Review articleAir particulate matter and cardiovascular disease: A narrative review
Introduction
In December 1952, the Great Smog event in London [1], [2] attracted the attention of both the scientific community and politic governments on the potentially massive influence of air pollution on human health. As a consequence of stagnant weather conditions, there was a severe increase in the concentration of air pollutants. Over the next several days, mortality in the general population was more than three-fold times than expected, leading to an estimated excess of 4000 deaths [3]. Since this historical air pollution episode, a large number of studies have confirmed the association of air pollution with human diseases, which was not confined to respiratory illnesses, but also involved many other conditions with the highest impact on cancer and cardiovascular diseases (CVD). Of note, the World Health Report 2002 by the World Health Organization (WHO) estimated that each year about 800,000 premature deaths are due to air pollution worldwide [4]. Both gaseous and particulate matter (PM) air pollutants have been found to be harmful for human health. However, PM initially appeared as the most detrimental, becoming the most investigated pollutants with particular interest regarding CVD [5]. Indeed, high concentrations of PM have been associated with cardiovascular morbidity and mortality in both short- and long-term epidemiological studies. Moreover, many plausible pathophysiological mechanisms have been proposed to explain the link between PM and cardiovascular disease [6]. In this review we summarize the main recent findings on the impact of PM air pollution on CVD and also consider new, potentially interesting, concepts regarding the quality of PM rather than merely its concentration.
Section snippets
PM: what is? How is it measured?
PM is defined as material suspended in the air in the form of minute solid particles or liquid droplets, usually considered as an atmospheric pollutant with significant impact on human health. These airborne particles have been traditionally characterized by measurement of PM with aerodynamic diameter less than 10 μm in diameter (PM10), because particles of this size can penetrate into the airways where they may exert adverse effects. Remarkably, pathogenic properties of PM10 appears to be
Epidemiological studies linking PM and CVD
CVD is the leading cause of morbidity and mortality in Western countries, which are also characterized by high level of air pollution. Since 2004, the American Heart Association (AHA) recognized that exposure to high concentration of PM is associated with an increased risk for cardiovascular events, particularly myocardial infarction (MI), stroke, arrhythmias, and heart failure [12]. During the last decade, further evidence in this direction has progressively accumulated, so that the updated
Pathophysiological mechanisms linking PM and CVD
Several PM-related mechanisms have been shown to play a role in pathways leading to CVD (for a comprehensive review see [11]). Three main mechanisms have been recognized to foster extrapulmonary effects on cardiovascular system: I) release of pro-inflammatory and vasoactive mediators from PM-stimulated cells of the lung; II) influence on autonomic nervous system induced by PM interactions with lung receptors; and III) direct translocation of PM, in particular ultrafine particles (< 0.1 μm), into
What kind of PM? Not only dimension (aerodynamic diameter), but also quality (components)
The studies linking PM to human diseases have usually recognized the finest particles as the main culprit of PM-related harmful effects. This theory is consistent with the large majority of epidemiological and biological investigations, which suggested a predominant role of PM2.5 in cardiovascular mortality and morbidity, while coarse PM10-2.5 particles received less attention and emphasis [11]. Actually, the associations of PM10-2.5 with either overall or cardiovascular mortality were
Are all the people equally susceptible to PM harmful effects?
Several studies have suggested that some groups of subjects are specifically susceptible to the harmful effects triggered by PM exposure. Susceptible populations include elderly subjects, diabetic patients, and individuals with known coronary artery disease [11]. In particular, as mentioned above, in an angiographically-controlled study only subjects with documented coronary artery disease showed a significant association between PM air pollution and new cardiovascular events, thus supporting
Not only PM. Do the other air pollutants have a significant role?
Experimental and epidemiological studies have showed that, beyond PM, many other air pollutants, including gaseous pollutants like carbon monoxide, nitrogen dioxide, sulfur dioxide, and ozone, are linked with adverse cardiovascular responses (Fig. 1) [80], [81]. A very recent meta-analysis, which finally included 34 out of 117 screened studies, has found that PM10, PM2.5, carbon monoxide, nitrogen dioxide, and sulfur dioxide (but not ozone) were all significantly associated with MI risk.
Reducing PM exposure at population level: a proof of principle of cardiovascular toxicity
As for any other “risk factor” emerging from association studies, a crucial question is represented by actual proof of causality. Notwithstanding the biological plausibility of PM-induced harmful effects outlined above, causality can be definitively established only through interventional studies showing that the reduction of the risk factor is followed by a decrease in disease burden. Until recently, only few studies have investigated the efficacy of public health interventions aiming to
Publication bias in environmental health studies
Although the relationship between air pollution and cardiovascular disease appears sufficiently solid, the potential publication bias in environmental health studies needs to be taken into account. In the case of air pollution, indeed, studies with evidence of significant positive associations have likely more chance of publication than the negative ones. [31], [32], [33], [34], [35], [36]. Actually, it has been estimated that the association between air pollution and various health outcomes
Conclusions
In summary, a broad range of experimental and epidemiological evidences convincingly supports the detrimental role of PM on cardiovascular morbidity and mortality [5], [6], [11]. Both short- and long-term exposure to PM, mainly PM2.5, have been associated to CVD risk in terms of either hospital admissions or fatal events, with particularly evident impact on the latter. Long-term exposure appears to increase the risk for cardiovascular mortality to a greater extent than short-term exposure. The
Learning points
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A broad range of experimental and epidemiological evidences consistently supports the detrimental role of both short- and long-term exposure to particulate matter (PM) on cardiovascular morbidity and mortality. Causality has been recently strongly supported by observations showing reduced cardiovascular risk after coordinated policies resulting in lowering PM exposure at population level.
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Although the PM-related risk for a single individual appears relatively low, the PM-related population
Conflict of interests
None of the authors had a personal or financial conflict of interest.
References (91)
- et al.
Air pollution and health
Lancet
(2002) - et al.
Air pollution and cardiovascular disease
Thromb Res
(2012) - et al.
Thrombogenicity and cardiovascular effects of ambient air pollution
Blood
(2011) - et al.
Public health importance of triggers of myocardial infarction: a comparative risk assessment
Lancet
(2011) - et al.
Particulate air pollution and hospital admissions for congestive heart failure in seven United States cities
Am J Cardiol
(2006) - et al.
Air pollution and hospitalization for venous thromboembolic disease in Chile
J Thromb Haemost
(2010) Fine particulate: it matters
J Thromb Haemost
(2010)- et al.
Traffic exposure and incident venous thromboembolism in the atherosclerosis risk in communities (ARIC) study
J Thromb Haemost
(2011) - et al.
TLR-2 is involved in airway epithelial cell response to air pollution particles
Toxicol Appl Pharmacol
(2005) - et al.
Particulate matter initiates inflammatory cytokine release by activation of capsaicin and acid receptors in a human bronchial epithelial cell line
Toxicol Appl Pharmacol
(1999)
Effects of inhalable particulate matter on blood coagulation
J Thromb Haemost
Air pollution-associated procoagulant changes: the role of circulating microvesicles
J Thromb Haemost
Inflammation and thrombosis
J Thromb Haemost
PM-induced cardiac oxidative stress and dysfunction are mediated by autonomic stimulation
Biochim Biophys Acta
Gene-air pollution interactions and cardiovascular disease: a review
Prog Cardiovasc Dis
The biological effect of endogenous sulfur dioxide in the cardiovascular system
Eur J Pharmacol
Cardiorespiratory and all-cause mortality after restrictions on sulphur content of fuel in Hong Kong: an intervention study
Lancet
Effect of air-pollution control on death rates in Dublin, Ireland: an intervention study
Lancet
Air pollution and the London fog of December, 1952
J R Sanit Inst
Mortality from fog in London
Br Med J
The world health report 2002 – reducing risks, promoting healthy life
Epidemiological evidence of effects of coarse airborne particles on health
Eur Respir J
Comparison of particle lung doses from the fine and coarse fractions of urban PM-10 aerosols
Inhal Toxicol
An association between air pollution and mortality in six U.S. cities
N Engl J Med
Particulate air pollution as a predictor of mortality in a prospective study of U.S. adults
Am J Respir Crit Care Med
Particulate Matter air pollution and cardiovascular disease. An update to the scientific statement from the American Heart Association
Circulation
Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association
Circulation
Acute and chronic effects of particles on hospital admissions in New-England
PLoS One
Estimating the population attributable risk for multiple risk factors using case–control data
Am J Epidemiol
The effect of fine and coarse particulate air pollution on mortality: a national analysis
Environ Health Perspect
Fine particulate air pollution and hospital admission for cardiovascular and respiratory diseases
JAMA
Chronic particulate exposure, mortality, and coronary heart disease in the nurses' health study
Am J Epidemiol
Exposure to traffic and the onset of myocardial infarction
N Engl J Med
Ischemic heart disease events triggered by short-term exposure to fine particulate air pollution
Circulation
Cardiovascular mortality and long-term exposure to particulate air pollution: epidemiological evidence of general pathophysiological pathways of disease
Circulation
Long-term exposure to outdoor air pollution and incidence of cardiovascular diseases
Epidemiology
Long-term exposure to air pollution and incidence of cardiovascular events in women
N Engl J Med
Air pollution and hospital admissions for ischemic and hemorrhagic stroke among medicare beneficiaries
Stroke
Exposure to particulate air pollution and cognitive decline in older women
Arch Intern Med
Exposure to particulate air pollution and risk of deep vein thrombosis
Arch Intern Med
Access rate to the emergency department for venous thromboembolism in relationship with coarse and fine particulate matter air pollution
PLoS One
Ambient particulate matter air pollution and venous thromboembolism in the Women's Health Initiative Hormone Therapy trials
Environ Health Perspect
Exposure to ambient fine particulate matter and primary cardiac arrest among persons with and without clinically recognized heart disease
Am J Epidemiol
A panel study of air pollution in subjects with heart failure: negative results in treated patients
Occup Environ Med
Investigators of the Registry of Canadian Stroke Network. Fine particulate air pollution (PM2.5) and the risk of acute ischemic stroke
Epidemiology
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