ASHRAE Journal - March 2022 - 46

RESIDENTIAL APPLICATIONS
Column
Wildfire Smoke Impacts
On Residential IAQ
BY CHRISSI ANTONOPOULOS, STUDENT MEMBER ASHRAE; STEVEN EMMERICH, FELLOW ASHRAE; BRETT SINGER, MEMBER ASHRAE; RICK KARG, LIFE MEMBER ASHRAE
Wildland fires are occurring with increased frequency and intensity throughout
many areas of the world, and wildfire smoke exposure is becoming a seasonal event
in many communities. Increases in property loss, illness and mortality are well documented.1-3
In 2020, over 58,000 wildfires occurred in the U.S. alone, burning more
than 10 million acres.4
Wildfire smoke is a toxic mixture with as much as
90% of the particle mass presenting as PM2.5.5,6 Wildfire
smoke also contains ultrafine particles, toxic particlephase
constituents and many irritant gases, including
acrolein, formaldehyde and organic acids.7 When fires
reach and burn buildings, the human-produced materials
add toxic constituents to the smoke, including
polychlorinated biphenyls (PCBs) and polybrominated
diphenyl ethers (PBDEs). A single wildfire event can
result in a large region experiencing levels of PM2.5 that
exceed national ambient air quality standards8 over
many days.9
Even without active filtration, sheltering in a building
can lower exposure to outdoor PM2.5 significantly
as particles deposit during air infiltration through
the building envelope and also deposit on surfaces
inside the occupied zone at rates that can be faster
than outdoor air change when mechanical ventilation
is temporarily turned down or turned off for smoke
protection. However, even with this level of protection,
the very high concentrations of outdoor PM2.5 that
occur during some smoke episodes will result in indoor
46
ASHRAE JOURNAL ashrae.o rg M A R CH 2022
concentrations greatly exceeding the 24 hour World
Health Organization exposure guideline of 15 µg/m3.10
Some chronic health conditions contribute to greater
susceptibility to wildfire smoke. These include respiratory
conditions such as asthma, COPD and bronchitis.11
Diseases of the circulatory system, including high blood
pressure and coronary artery disease, can be exacerbated
by fine particles and other air contaminants.11
Exposure to elevated levels of wildfire smoke specifically
has been linked to many adverse health outcomes.12-16
A recent study reported that PM2.5 from wildfires results
in larger increases in respiratory hospitalization rates
per 10 µg/m3 increase in ambient concentration than
non-wildfire PM2.5.17
Segments of the population in various life stages
are impacted differently by wildfire smoke hazards.
Chrissi Antonopoulos is a senior analyst at the Pacific Northwest National Laboratory.
Steven Emmerich is group leader of the indoor air quality and ventilation group at
the National Institute of Standards and Technology. Brett Singer is the head of the
sustainable energy and environmental systems department and co-lead of the indoor
environment group at Lawrence Berkeley National Laboratory. Rick Karg is president
of Residential Energy Dynamics, chair of the ASHRAE Residential Buildings Committee
and a voting member of SSPC62.2.
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ASHRAE Journal - March 2022

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