Gov. Charlie Baker and the Massachusetts Department of Public Health’s stay-at-home advisory, issued earlier this week, recommends that residents stay inside, except to address “essential needs” and to “get some fresh air and exercise.”

But when you’re outside, what sort of precautions should one specifically take to avoid contracting the coronavirus? One expert said that residents seeking fresh air or exercise should take considerably steeper precautions on top of those currently recommended by most states and the federal government.

When outside, most governments, including Massachusetts, have generally recommended a 6-foot rule between yourself and others. The DPH advisory doesn’t specifically mention distances, though it does recommend that employees and customers at businesses of “essential service” keep at least 6 feet away from each other.

But Jose Jimenez, a professor of chemistry at the University of Colorado specializing in aerosol science, suggests that people keep more — significantly more — than 6 feet of distance between themselves and others when spending any time indoors or outdoors.

“The best analogy is when someone is smoking tobacco or marijuana,” Jimenez said. “Think about how many times you have walked by people and smelled tobacco or pot smoke that someone else had exhaled. Often, those people were farther (away) than (6 feet).”

“If that happens, we are inhaling the contents of someone’s lungs with limited dilution. Then we could inhale enough viruses to get sick, if the person exhaling the air was sick. Therefore, the (6-foot) rule, while useful, is not enough. We have to imagine that everyone we cross paths with is smoking, and we want to make sure that we never smell their smoke. So we want to keep larger distances, especially indoors or with light winds, or if they are upwind of us.”

“Personally, I’ve been trying to keep at least 25 feet from anyone outdoors.”

The difference between most recommendations and his own feelings, Jimenez explained, is due to what he sees as a partial misconception in the scientific community and in the public. Jimenez said that’s because of the general perception that the virus exclusively spreads through coughing and sneezing. But, Jimenez said that’s not entirely the case.

“We know that viruses similar to the current one are present in particles in exhaled breath. This does not require coughing or sneezing,” Jimenez said. “Many of the viruses are present on fine particles, which stay in the air for hours, without settling on the ground. Many in the medical community think that the virus is only present on large droplets that settle very close to the person breathing. This is wrong, and there is a lot of evidence against it in the scientific literature.”

Joggers, in particular, should keep 25 feet or more of distance between themselves and others, Jimenez says.

“Imagine that they are smoking four cigarettes, and doing so really quickly. So I would keep even larger distances,” Jimenez said. “Joggers should be proactive and keep really large distances — 25 feet or more — from anyone they cross paths with.”