Ahem: so, that Duke gaiter study that's making the rounds:

If you run and ride and use a gaiter, please don't be too freaked out that it doesn't work.
To start, the study's *main purpose* is to validate a low-cost testing setup. It was NOT to test the masks themselves. 1/

I spoke with one of the authors, and he said they generally tested whatever they had on hand. It's also not systematic: most results were from ONE test subject. Notably, said subject's control (no-mask) droplet count varied by day, and was higher than others' results.

The test didn't differentiate between droplets that get thru the mask material versus around it. Another (non-Duke) researcher I spoke with said fit is a key factor. As @susanematthews writes in @Slate - it's possible that the gaiter just didn't fit well. https://slate.com/technology/2020/08/gaiter-study-flawed.html

How much does fit matter? In research at @UWMadison on how well masks blocked coughs, the *most-effective* mask was...a modified gaiter-style mask, with a nose piece and a drawcord. https://news.wisc.edu/coughing-visualization-illustrates-the-benefits-of-wearing-a-good-mask/

While the Duke test methodology is ingeniously cheap and easy to replicate (which was its point), at least one highly regarded aerosol scientist questions whether the laser is actually showing droplets/aerosols, or fiber-shedding: https://twitter.com/linseymarr/status/1293570019167739906?s=20

Finally, there are some questions about the error bands in the study. The candlesticks in this graph are meant to show median (the dot) and standard deviation. But as you can see, the deviation for some of the masks (including gaiter) is VERY wide.

What that means is that the gaiter may *not* actually be worse than no mask, which is the catchy headline that @washingtonpost @cnn and others have used, as @dylanhmorris notes: https://twitter.com/dylanhmorris/status/1292568439975022593?s=20

Finally-finally: it's worth noting that most of the emissions in the gaiter result are smaller, airborne droplets. That is absolutely notable: increasing evidence shows that airborne/aerosol transmission may be a (or the) primary route of disease spread for SARS-CoV-2.

But: we're talking about people wearing masks outside, for exercise. A gaiter isn't the best choice for a trip to the grocery store or other indoor errands. But outside, with fresh air dispersal, UV light, and limited contact time with others that may be only a few seconds?

The gaiter is probably fine, and it does appear to limit larger droplets. You can also double the thickness, or use one made of a different material.
Still concerned? I'm testing masks right now for @outsidemagazine and hope to have a story up soon with some results/recs.