UPDATE: Aug. 19, 2020: A study that found that neck gaiters and bandanas do nothing to help block respiratory droplets that can spread COVID-19 has been called into question.
A Duke University research team's conclusion that a fabric gaiter will create more spread by splicing big droplets into smaller droplets is unlikely, a leading expert on aerosols told the New York Times.
According to lab tests led by Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, neck gaiters provide some degree of protection, with some homemade masks performing better than the gaiters and some performing worse.
For contractors who ditched their gaiters because of the original study and are now wondering what to wear on the jobsite, the bottom line for fabric masks is that two layers are better than one, and that a snug fit with no gaps is best, according to the Times article.
“There’s nothing inherent about a neck gaiter that should make it any worse than a cloth mask," Marr told the Times. "It comes down to the fabric and how well it fits.”
Dive Brief:
- A new study looking at the effectiveness of face coverings using optical imaging technology has ramifications for the ways that construction workers protect themselves on jobsites. The study found wide discrepancies in the effectiveness of different types of masks to restrict the spread of COVID-19.
- Researchers from Duke University looked at how different choices mitigated the spread of respiratory droplets during regular speech and found large differences in the way various masks performed.
- The study, published by the American Association for the Advancement of Science, looked at a wide range of masks and mask materials, from surgical and N95 masks to those made of cotton, fleece and bandanas. It found that some face coverings — spandex neck gaiters and cotton bandanas — are actually no better than wearing no mask.
Dive Insight:
The research team looked at 14 commonly available masks or masks alternatives, one patch of mask material, and a professionally fit-tested N95 mask. It found that the top five types for keeping droplet spray to a minimum (under 0.2 relative droplet count) are:
- Fitted N95 mask
- Surgical mask
- Poly/cotton mask
- Polypropylene mask
- A swath of polypropylene material
Four two-layer cotton pleated masks, a one one-layer cotton pleated mask and a knitted mask were found to be relatively helpful at minimizing spray, coming in at less than 0.4 relative droplet count.
The study also highlighted the types of face coverings that are not helpful in mitigating droplet spread and brought up many considerations for workers on construction jobsites, especially those who prefer to wear lightweight masks such as neck gaiters. These were found to disperse the largest droplets into a multitude of smaller droplets.
“Considering that smaller particles are airborne longer than large droplets (larger droplets sink faster), the use of such a mask might be counterproductive,” the researchers wrote.
Furthermore, the study found that valved N95 masks, which are commonly used in construction, can decrease the protection of those surrounding the wearer.
“Such a valve allows air to move from the wearer’s mouth and nose through the mask without going through the main filter,” the study said. “While this may make exhaling easier, at the same time, it may permit viruses to get on through to the other side.”
In the construction industry, face coverings to prevent the spread of COVID-19 are recommended and even required on most jobsites and 67% of respondents to a recent Construction Dive survey said that they are an important means of protection.
While construction pros said they see the need for face coverings on jobsites, they don’t always like having to wear one. Drawbacks include that they can make the wearer feel hot and tend to fog eyeglasses and safety goggles. Other reasons mentioned were that they make it hard to breathe during strenuous activities, they can fall apart, and they irritate the skin behind the ears.
Despite the new findings from the droplet study, the researchers said that because COVID-19 is such a new disease there is still much to be learned about how it is transmitted.
“Determining mask efficacy is a complex topic that is still an active field of research, made even more complicated because the infection pathways for COVID-19 are not yet fully understood and are complicated by many factors such as the route of transmission, correct fit and usage of masks, and environmental variables,” they said.
