(CNN) — Four types of non-medical face masks were tested by Florida Atlantic University researchers to determine which was most effective at stopping droplets, such as those that spread coronavirus.

The study was published Tuesday in the journal Physics of Fluids.

In the experiment, a mannequin’s head was outfitted to deliver a simulated sneeze or cough using a manual pump and a smoke generator. A laser was used to map the paths of droplets.

The tests were repeated with the mannequin’s nose and mouth covered by certain masks readily available to the general public.

The results:

Uncovered: Droplets traveled more than 8 feet. By 12 feet, most droplets had fallen to the ground.

Bandana covering the nose and mouth but loose at the bottom: 3 feet.

Handkerchief or T-shirt, loosely folded and secured over the ears with rubber bands: 15 inches.

Cone-style non-sterile commercial mask: 8 inches.

Stitched mask, closely fitted, with two layers of quilting fabric and elastic loops or cloth ties: 2½ inches.

The World Health Organization says governments should encourage people to wear non-medical, fabric masks, especially in settings where physical distancing of at least 3 feet is not possible — such as on public transport, in shops or in other confined or crowded environments.

In the US, the Centers for Disease Control and Prevention recommends cloth face coverings to protect others in places where social distancing can’t be maintained.

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