Paris - So you have to wear a mask to help stop the spread of the new coronavirus? Wondering how to chose one? Or if it will slip off, or be suffocating?

While masks are everyday accessories in parts of Asia, for those not accustomed to wearing them the experience can be unnerving, even daunting.

Here are some tips for the uninitiated:

- Which mask? -

Unless you are a frontline health worker you do not need a high-spec respirator like the N95 or FFP2, experts say. Leave those for the professionals.

When it comes to other types of masks, the advice has shifted with the understanding of the epidemic.

Initially, health authorities and the World Health Organization said it was useless for the general population to wear masks in public.

What are the two main types of face masks?

Now it is increasingly recommended as part of the public health toolbox, along with frequent handwashing and physical distancing.

With medical personal protective equipment off the table, authorities have suggested people buy or make fabric face coverings.

The WHO has expressed doubts that these will offer full protection for the wearer, but notes that they could stop an unknowingly infected person from passing the virus on to others.

This matters because a significant minority of people with COVID-19 do not have any symptoms at all.

Surgical, N95 or similar?

Those wanting to make their own masks have no shortage of tutorials online to turn to for inspiration.

The website of the United States Centers for Disease Control (CDC) has instructions for how to make a no-sew mask by cutting up a T-Shirt.

Some countries have published manufacturing standards -- even for homemade masks.

In France, authorities recommend that they should be made from at least two layers of flexible and, importantly, breathable fabric.

How to make a homemade face covering?

There should not be vertical seams where it fits to the mouth, nose and chin to avoid leakage.

Masks produced for sale by textile manufacturers -- following either a "duckbill" or "pleated" pattern -- must filter between 70 percent and 90 percent of particles expelled by the wearer that are three microns in diameter. The average human hair is roughly 80 microns thick.

Very young infants should not wear masks because of the risk of suffocation. Regulations as to the exact age threshold depends on the country.

- How to fit it -

Once you have purchased or made your mask, there are some simple tips for wearing it comfortably and safely.

The main thing to remember is that a face covering does not replace other key virus avoidance measures: soap and social distance.

It may go without saying, but the mask should be worn on your face, not hung around the neck like a scarf, nor on the forehead like a bandana. This risks contamination.

As does sharing the mask with others.

To put one on, first wash your hands.

Then holding the mask by its strings, fit it snugly over your mouth, nose and chin and fasten it in place.

With surgical type masks, there is sometimes a rigid bar that goes over the bridge of the nose and can be pinched to fit the face.

It is important to ensure it fits comfortably.

A badly-fitted mask risks slippage and discomfort, tempting you to touch your face.

If you do need to adjust the mask while out, you will need to wash your hands first.

Single-use surgical masks can normally be worn for a maximum of a few hours before they should be replaced, depending on the type. It should be discarded earlier if it becomes wet or damaged.

Parisian commuters accept face coverings and social distancing rules

In France, the rules state even non-disposable masks should be worn only for around four hours, meaning you would need to pack several if planning to be using them all day.

When taking off the mask, first wash your hands.

Holding it by the fasteners, remove the mask without touching the potentially contaminated front section. Wash your hands.

- After use -

Single use surgical masks should be discarded after use, preferably in a closed bin.

For fabric models, washing instructions vary by country.

The US CDC says they should be washed regularly -- after each time they are worn -- using a mild detergent, then "dried completely in a hot dryer".

Countries where mask wearing is compulsory, recommended or optional (as of April 30)

In France, the advice is at least 30 minutes on a 60 degrees Celsius machine wash, then drying either in a machine or open air, then ironing.

Putting the mask in the freezer or microwave to try to kill the virus is not recommended.

Even fabric masks have a shelf life as the material degrades with washing.

At the slightest sign of wear, throw it away.