RALEIGH, N.C. (WTVD) -- As COVID-19 continues to affect the world, researchers wanted to know what activities are safe and just how safe are they.
A new study published earlier this month in the scientific journal, Environmental Science and Technology, answered some of those questions.
Researchers across multiple universities studied how different factors influence transmissibility and a person's ability to get sick.
Unsurprisingly, the highest risk was in settings where people were heavily exercising without masks on in crowded and poorly ventilated spaces. Researchers estimate in those conditions individuals have more than a 99% chance of catching the virus.
"I think that confirms what everyone understands qualitatively that if people aren't wearing masks, there's more risk. And if there's lower ventilation rate, there's more risk," said one of the researchers Dr. William P. Bahnfleth, an architectural engineering professor at Pennsylvania State University.
Researchers said the easiest way to catch COVID-19 is to do a combination of activities they labeled as the riskiest. These include gathering indoors in a place with poor ventilation like a gym, nightclub, or school classroom. Leaving off masks, staying at a place for a long time, and exercising or singing and shouting are other top ways researchers found people could easily catch COVID-19.
Even in well-ventilated spaces, people face a 54% chance of transmission if they are shouting and singing at a concert or nightclub and an 84% chance if they are heavily exercising at a gym.
"We don't know as much as we should about, say the effective ventilation rates and reducing risk. But this model gives us a way of analyzing events they've already happened to see where the risk really increases," Bahnfleth explained.
Researchers also predicted there is only around a 2.6% chance of catching the virus if people are sitting silently indoors, like at a movie theater, even if they don't wear masks among many people.
Meanwhile, the lowest risk was when people were wearing masks and were silent with a few people outdoors. All scenarios where individuals were outside carried less than a 3% chance of infection regardless of the number of people, activity, or masking.
The study does reveal how big of an effect factors such as a mask, ventilation, and occupancy can have. The risk for catching COVID-19 at a gym increases by five-fold between wearing a mask around a few people in a well-ventilated gym vs. not wearing a mask around many people in a poorly ventilated space.
Similarly, the risk more than doubles if people are singing at a nightclub unmasked just based on low vs. high occupancy.
Bahnfleth said it can be difficult to determine how well ventilated certain buildings are. He would like to see buildings receive certification in the future that is based on their air quality.
"Buildings that are only designed to the minimum code level of ventilation and filtration would probably expose someone to quite a bit of risk in a high-density situation like a crowded restaurant," he said. "So, if you don't take additional measures to reduce risk in most public settings, then there's a significant risk when there's a high incidence of a disease in the population."
The overall risk factor depends on the size of the crowd and the type of enclosed space. The transmissibility of COVID-19 also depends on the variant and how many people are currently infected in the area.
Bahnfleth said he envisions this data being useful for the next pandemic to offer authorities better guidance on how to most effectively shut an outbreak down.
"I think if we use the science and engineering has been developing over the last couple of years to develop better buildings and to develop better plans for reacting when there's an epidemic then this will be useful," he explained.
To avoid spread, researchers recommend meeting outdoors, keeping groups small, minimizing time together, wearing masks indoors, and don't sing, shouting, or doing heavy exercise.
"Even if we don't have precise answers today, we know the things that you can do to make yourself safer there's no such thing as safe, but safer. And please do them," Bahnfleth said.