JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
VOL. 65, NO. 21, 2015
ª 2015 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 0735-1097/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jacc.2015.04.010
EDITORIAL COMMENT
Personalizing Your Airspace and Your Health* Sanjay Rajagopalan, MD,y Robert D. Brook, MDz
I
ndoor and outdoor air pollution rank as the
and point to an increase in the proportion of
fourth and ninth leading causes of global
patients in East Asia living above the World Health
morbidity and mortality in the most recent
Organization (WHO) interim Target-1 of 35 mg/m 3
Global Burden of Disease (GBD) report and collec-
(increased from 51% in 1998 to 2000 to 70% in
tively outrank other major risk factors in terms of
2010 to 2012) (5). In stark contrast in North America,
importance (1). The fine particulate matter 48 h, among 35 healthy young
ficantly
university students in Shanghai, China. The chosen
measured indoor PM2.5 levels across both exposure
location is a strength of the study, being conducted in
scenarios, lending further credence to a prob-
a very polluted part of the world, with average levels
able causal exposure–health response relationship.
of 103 mg/m 3. Active air filtration proved capable of
Though changes in gaseous pollutants did not likely
reducing indoor PM2.5 concentration by just more
confound the main results, as they were thought not
linearly
associated
with
the
directly
than one-half, from 96.2 to 41.3 mg/m 3. After 48 h of
to be altered by filtration, their levels were not
“cleaner air” exposure, systolic and diastolic blood
evaluated.
pressure fell, whereas a few of the measured metrics
concomitant reduction in these copollutants could
of inflammation (MCP-1, interleukin-1b, myeloper-
provide further or differing health benefits. The spe-
oxidase) and platelet activation (sCD40L) were
cific sources (e.g., traffic, coal-fired power plants),
It
thus
remains
unclear
whether
a
significantly reduced. Several other biomarkers also
particle sizes (fine vs. ultrafine ranges), and compo-
trended towards improvement, but were not signifi-
nents (organic/elemental carbon, sulfates, metals)
cantly changed. Fractional exhaled nitric oxide, an
most strongly linked to the health effects also were
established marker of respiratory inflammation, was
not reported.
reduced, but lung function measured by spirometry
Although improvement in outdoor air quality ul-
did not change, possibly owing to the short-term
timately will be needed to change indoor air quality
nature of the intervention. Added to the results
in the cities of China and India, when rapid changes
from a few previous studies, these new findings
in outdoor air quality occur, as it did during the
bolster the evidence that improving indoor air filtra-
Beijing Olympics (PM 2.5 levels 101 and 84 m g/m 3
tion may be a practical “personalized” method to
before and after, averaging 69 m g/m 3 during the
reduce overall PM2.5 exposure and mitigate adverse
games), several biomarkers of inflammation throm-
health effects. The observed improvement in out-
bosis, as well as blood pressure, improved (11). The
comes, despite particulate levels remaining high
good news is that air quality regulations, when
during air filtration (41.3 mg/m 3) supports the pre-
enforced, can substantially reduce prevailing out-
vailing understanding of a log-linear dose–response
door air pollution concentrations and improve soci-
relationship between exposure and health effects,
etal life expectancy rates (12). In the meantime,
whereby any lowering of pollution can translate into
personalized
benefits with larger absolute benefits, the higher the
ventions to lower exposures (e.g., filters in homes
level of air pollution (2). The population was homo-
and cars) may be needed in order to optimally protect
geneous, taking no potentially confounding medica-
citizens in these areas (13).
behavioral
and
small-scale
inter-
tions, and residing within 2 nearby buildings, thus making for a clean study design. Assuming the
REPRINT REQUESTS AND CORRESPONDENCE: Dr.
participants complied with the protocol, potential
Sanjay Rajagopalan, Health Science Facility II, Divi-
confounding effects of lifestyle changes (e.g., diet,
sion of Cardiovascular Medicine, University of Mary-
activity), unmeasured environmental factors (e.g.,
land School of Medicine, 20 Penn Street, Baltimore,
traffic, noise, temperature), and PM2.5 exposure mis-
Maryland
classification(s) were all likely minimized. Most of
umaryland.edu.
21201.
E-mail:
srajagopalan@medicine.
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Air Pollution Prevention
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KEY WORDS air pollution, cardiovascular, environment, indoor air quality, inflammation