage (source: UK):
page_title: Construction and other outdoor work
section_headers: 6. Personal protective equipment (PPE) and face coverings
6.1 Face coverings
section_content: There are some circumstances when wearing a face covering may be marginally
beneficial as a precautionary measure. The evidence suggests that wearing a
face covering does not protect you, but it may protect others if you are
infected but have not developed symptoms.
A face covering can be very simple and may be worn in enclosed spaces where
social distancing isn’t possible. It just needs to cover your mouth and nose.
It is not the same as a face mask, such as the surgical masks or respirators
used by health and care workers. Similarly, face coverings are not the same as
the PPE used to manage risks like dust and spray in an industrial context.
Supplies of PPE, including face masks, must continue to be reserved for those
who need them to protect against risks in their workplace, such as health and
care workers, and those in industrial settings like those exposed to dust
hazards.
It is important to know that the evidence of the benefit of using a face
covering to protect others is weak and the effect is likely to be small,
therefore face coverings are not a replacement for the other ways of managing
risk, including minimising time spent in contact, using fixed teams and
partnering for close-up work, and increasing hand and surface washing. These
other measures remain the best ways of managing risk in the workplace and
government would therefore not expect to see employers relying on face
coverings as risk management for the purpose of their health and safety
assessments.
Wearing a face covering is optional and is not required by law, including in
the workplace. If you choose to wear one, it is important to use face
coverings properly and wash your hands before putting them on and taking them
off. You should be prepared to remove your face covering if asked to do so by
police officers and staff for the purposes of identification.
Employers should support their workers in using face coverings safely if they
choose to wear one. This means telling workers:

wash your hands thoroughly with soap and water for 20 seconds or use hand sanitiser before putting a face covering on, and after removing it
when wearing a face covering, avoid touching your face or face covering, as you could contaminate them with germs from your hands
change your face covering if it becomes damp or if you’ve touched it
continue to wash your hands regularly
change and wash your face covering daily
if the material is washable, wash in line with manufacturer’s instructions. If it’s not washable, dispose of it carefully in your usual waste
practise social distancing wherever possible

You can make face-coverings at home. Find guidance on how to wear and make a
face-covering on GOV.UK.
*[PPE]: Personal protective equipment

Reviewer feedback on this answer:
Has specific information about when face masks should be worn. Fully addresses question.
The response answers the question clearly and also gives background information on why to wear a mask and who it actually may be helping. It also gives tips on how to properly use PPE.

Reviewer ratings:
Excellent
Excellent

Answer passage (source: UK):
page_title: Guidance Guidance for those who provide unpaid care to friends or family
section_headers: General advice
Facemasks
section_content: We do not recommend the use of facemasks as an effective means of preventing
the spread of infection, unless advised by a healthcare professional.
Facemasks play an important role in clinical settings, such as hospitals,
where staff are trained in the use of personal protective equipment (PPE) but
there is little evidence of benefit from their general use outside of these
settings.

Reviewer feedback on this answer:
Has outdated information about face masks that contradicts current WHO guidance.
While the response doesn't tell you when or where to use a facemask, it does let you know that there really isn't much of a point to it so there really isn't a "good" time.

Reviewer ratings:
Bad
Acceptable