Long-term Ambient Fine Particulate Matter Air Pollution
and Lung Cancer in a Large Cohort of Never-Smokers
Michelle C. Turner1,2, Daniel Krewski2,3,4, C. Arden Pope, III5, Yue Chen3, Susan M. Gapstur6,
and Michael J. Thun6
1
Faculty of Graduate and Postdoctoral Studies, 2
McLaughlin Centre for Population Health Risk Assessment, Institute of Population Health, and 3
Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; 4
Risk Sciences
International, Ottawa, Ontario, Canada; 5
Department of Economics, Brigham Young University, Provo, Utah; and 6
Epidemiology Research Program,
American Cancer Society, Atlanta, Georgia
Rationale: There is compelling evidence that acute and chronic
exposure to ambient fine particulate matter (PM2.5) air pollution
increases cardiopulmonary mortality. However, the role of PM2.5 in
the etiology of lung cancer is less clear, particularly at concentrations
that prevail in developed countries and in never-smokers.
Objectives: This study examined the association between mean longterm
ambient PM2.5 concentrations and lung cancer mortality among
188,699 lifelong never-smokers drawn from the nearly 1.2 million
Cancer Prevention Study–II participants enrolled by the American
Cancer Society in 1982 and followed prospectively through 2008.
Methods: Mean metropolitan statistical area PM2.5 concentrations
were determined for each participant based on central monitoring
data. Cox proportional hazards regression models were used to estimate
multivariate adjusted hazard ratios and 95% confidence
intervals for lung cancer mortality in relation to PM2.5.
Measurements and Main Results: A total of 1,100 lung cancer deaths
were observed during the 26-year follow-up period. Each 10 mg/m3
increase in PM2.5 concentrations was associated with a 15–27% increase
in lung cancer mortality. The association between PM2.5 and
lung cancer mortality was similar in men and women and across
categories of attained age and educational attainment, but was
stronger in those with a normal body mass index and a history of
chronic lung disease at enrollment (P , 0.05).
Conclusions: The present findings strengthen the evidence that ambient
concentrations of PM2.5 measured in recent decades are associated
with small but measurable increases in lung cancer mortality.
Keywords: fine particulate matter air pollution; lung neoplasms;
never-smokers; asthma; pulmonary disease, chronic obstructive
Time-series and prospective studies provide compelling evidence
that acute and chronic exposure to ambient fine particulate
matter (PM2.5) air pollution is associated with increased
cardiopulmonary mortality (1). However, the role of PM2.5 in
the etiology of lung cancer is less clear, particularly at concentrations
that prevail in developed countries (z 5–35 mg/m3
) and
in never-smokers (2). In China, high levels of indoor air pollution
caused by coal and biomass burning contribute to high lung cancer
rates observed even among nonsmoking women (3). There
are also high background concentrations (.100 mg/m3
) of outdoor
air pollution in some industrial regions of the country (2).
Given the strong relationship between cigarette smoking and
lung cancer risk, evidence of an association between PM2.5 and
lung cancer is more convincing when observed among neversmokers,
compared with current or former smokers, because of
possible residual confounding by cigarette smoking (4, 5). A
previous analysis of the American Cancer Society Cancer Prevention
Study-II (CPS-II), based on 16 years of follow-up data
of approximately 500,000 included participants controlling for
measured parameters of active smoking, found an 8% (95%
confidence interval [CI], 1–16%) increase in lung cancer mortality
for each 10 mg/m3 increase in PM2.5 concentrations (6).
The risk was somewhat higher, although statistically insignifi-
cant, when restricted to the subgroup of never-smokers. An
extended analysis of the Harvard Six Cities Study (n ¼ 8,096)
found a positive association between PM2.5 and lung cancer
mortality (hazard ratio [HR] per each 10 mg/m3 ¼ 1.27; 95%
CI, 0.96–1.69) controlling for active smoking (7). Naess and
coworkers (8) observed significant positive associations between
PM2.5 and lung cancer mortality among Oslo women in a recent
register-based study; however, no data on smoking history were
available in this study.
Despite this, the World Health Organization has estimated that
long-term PM2.5 exposure is responsible for approximately 5% of
all cancers of the trachea, bronchus, and lung (9). To address the
potential for residual confounding by cigarette smoking status,
the present study examined associations between mean long-
(Received in original form June 10, 2011; accepted in final form September 16, 2011)
Supported by Canada Graduate Scholarship from the Canadian Institutes of
Health Research (M.C.T.). D.K. is the Natural Sciences and Engineering Research
Council Chair in Risk Science at the University of Ottawa.
Author Contributions: Conception and design, M.C.T., D.K., C.A.P., Y.C., S.M.G.,
and M.J.T.; analysis and interpretation, M.C.T., D.K., C.A.P., Y.C., S.M.G., and
M.J.T.; drafting the manuscript for important intellectual content, M.C.T., D.K.,
C.A.P., Y.C., S.M.G., and M.J.T.
Correspondence and requests for reprints should be addressed to Michelle
C. Turner, M.Sc., McLaughlin Centre for Population Health Risk Assessment,
Institute of Population Health, University of Ottawa, One Stewart Street, Room
313, Ottawa, ON, K1N 6N5 Canada. E-mail:
[email protected]This article has an online supplement, which is accessible from this issue’s table of
contents at www.atsjournals.org
Am J Respir Crit Care Med Vol 184. pp 1374–1381, 2011
Copyright ª 2011 by the American Thoracic Society
Originally Published in Press as DOI: 10.1164/rccm.201106-1011OC on October 6, 2011
Internet address: www.atsjournals.org
AT A GLANCE COMMENTARY
Scientific Knowledge on the Subject
There is compelling evidence that acute and chronic exposure
to ambient fine particulate matter (PM2.5) air pollution
increases cardiopulmonary mortality. However, the
role of PM2.5 in the etiology of lung cancer is less clear.
What This Study Adds to the Field
This study examined the association between mean longterm
ambient PM2.5 concentrations and lung cancer mortality
in a 26-year prospective study of a large cohort of
lifelong never-smokers. Each 10 mg/m3 increase in PM2.5
concentrations was associated with a 15–27% increase in
lung cancer mortality. These results strengthen the evidence
that ambient concentrations of PM2.5 are associated with
small but measurable increases in lung cancer mortality.