Coronavirus particles have been found in spit, mucus, poop, semen, floating through the air, and on various surfaces, like doorknobs and packages.

But your chances of getting sick after coming into contact with the virus in these different situations vary. Here are the five ways we know the coronavirus can spread, and how risky each one is for you.

1. You're most likely to catch the coronavirus after other infected people cough, sneeze, or talk near you

The coronavirus' main mode of transmission is via respiratory droplets: The particles travel best between people in little drops of liquid — saliva and mucus, usually. These typically travel 3 to 5 feet.

If an infected person coughs, sneezes, sings, talks loudly, or eats within that distance of someone healthy, droplets could land on them. Then if the particles enter a person's eyes, nose, or mouth, they can become infected.

An infected person can transmit the virus without ever knowing they had it — about 35% never show symptoms, according to the CDC. 

Respiratory droplets are usually more than 5 micrometers in diameter. That's relatively heavy, so they generally stay in the air for less than a minute until gravity pulls them down.

Maintaining a distance of 6 feet from others, avoiding touching your face, washing hands thoroughly and frequently, and wearing gloves can help prevent this form of transmission.

2. The coronavirus can live in poop, so exposure to raw sewage could be risky

Research suggests the virus could also spread via fecal matter: Multiple studies have found traces of it in infected patients' poop.

This is a health risk in places where waste-management systems can't adequately treat raw sewage. If contaminated water reenters the water system and then gets used for cooking, farming, or hygiene practices, there's a rsk of infection.

In some cases, exposure to contaminated feces can also be a problem if people use the bathroom then don't wash their hands before touching others or handling food. (In medicine, this is known as fecal-oral transmission.)

Accordingly, careful food-handling and washing is also important. Both the US and Chinese Centers for Disease Control and Prevention recommend boiling drinking water if there's a possibility it could be contaminated with sewage, and avoiding raw food like shellfish or produce that may have been harvested or washed in contaminated water.

3. The virus can linger in the air in the form of particles known as aerosols

Scientists know that viral particles can linger in the air in the form of aerosols (which are smaller than droplets), but they still aren't sure of the concentration required to infect a person who walks through that space later on.

This is known as airborne transmission; the measles virus can spread that way, living for up to two hours in an airspace where an infected person coughed or sneezed.

Coronavirus aerosols pose the biggest threat in healthcare settings. Research published last month in the journal Nature found that there were high concentrations of live virus in the air in and around certain areas of two hospitals in Wuhan, China. The study showed that viral particles were present in air samples from crowded places, poorly ventilated bathrooms, and rooms in which healthcare workers removed their protective equipment.

The Centers for Disease Control and Prevention also says that certain hospital procedures, like intubating a patient, "could generate infectious aerosols." A recent CDC study found that the coronavirus could travel up to 13 feet (4 meters) as an aerosol in hospital settings.

However, when aerosolized virus particles are dispersed in a well ventilated room, only small amounts linger. It's unclear if that'd be enough to infect someone.

4. Virus particles do not spread easily on surfaces, according to the CDC

The CDC updated its guidance last week to clarify that the coronavirus does not easily transmit via contaminated surfaces. (That wasn't completely new information — the CDC has said for months that the main way that the virus spreads is via droplets.)

The risk with surfaces is that droplets could land on them after a sick person talks, coughs, or sneezes nearby. Another person could then touch these surfaces and subsequently touch their face, thereby getting infected. But the risk of that is low.

Research has shown that live coronavirus particles can survive for anywhere from three hours to seven days on surfaces, depending on the material. But — as with aerosols — the existence of live virus particles in any concentration doesn't necessarily translate into a new infection.

5. The coronavirus has been found in semen, but it's not clear yet whether it can be sexually transmitted

A study from Chinese scientists published in the Journal of the American Medical Association found coronavirus particles in the semen of 16% of male patients studied — both from patients who had active infections and those who had recovered.

However, the researchers aren't sure whether the virus spreads through sexual contact. Many types of viruses that aren't sexually transmitted have been found in semen in the past.

"The presence of viruses in semen may be more common than currently understood, and traditional non-sexually transmitted viruses should not be assumed to be totally absent in genital secretions," the researchers wrote.