Page 46 - Green Builder May-June 2020 Issue

Virus How Contagious Is That Disease?

APPROXIMATE REPRODUCTION NUMBER (RO)

Filtration Measles

Smallpox
Requires SARS SOURCES: WORLD HEALTH ORGANIZATION, CENTERS FOR DISEASE CONTROL, KING SAUD UNIVERSITY, NATURE

Covid-19
Overlapping Ebola

Seasonal influenza
Technologies MERS

0 3 6 9 12 15

Effectively Reality check. COVID-19 falls somewhere in the middle of other deadly diseases, in terms of how
easy it is to spread.
removing viral BY MATT POWER

particles from your OU’RE PROBABLY WONDER-
ING if your HEPA or MERV air
filters will protect you and your
home atmosphere family from spreading corona-
Y virus around the house.
is tricky. Success In short, the answer is “not always.” The
problem is that no filter removes 100 percent
depends on the of viral particles, 100 percent of the time.
That doesn’t mean they don’t help. Good fil-
speed of airflow, ters, especially when tied to your forced-air
furnace or central air conditioning, greatly
filter size, dispersion reduce the number of pathogens floating
around your home. But anything less than
and a little luck. 100 percent is still a risk. According to a
report in Science Daily, a single virus par-
ticle is enough to infect someone—and lead
to full-blown symptoms.
Let’s look at what are probably the two
best filtration technologies for home use,
other than ultraviolet light: HEPA and
MERV filters.
HEPA—According to American research-
ers, HEPA filters may not provide adequate
protection for all threats because viruses are
submicron in size and have small minimum CREDIT: HOME AIR QUALITY GUIDES/FLICKR
infections doses (MID50). Thus, an appropri-
ate viral challenge “may yield penetration
that will lead to infection of personnel.”
MERV—Several factors impact how well Room for improvement. HEPA filters may not
MERV filters work, including the specific provide adequate protection for all threats because
rating of the filter (higher is better). For viruses are submicron in size and have small
example, with MERV filters, the speed of minimum infections doses.

40 GREEN BUILDER May/June 2020 www.greenbuildermedia.com

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