Alta mayor calls for quiet after study at resort shows how loud talking can spread coronavirus droplets around

A team of MIT students analyzed lodges, lifts and locker rooms at the ski area to determine where guests are most at risk

(Francisco Kjolseth | The Salt Lake Tribune) A sign at Alta Ski Resort encourages people to social distance in the wake of the coronavirus pandemic on Wednesday, March 25, 2020. A group of MIT students analyzed several lodges in town and parts of the ski area to determine where guests are most at risk for catching the virus and how decrease their odds.

With snow absorbing the ambient chatter, the quiet at the top of an empty ski run can have a Zen effect.

Likewise, one elected official is suggesting a similar hush in locker rooms, bathrooms, lift lines and restaurants in and around Utah’s ski resorts could calm the spread of COVID-19.

“What I’m fantasizing about,” said Town of Alta Mayor Harris Sondak, “is our [variable messaging signs] saying: ‘Be boisterous and kill your bro.’”

Sondak isn’t lobbying for a more library-like atmosphere based on a hunch or even the latest Centers for Disease Control and Prevention guidelines, though. No, as seems appropriate for an elected official who also happens to be the chair of the department of management and ethics at the University of Utah’s school of business, he has commissioned a study. Since August, a team of MIT students have scientifically analyzed how and where residents and guests of Alta and its surrounding ski areas have the greatest probability of catching the deadly virus this ski season.

The results may leave skiers speechless.

But first, a little background.

Pain points

Sondak had plenty of reasons for concern when ski resorts, including Alta Ski Area, started announcing their plans to open for the 2020-21 season.

On the one hand, ski resorts have time and again been the sites of mass spread. Last spring, outbreaks in tiny ski towns across the United States rivaled those of major metropolitan areas in terms of percentage of the population infected. A bartender in Ischgl, a ski town in Austria, is believed to be the source of coronavirus cases in at least 40 countries on five continents.

On the other hand, skiing is the Town of Alta’s lifeblood. If the ski areas and lodges close down, the hamlet of 384 people couldn’t generate enough property and sales taxes to pay for the services used by the throngs of backcountry skiers, snowshoers and summer sightseers who access a vast network of trails from there.

In other words, keeping Alta and the nearby Snowbird ski area open and safe was essential. Only, Sondak wasn’t so sure the measures the resorts were enacting, which mostly were riffs on recommendations from the National Ski Areas Association, which in turn were based on general CDC and World Health Organization guidelines, would be enough.

“I’m not confident that this is going to go well,” he said in October, “and I really wish I was.”

Then a colleague who is a professor at MIT reached out. He offered to have a group of students study Little Cottonwood Canyon’s coronavirus “pain points” and make recommendations, for free. They would look not at generalities, but at exact specifications — from a building’s square footage to its ceiling height, from the speed of a chairlift to the air flow around it.

The information gleaned from the analysis could then be used to advise other businesses — such as childcare facilities or even sports stadiums — on best practices. Alta was the only ski town included in the study.

“What we’ve learned is that there’s no ‘one size fits all,’” said Anette “Peko” Hosoi, an associate dean of engineering at MIT who helped create the class. “You really have to work with the communities and talk to the community to understand what are the things you’re trying to achieve.”

Soon, several lodges in Alta, the Utah Transit Authority and, to a point, the Alta ski area had made their information available. Snowbird, located just down the canyon, used an independent consultation group to help it determine its COVID-19 protocols and declined to participate.

Silence is golden

By November, the students — Amar Dhesi, Emma Rosz Kelley, Sarah Timmons and Guang Cui — knew the exact specifications of a typical UTA bus. They knew how fast it travels, what the speed of the wind coming through the windows would be at that speed and how many particles the air circulation system can filter out.

They entered that information in a modeling system created by Hosoi and Paul Tessier with the backing of the National Institute of Health. The model also took into consideration factors like the amount of outbreak in the area (1.2% in Salt Lake City) and the efficacy of the masks passengers were wearing. Then, like magic, or really more like advanced math, they’d discover the probability of a Ski Bus rider catching COVID.

Turns out, it’s pretty low.

UTA plans to run the bus with no more than 20 people at a time, all of them masked, socially distanced and speaking at a conversational level. With those measures in place for an hour-long trip, fewer than five out of every 1,000 riders (.5%) would get sick, which is what the team set as its barometer for determining if an activity was risky.

The real revelation though? If passengers don’t speak at all, the bus could accommodate up to 60 riders.

“So in an emergency evacuation context,” Sondak said, “we can get people out at three times the rate that they came in. But they’re going to have to not talk.”

Lifts proved to be no issue at all. Even if a full chair is stalled for a few minutes, the outside airflow is enough to dissipate infected air particles. The lift line, too, posed little problem as long as people in them were masked and weren’t shouting or singing.

With the good news, though, comes the bad.

The CDC has found that the airborne droplets carrying COVID-19 increase tenfold as a person’s volume increases. So if a quiet infected person emits 20 particles per second, a quietly talking person emits 200 and a loudly talking person emits 2,000. (Someone who is coughing or sneezing emits 200,000, and makes all scenarios unsafe, according to the model. So for the purpose of the study, the group assumed everyone to be asymptomatic). A mask can also block some particles.

But take away the mask and raise the volume, and … well, that’s indoor dining.

“It’s certainly the most concerning result,” Sondak said. “And it’s got implications.”

The students took the exact specifications of a couple dining areas at lodges in the town of Alta and at the Watson Cafe at the ski resort. They entered the stats from each lodge into the model with a two-hour dining time (Watson’s was modeled with a half-hour dining time). The result was stomach churning. Even with tables set six feet apart, diners in a loud restaurant had a 60% chance of catching the virus.

They tweaked the dining time, virtually added more HEPA air filters, reduced seating.

“We could not find a reasonable set of protocol that reduced infection below this half-percent level,” undergraduate student Rosz Kelley said in an informal presentation to the Alta city council in November.

Risk vs. reward

Mike Maughn, president and general manager of Alta Ski Area, said he already expected indoor gathering places would be the riskiest on the mountain. That’s why Alta and every other Utah ski resort spent the summer installing more outdoor dining tables, walk-up order windows, propane heaters and food trucks.

He said there will always be a risk, but he thinks he can get it down to a 5% chance of contagion within the resort’s three dining areas.

“I’m comfortable offering that with that type of a situation,” he said. “But what I want skiers to know — it’s one of my things up front — is we’re trying to provide outdoor recreational opportunities. The risk is fairly low compared to others, but there is still a risk. I think everyone has to realize that, you know, we cannot totally eliminate the risk.”

Sondak agreed. The only way to have zero risk is to shut down, and he said that’s not what he’s advocating.

He is, however, encouraging businesses to look at the scenarios generated through the modeling system and find ways to improve guests’ odds of staying healthy. Because if guests stay healthy, they’ll keep coming and a full ski season just might be a possibility.

That would be something worth shouting about. But odds are Alta’s mayor will opt for a quieter celebration.