Kalina Mladenova, Contributing Illustrator

The implementation of mask mandates around the country was correlated with people spending less time at home, a new study by a Yale School of the Environment team concluded.

Sparked by curiosity about the behavioral effects of various COVID-19 interventions, four researchers, including professor of natural resource economics Eli Fenichel and School of the Environment postdoctoral associate Youpei Yan, set out to understand the effect mask mandates had on how much time people spent at home. Using smartphone location data and careful analysis, they concluded that people leave their houses more when mask mandates are in place. This finding aligns with previous public health research into how people make trade-offs when it comes to their personal risk of infection.

“When you throw out a whole bunch of behavioral policies, they are not going to be additive,” Fenichel, the senior author of the study, said. “People will make trade-offs. And I think people need to be mindful about the trade-offs that they’re making.”

Back in April, Fenichel said, as COVID-19 cases and mask mandates were both on the rise, he noticed how many people were leaving their houses for non-essential trips with the mindset that wearing a mask would render their trip completely safe. At that time, and to this day, research has not shown that the cloth masks worn by average Americans completely eliminate the risk of getting COVID-19.

This led him to wonder whether there was any correlation between the implementation of mask mandates and how much time people spent away from their houses in the midst of the pandemic. Previous studies on similar phenomena — known as “risk compensation” — can be found in scientific literature, according to Fenichel.

“Probably one of the best examples is risk behaviors with HIV,” Albert Ko, chair of the Yale School of Public Health Epidemiology Department, said. “You have people who, you know, they’re on pre-exposure prophylaxis and they may not use condoms. There are people … entering on dangerous, potentially harmful risk behaviors.”

The central idea is that when certain preventative measures are implemented, some people may engage more often in risky behaviors. Understanding how these dynamics work in the context of COVID-19 is a new, yet vitally important, field of study, according to the researchers.

As the article explains, the researchers used SafeGraph, a company which anonymizes and collects data on people’s whereabouts, and found that mask mandates are indeed correlated with Americans spending less time at home.

“This finding is not surprising and seems reasonable,” Paul Cleary, Anna M.R. Lauder professor of public health in the Department of Health Policy and Management, wrote in an email to the News. “This is why so many commentators … emphasize that masking does not substitute for social distancing or … other preventive behaviors.”

The University’s own guidance, as laid out in the community compact, stipulates that all adherents must “wear face coverings in shared or public spaces,” but also compels all students, faculty and staff to practice social distancing and take other preventative measures to limit the spread of COVID-19.

According to Fenichel, public health guidance on masks has evolved since the study was in its early stages. Initially, he noted, there was not good communication on the effectiveness of masks. Ko also highlighted the ongoing discussion on the effectiveness of various types of masks. Fenichel pointed out that this is worrying, as people make trade-offs between the wide variety of policies being presented at the same time.

“The key message here is to be a little bit more mindful about the decisions you’re making to protect yourself during the pandemic,” Fenichel said. “I am not saying that masks are bad. What I’m saying is that I think what we did is we threw the kitchen sink from a policy perspective, at this, without being thoughtful about perhaps some of the interactions among those policies. And I think that was confusing for people.”

The new question is whether another COVID-19 management strategy, vaccination, will cause a similar increase in risk compensation and, if so, what the resulting effects will be. Fenichel predicts that it will cause this type of behavior, citing comparable research conducted on vaccines for other pathogens.

Yet Fenichel is slightly less worried about vaccines causing people to leave the house more, given how much protection vaccines provide against the virus as compared to wearing a mask. He points out that even in a setting where not the entire population is vaccinated, people will still be more protected in public than they might otherwise. Ko noted that the specific type of vaccine is also important when considering its effectiveness, given that not all are equally protective.

“It depends on the vaccine,” Ko said. “Not all of the vaccines … may be … entirely transmission blocking, but they may reduce the risk of transmission. So, if people who are unvaccinated go out and aren’t using face masks and so forth, and, you know, but they could be infected and they can transmit [the virus].”

Nevertheless, as was reiterated by the University’s COVID-19 coordinator, Stephanie Spangler, in her most recent weekly update, wearing face coverings is a vital step in protecting the community. Fenichel highlighted that while it might be more complex on the policy level, wearing a mask is and should be an easy decision that all individuals make.

According to PR Newswire, the value of the worldwide reusable mask industry is expected to exceed $7 billion dollars by 2027.

Amre Proman | amre.proman@yale.edu