As the coronavirus started to spread, many medical experts, myself included, argued that wearing a mask offered at least some protection. But with medical and surgical masks in short supply, many people have turned to homemade masks.

Are these masks effective?

A recent study from Florida Atlantic University shows which ones might block the spread of respiratory droplets the best. The researchers used a generator to emit gas from a dummy’s mouth, to replicate a cough.

They found that the simplest masks — either a bandana or folded handkerchief — were basically ineffective. They each allowed droplets nearly 4 feet away from the face.

On the other hand, a fitted cotton mask only allowed droplets to travel a couple of inches. The researchers observed that the fit of the cotton mask was important, especially ones that provided a good seal along the edges and prevented leakage from the sides of the mask.

They also found that simple surgical masks worked well at preventing droplet transmission and may be a good option for people who can get them.

Still, no mask or face covering is 100 percent effective in blocking respiratory pathogens. It’s important to use masks in combination with social distancing, hand washing and other measures to prevent catching and spreading COVID-19.