What are the rules and guidance for face masks and coverings?

MPs have been told they should wear face coverings in Parliament, following Covid outbreaks at Westminster.

Masks are not a legal requirement in most situations in England, but the health secretary has said this could change if the NHS comes under "unsustainable pressure" this winter.

In Scotland, Wales and Northern Ireland they are still mandatory on public transport and many indoor areas.

Under the government's Covid "Autumn and Winter Plan", Sajid Javid said face coverings would continue to be recommended in crowded and enclosed spaces.

But he warned they could be legally required again under "Plan B" contingency measures.

Meanwhile the UK Health Security Agency has asked MPs and peers to wear masks and cancel some activities in Parliament buildings, for the next two weeks.

Face coverings have already been made mandatory for everyone else working in or visiting the House of Commons.

Although face coverings are no longer compulsory in schools in England, head teachers and health officials can ask staff and pupils to wear them in response to local circumstances.

Schools in Bedfordshire, Trafford, Cambridgeshire and West Yorkshire have already reintroduced face coverings.

Businesses and travel operators can set their own rules for customers and passengers.

For example, Transport for London requires face covering for travel on the Underground and on buses.

However, it's not a legal requirement - staff can't issue any fines, although they can stop you from boarding a service or ask you to leave.

In other areas rules differ depending on which transport you are using.

In Greater Manchester, Mayor Andy Burnham requires face coverings on trams. He also wants them to be worn on other public transport such as buses, but these are privately run.

In addition:

Many retailers have announced they still want shoppers to wear face coverings, including Sainsbury's, Tesco and Waterstones.

Most people could be refused service, entry or the right to travel if a firm enforces a requirement to wear a face covering even if it's not legally required.

Companies decide their own health and safety measures, and insisting on masks could be a reasonable rule, says Adam Wagner, a barrister at Doughty Street Chambers.

However, they would not be able to discriminate. So, if you are currently exempt from wearing a mask - for example if you have breathing difficulties - companies would probably have to continue to honour that exemption, says Mr Wagner.

The British Medical Association, which represents doctors called for the continued use of masks.

England's chief medical officer Chris Whitty and chief scientific adviser Sir Patrick Vallance said they will continue to wear them.

Evidence suggests transmission mainly happens indoors where people are close together.

Face coverings worn over the nose and mouth reduce the spread of coronavirus droplets from coughs, sneezes and while speaking.

The main purpose is to protect others although there is some evidence they offer protection to wearers,.

Masks can also help reduce virus spread from contagious people with no symptoms.

It should:

The highest level of protection is provided by FFP3 (or similar) masks worn by healthcare workers in high risk settings. A recent study found FFP3 masks could provid up to 100% protection against Covid.

Hospital staff wearing standard surgical masks were much more likely to catch the virus.

Members of the public can buy FFP3 masks, but they won't provide the highest protection unless fitted correctly.