Researchers who study
tiny aerosols are concerned that the role of these particles is being
downplayed in public health communication.
Kat
Eschner July 7, 2020
Virologists and other
scientific experts still know relatively little about SARS-CoV-2, the virus
that causes COVID-19. But the ever-growing body of evidence about how the virus
is transmitted suggests that tiny airborne particles, commonly known as
aerosols, play a big role in spreading the microbe around. Researchers who
study this area are concerned that the role of these aerosols is being
downplayed in public health communication. This affects the recommendations
public health officials are giving out in regards to how individuals and larger
systems should be changing their behaviors as the pandemic continues to spread.
The message that people
need to stay at least six feet apart has become entrenched in public health
guidance. But that’s not enough, says Shelly Miller, a professor of mechanical
engineering at the University of Colorado Boulder. “We need a universal
strategy to help our businesses ensure good ventilation,” she says. “We need a
universal strategy to make sure people are wearing masks indoors and
appropriately reducing occupancy in indoor spaces.”
Miller is among the 239 scientists
who signed their name to a letter calling for governments—including international
bodies like the World Health Organization—to acknowledge and plan for
COVID-19′s airborne spread. Based on a review of existing literature, they say,
“there is significant potential for inhalation exposure to viruses in
microscopic respiratory droplets… at short to medium distances.” In other
words, the coronavirus can spread through the air from one person to another
without anyone needing to cough or sneeze—and it can go farther than the large
droplets produced by coughing or sneezing. This exposure can happen at room
scale, they write, which is ample reason to worry about people even further
away than a mere six feet.
“We want people to
understand why wearing masks is important, why less people indoors is
important, why good ventilation is important,” Miller says. “All of these
things together will help reduce our risk of getting sick.”
The CDC broadly
acknowledges that airborne droplets may be infectious, and wearing masks and
social distancing can provide protection. But getting the World Health
Organization to acknowledge the infectious potential of tiny aerosols in its
guidelines is proving more complicated, writes Apoorva Mandavilli in The New York
Times.
The WHO’s opinion is that
the primary method of spreading SARS-CoV-2 is via large droplets, which can’t
travel as far and are created by coughing or sneezing, something most are now
careful to avoid doing near others. As of their most recent guidelines, released June 29, they
continue to advise that tiny aerosols are an issue only in medical settings like the
dentist, Mandavilli writes.
The evidence that Miller
and her colleagues put forth strongly suggests that aerosols are a problem even
in everyday settings. In particular, six factors, she says, affect the presence
of these aerosols and the risk of SARS-CoV-2 transmission in a given setting:
whether it’s indoors or outdoors, whether it’s crowded, the quality of
ventilation, the amount of time people are in the space together, if people are
wearing masks, and whether people are singing or talking loudly. In general,
outdoor spaces, less crowded spots (both indoor and outside), better
ventilation, less time together, wearing masks, and avoiding spewing particles
through yelling or singing, all play a key role in containing the spread of the
novel virus.
“The main mode of
transmission of this virus is airborne and masks are the best protections that
we have right now,” says Emanuel Goldman, a Rutgers University microbiologist
who recently published a commentary on the decreased likelihood of SARS-CoV-2
being spread on surfaces. Goldman says “the data isn’t there yet” to firmly
establish the relationship between different kinds of respiratory droplets and
transmission. But he’s been wearing a mask since before it was recommended by
the CDC and he plans to keep wearing one.
No comments:
Post a Comment