Elevators can make it easy for the coronavirus to spread. Here's how to lower your risk if you go back to the office.

• The coronavirus typically spreads via droplets when an infected person comes close to others.
• Viral particles can also live on surfaces like plastic and stainless steel for days.
• That could make elevators in offices risky as people return to work.
• But coronavirus risk can be managed when riding an elevator — here are tips from experts on how to do it.

Some New Yorkers began returning to their offices on Monday as the city entered its second phase of reopening.

The city's guidelines stipulate that offices can only open at 50% occupancy, but even that enforced distancing leaves one high-risk zone: elevators.

Research suggests the coronavirus spreads best in poorly ventilated indoor spaces in which people come within 6 feet for prolonged periods of time. Elevators check all those boxes.

Linsey Marr, an aerosol scientist at Virginia Tech, previously told Business Insider that may be especially true in high-rise office buildings, where elevators "are crowded and people ride in them for a long time, like a minute or more several times a day."

Here's how to lower coronavirus transmission risk when riding an elevator, according to experts.

Limit how much you talk

The coronavirus primarily spreads via droplets — particles larger than 5 micrometers — when an infected person coughs, speaks, sings, or sneezes. A study published last month found that talking loudly produces enough droplets to transmit the coronavirus to others, and that those droplets can linger in the air for at least eight minutes.

"There is a substantial probability that normal speaking causes airborne virus transmission in confined environments," the researchers wrote.

So limiting how much you talk when riding an elevator and encouraging others to do the same could help reduce risk.

Experts still aren't sure whether clouds of even tinier viral particles, known as aerosols, can linger in the air after an infected person has ridden an elevator. The World Health Organization has said that kind of transmission is not common with this coronavirus.

"If you're riding by yourself, the risk is extremely low," Marr said.

Still, a study published in April also found live virus in the air in and around two hospitals in Wuhan, China. The highest concentrations were observed in confined areas with little air flow.

"Many elevators do not seem to have mechanical ventilation, like a fan, beyond the natural ventilation that occurs when the doors open and close," Marr told NPR in April.

Wearing masks is crucial

Given the close confines and limited ventilation in some elevators, it's critical to wear a mask when riding, experts say.

New York City's reopening guidelines require employers to "advise workers and visitors to wear face coverings in common areas including elevators."

William Schaffner, a professor of preventive medicine at Vanderbilt University, put it more simply: "When in doubt wear a mask," he told Business Insider.

"Those masks make sure that if you happen to be unknowingly infected you won't give it to somebody else. And the reason other people wear it is so they don't unwittingly give it to you," Schaffner added.

Shortening your ride time, and consequently the duration of contact between you and other people, decreases transmission risk too, he said.

Social distance as much as possible

The number of people in a given space and how close they get to each other matter most when it comes to coronavirus risk, according to Schaffner. That's why the Centers for Disease Control and Prevention recommends that offices limit use and occupancy of elevators so that those inside can stay at least 6 feet apart.

While that may not be possible in smaller elevators, New York state has mandated that office elevators operate below half of their normal capacity.

If you come across a crowded elevator, don't get in. Wait for the next one.

Alternatively, "consider taking the stairs," the CDC suggests.

Don't use your fingers to press the buttons

Although it's not common, a person can get the coronavirus if they touch a surface or object that has viral particles on it and then touch their mouth, nose, or eyes.

Although the virus' lifespan on different surfaces depends on the surrounding temperature, humidity, type of surface, and other factors, two studies found that it lasts longest — up to seven days — on stainless steel and plastic.

So elevator buttons and doors could harbor viral particles for days. A May study even found the coronavirus' genetic material on elevator buttons in a hospital in Wuhan, China.

Both the CDC and New York state guidelines stipulate that commonly touched surfaces, including those in public elevators, should be frequently cleaned and disinfected.

Even so, Marr said it's important to "punch the buttons with something other than your fingers."

That could be a covered elbow, or your jacket or briefcase. If you have to touch the buttons directly, wash or sanitize your hands afterwards.