-In recent weeks, the United States has seen
the largest surge in the number of novel coronavirus infections
since the start of the pandemic.
Health officials have warned that the virus
can spread through close contact with an infected individual.
In October, the Centers for Disease Control revised
and expanded its guidelines,
and acknowledged that the virus can spread
through small airborne droplets that we exhale,
and can sometimes travel distances greater
than six feet and remain in the air for hours.
The agency said the risk of transmission
increases in enclosed spaces and those with poor ventilation.
In order to visually illustrate those risks,
The Washington Post used a high-tech infrared camera
capable of detecting exhalation.
The camera's advanced technology is more typically used
in military and industrial settings,
such as detecting methane-gas leaks in pipelines.
In 2013, it was deployed by law enforcement
during the 20-hour manhunt for the Boston Marathon bombers.
The highly sensitive camera detects variations
in infrared radiation
that are not visible to the naked eye.
The camera was fitted with a filter
that specifically targets the infrared signature
of carbon dioxide, the gas we exhale.
The carbon dioxide is then used to map the partial path
of these nearly invisible airborne particles,
including droplets that travel
within our exhaled breath in real time.
A highly sensitive digital filter is applied here
to emphasize airflows.
A virus, when airborne, will move with the airflow
shown by the infrared camera.
Here, we see a person exhaling particles.
And if present, an airborne virus,
like the novel coronavirus,
will move with the heated carbon dioxide airflow,
captured by the infrared camera, before dissipating from view.
-You are not directly seeing, maybe, the droplets.
What you're seeing is the overall effect
of this breath plume that's coming out.
-The Post used the camera system to illustrate how airflows,
capable of transporting airborne viral particles
transmitted in our breath,
could travel under various circumstances
and spread COVID-19.
According to experts who spoke with The Post,
the footage underrepresents the potential risk of exposure
from these airborne particles,
capable of potentially transmitting the virus.
Those particles spread farther or linger longer
than the visible exhalation plume,
which dissipates quickly to a level of concentration
that is no longer detectable by the camera.
-Environmental factors, such as airflow in a space,
wind, and sunlight can dampen the transmission of the virus,
even when in proximity of a person infected.
As temperatures drop and people move indoors,
family gatherings can become superspreader events.
-Winter basically brings more people indoors,
where there's more crowding
and there's less room for social distancing.
-Because the coronavirus is a virus
that can spread distances farther than six feet,
precautions such as social distancing
are not silver bullets when it comes to gathering indoors.
-If you have a number of people in the indoor environment,
the virus kind of continues to be built up.
And that, I think, is one of the biggest factors to watch out
for as we get into the winter season.
-In this video, filmed indoors,
two people are talking one foot apart.
The people who were filmed standing together without a mask
were in the same household.
The camera operator wore a mask and stood six feet away.
-Because they are close enough, you can see clearly
how the exhaled air
from one person reaches the other.
-According to Jimenez,
the exhaled breath from each person
reaches the other with little interference.
The risk of transmission is increased by prolonged
duration of exposure,
and concentration of viral particles
in a confined space, like a room.
-So, if you were within one meter of me,
and you weren't wearing a mask,
and we were talking for like 10 to 15 minutes,
clinically in infectious diseases and infection control,
that is sufficient exposure to infect you
from an aerosolized source of virus.
-Here is a person indoors, laughing without a mask,
and another talking on the phone
while wearing an unfitted surgical mask.
These conditions simulate everyday situations
where a virus could potentially spread.
As seen in these examples,
the breath plume changes directions when wearing a mask.
When not wearing a mask, the droplets capable
of transporting a virus project forward.
If the mask is properly fitted, it can filter the droplets
and redirect the exhalation.
When this happens, there may be less of the virus in the air
by the time it reaches the other person,
reducing the chance of infection.
-So, let's say you have a hundred droplets
coming out from the mouth.
By the time they get past the mask,
maybe there's only 80, maybe there's only 50,
depending on what quality of a face mask you're wearing.
But either way, it's going to reduce, to some degree,
the number of droplet coming out.
-In this video, filmed indoors,
two people are talking and wearing masks.
-So much is contained by the mask.
I don't see any air crossing that zone at all.
-Masks can limit the transmission of the virus,
but the risk of transmission to others increases
if the mask is not properly fitted.
-If there is a person that's wearing a mask,
and it's not well adjusted,
what you see in the videos is that it goes backwards,
because the curvature of the mask sends the air behind you.
So the last place where you want to be is behind a person
whose mask is not fitting well, because if there are viruses,
that's where the viruses are going to be.
-The infrared camera provides a limited visualization
of some of the ways that COVID-19
could spread in real time.
As Americans struggle to contain this deadly pandemic,
and enter a season that celebrates
the very activities that foster community spread,
what we do to limit the virus' transmission
is a matter of life or death.