The particulate matter from wildfire smoke may be arduous to spot – with
the eyes – within days, but those perilous particles continue to post
health risks for up to 3 months after exposure, new research suggested.
A
study
published in
epidemiology
in late May demonstrated that fine particulate matter in wildfire smoke
represents a danger to human health considerably longer than a couple of
days as previously thought. Researchers also found that exposure to the
particulate matter can occur even after the fires have ended.
Because
studies have shown
that air pollution exposure can trigger heart attack within an hour, the
duration of the effects of wildfire particulate matter surfaced by this new
research is a key new insight.
The study, authored by researchers from the Icahn School of Medicine at
Mount Sinai in New York City and Harvard T.H.Chan School of public Health
in Boston, highlighted increased risks for patients with cardiovascular
disease (CVD) when exposed to smoke particulate matter, referred to as
PM2.5, which by definition is 2.5 microns in diameter. To get an idea of
how small the particles in wildfire smoke are, the average human hair is
about 70 microns in diameter, meaning a 2.5-micron particle is about 28
times smaller than a human hair.
The study showed that this tiny irritant is dangerous to those with ischemic
heart disease, arrhythmia, and hypertension, as well as people with a
number of cardiorespiratory diseases.
Researchers made these conclusions by obtaining hospitalization records for
the residents of 15 states between 2006 and 2016 from the State Inpatient
Databases as well as daily smoke particulate matter estimates at 10 km
2
cells across the contiguous US, and aggregating them using zip codes to
match the spatial resolution of the hospital records. The 3-month exposure
to smoke particulate matter was associated or marginally associated with
increased hospitalization risks for most cardiorespiratory diseases, with
hypertension showing the greatest susceptibility.
“Patients with CVD and the general public should be aware that wildfire
smoke is a serious health risk, even if the fire is far away from your
home. This is because the emissions can remain in the air and travel long
distances for weeks or months after a wildfire has ended,” said yaguang Wei,
PhD, assistant professor at the Icahn School of Medicine at Mount Sinai and
principal investigator of the study. “Cardiologists and other healthcare
providers should definitely discuss these risks with their patients,not
only during wildfires but also in the following weeks,as the risk may
persist.”
Wei said that ongoing studies show that the particulate matter in wildfire
smoke is among the most toxic environmental pollutants and can do systemic
damage, which can pose further complications for those battling CVD.
Yaguang Wei, PhD
“This is because smoke has smaller particles, which can more easily get into
the body, and it has more carbonaceous compounds, which are thought to be
especially toxic,” Wei said. “They can enter the bloodstream and circulate
throughout the body, which generates systematic effects. The emissions can
remain in the air and travel long distances for weeks or months after a
wildfire has ended.”
Loren Wold, PhD, a professor at the Ohio State University College of
Medicine, Columbus, Ohio, said that this study is crucial, in that it is indeed
critically important to understand the health implications of this particulate matter
given the increasing occurrence of wildfires worldwide, and that particulate
matter is not very extensively studied.
“People with cardiovascular disease should be especially careful being
outside during days when wildfire smoke is present, as exposure to
particulate matter from wildfire smoke is especially dangerous for those
with cardiovascular disease as it causes an increase in oxidative stress and
inflammation, which can further worsen the disease,” Wold, who has been
studying particulate matter himself for two decades, said. “Wildfire smoke
can also cause temporarily increased blood pressure and vascular
inflammation, as well as changes in heart rate variability, which can
further exacerbate cardiovascular disease.”
Particulate matter this small can bypass the nose and throat and enter deep
into the lungs, and “penetrate the linings of blood vessels to gain entry to
the circulation,” Wold said. It also contains higher concentrations of
organic carbon and black carbon, or soot, and can travel thousands of miles
and linger for weeks in the atmosphere, he said.
Plus, he said, the scale and unpredictability of exposure to wildfire
particulate matter makes the health risks “especially troublesome.”
Shahir Masri, ScD, an associate specialist in air pollution exposure
assessment and epidemiology at the Irvine Joe C.wen School of Population &
Public Health, University of California, Irvine, California, said that the
notable finding of this study is the duration of the effects posed by the
wildfire smoke particulate matter. He pointed out this
review paper from 2024
that highlighted its many negative effects, while arguing that the
dangerous pollutants that come from wildfires come from other sources, too.
“Many pollutants originate from wildfires, such as carbon monoxide, nitrogen
oxides, and polycyclic aromatic hydrocarbons. However, I should mention that
these pollutants shouldn’t be thought of as exclusively
wildfire-related,” he said.
Instead, they’re common byproducts from the combustion of organic matter,
whether it be wildfires or vehicle exhaust, Masri said. “Also, even acute,
or short-term exposure, to wildfire pollution, is known to exacerbate the
symptoms related to underlying health conditions, including cardiovascular
disease, and also asthma, COPD [ chronic obstructive pulmonary disease]and
lung cancer, and others mentioned in the new harvard study.”
At-Risk Individuals Should Take Care
the take-home from this study is that individuals suffering from CVD, as
well as other underlying conditions, should protect themselves against the
effects of wildfire smoke particulate matter when it’s in the air. That
includes both immediate, acute exposure as well as follow-on exposure,
which this study shows can linger for up to 3 months after the event.
The first key is for impacted individuals to stay aware of when the
particulate matter is in the air. The US government provides an air quality
tool called
Air Nowwhere
users can look up their local air forecast with their zip code or city and
state. The meter on this page displays the Air Quality Index (AQI).
Government guidelines
suggest that if results show that if the AQI is between 101 and 150, those
with CVD or other underlying conditions should reduce prolonged or heavy
outdoor exertion; if it’s over 201, all outdoor exertion should be avoided;
and if over 301, all physical activity outdoors should be avoided.
Shahir Masri, SCD
Wei said that the first thing individuals with CVD should use to protect
against the complications from wildfire particulate matter is an air purifier
with a high efficiency particulate air filter and noted that these are
becoming more inexpensive. Masri agreed that air purifiers are essential to
help with indoor air quality and provided some tips on successful use.
“Running an air purifier can be very effective at reducing levels of PM2.5
in the home and workspace by 50% or more. Air purifiers, however, come
with different flow rates and (effective) sizes. One must be sure to read
the label of the air purifier to understand the size of the room it is
capable of cleaning,” Masri said. “If you only have one air purifier, to
ensure the cleanest air I suggest placing it in the room where you sleep or
work during the day and closing the doors and windows to that room. This
reduces intrusion of dirty outdoor air during a wildfire, for instance, and
therefore enables the device to do its job more effectively.”
Masking is also an option,Masri said,but only when it’s the right mask,
worn properly.
