• Dr. Scott Gottlieb told CNBC outdoor mask mandates are no longer necessary.
• "We have the opportunity to bring more activities outside. We know activities outside are lower risk than things done indoors," the former FDA chief said.
• "People could choose to wear a mask if they want to. I think there shouldn't be requirements" for masks outdoors, Gottlieb said.

Dr. Scott Gottlieb told CNBC on Monday outdoor mask mandates are no longer necessary at this stage in the coronavirus pandemic.

Public health officials should take a more relaxed stance on outdoor activities in general, said Gottlieb, who serves on the board of Covid vaccine maker Pfizer.

"People could choose to wear a mask if they want to. I think there shouldn't be requirements that they have to wear masks outdoors," the former Food and Drug Administration commissioner said on "Squawk Box."

Steps should be taken "to allow more gatherings outside, allow more large groups, allow sporting events, things of that nature," he added. "The weather is warming up. We have the opportunity to bring more activities outside. We know activities outside are lower risk than things done indoors."

White House chief medical advisor Dr. Anthony Fauci agrees about the risk of coronavirus transmission outdoors. In an interview Sunday, he suggested the Centers for Disease Control and Prevention could modify its stance on wearing masks outside.

"What I believe ... the country is going to be hearing soon is updated guidelines from the CDC," Fauci said on ABC's "This Week with George Stephanopoulos." "The CDC is a science-based organization. They don't want to make any guidelines unless they look at the data and the data backs it up. But when you look around at the common sense situation, obviously the risk is really very low, particularly if you're vaccinated."

President Joe Biden is expected to announce new CDC guidance on wearing masks outdoors as early as Tuesday, a source familiar with the discussions told NBC News. However, the source cautioned that the recommendations are still being finalized and they'll likely include guidance for fully vaccinated people versus those who are not.

The CDC's current guidance on face coverings includes the following: "Masks may not be necessary when you are outside by yourself away from others, or with people who live in your household. However, some areas may have mask mandates while out in public, so please check the rules in your local area (such as in your city, county, or state). Additionally, check whether any federal mask mandates apply to where you will be going."

In their own respective mask requirements, multiple states say people do not need to wear one when they are outside and maintaining at least 6 feet of physical distance from individuals who aren't in their household.

Gottlieb said he believes it's time to do away with outdoor mask requirements because vaccination levels in the U.S. are driving down new infections. More than 42% of the U.S. population has received at least one vaccine dose, including 28.5% who have been fully vaccinated, according to CDC data.

On Monday, the seven-day average of new daily coronavirus infections in the U.S. was about 58,160, according to a CNBC analysis of data compiled by Johns Hopkins University. That figure is down 14% from one week ago.

"The gains we're seeing right now against the virus are being solidified by vaccination and immunity in the population, whereas before the gains that we saw were the result of behavior, people being more prudent in what they were doing," said Gottlieb, who led the FDA during the Trump administration. "Now it's the result of immunity. We could be assured that these are going to be solidified."

Disclosure: Scott Gottlieb is a CNBC contributor and is a member of the boards of Pfizer, genetic testing start-up Tempus, health-care tech company Aetion Inc. and biotech company Illumina. He also serves as co-chair of Norwegian Cruise Line Holdings' and Royal Caribbean's "Healthy Sail Panel."