RELATED: The CDC Says Don’t Go to These 2 Popular U.S. Destinations Right Now.ae0fcc31ae342fd3a1346ebb1f342fcb During a Sept. 7 appearance on CNN’s New Day, Fauci was asked by host Jim Sciutto about whether or not the return of full crowds to college football games could create the potential for further spread of the virus. The top health official quickly condemned footage of the gatherings of unmasked spectators, saying: “I don’t think it’s smart.” “Outdoors is always better than indoors, but even when you have such a congregate setting of people close together, you should be vaccinated,” Fauci then said. “And when you do have congregate settings, particularly indoors, you should be wearing a mask.” A mounting body of evidence that the Delta variant can spread outside has led some health officials to enact outdoor mask mandates. In August, the Centers for Disease Control and Prevention (CDC) also updated their guidance to suggest that while moving activities outside remains a much safer choice, it’s still advisable to maintain six feet of distance between people and wear a mask whenever social distancing isn’t possible. Some sports organizations have instituted health policies ranging from mask mandates to vaccine requirements in recent months in response to the rising COVID numbers brought on by the Delta variant. But since such measures are far from universally adopted yet, Fauci pointed out that there will likely soon be more activities that will become harder for people to take part in if they haven’t received their shots. “We could be stuck in outbreak mode, and that’s why I think what you’re going to be seeing is…a lot more local mandates,” he said. “There are gonna be organizations, there are gonna be universities, there are gonna be colleges, there are gonna be sports events, travel events, where the rule is going to be if you wanna participate, you get vaccinated. If not, sorry, you’re not going to be able to do it.” RELATED: You’re Banned From Traveling Here Now, Even If You’re Vaccinated. Some experts warn that a combination of factors could create conditions that can spread the variant, even at outdoor venues such as stadiums and arenas. “There’s a limit to how much the air currents can dilute and disperse virus, and so if you have a crowded outdoor environment, you may circumvent that beneficial dilution effect,” Charles Haas, PhD, a professor of environmental engineering at Drexel University, told The Philadelphia Inquirer. According to Erin Bromage, PhD, a biology professor at the University of Massachusetts, Dartmouth, even venues with outdoor seating can still have plenty of high-risk spaces, especially crowded or indoor areas such as lines for restrooms or concessions. “I would mask up going into those spaces,” he told Boston CBS affiliate WBZ-TV. RELATED: For more up-to-date information, sign up for our daily newsletter. But while masks may go a long way in keeping yourself and others safe, Lisa M. Lee, PhD, associate vice president for research and innovation and a research professor of population health sciences at Virginia Polytechnic Institute and State University, says that a combined approach is the best plan of action for outdoor gatherings and crowds—beginning with getting vaccinated. “This is the most important precaution you can take to protect yourself and those around you, as vaccinated people are about 25 times less likely to get sick if they get the Delta variant, in addition to being less likely to get infected at all,” she told Men’s Health. “If you live in an area with high rates of COVID-19 cases, layer your protection—start with a vaccine and add a mask and physical distance as you interact with others whose vaccination status is unknown and as the size of [any] crowd increases.” RELATED: Dr. Fauci Warns You Not to Do This If You Got Moderna.