Clean Air, Smart Cities, Healthy Hearts: Action on Air Pollution for Cardiovascular Health

The Dark Triad of Particulate Matter, Oxidative Stress and Coronary Artery Disease: What About the Antioxidant Therapeutic Potential

Particulate matter (PM) is a complex mixture of particles with different adverse effects on health, especially on the cardiovascular (CV) risk and disease (e.g., increased risk of total and CV mortality, ischemic heart disease, heart failure, stroke, hypertension, dyslipidemia and type 2 diabetes). Since oxidative stress (OS) and inflammation are the main key mechanisms by which PM exerted its biological effects on health, several oxidative and inflammatory-related biomarkers have been measured and associated with PM; abnormalities in these parameters in relation to PM highlight the key role of this relationship in terms of adverse health effects, including CV conditions. Antioxidant strategies might prevent/reverse, almost partly, CV effects related to PM exposure, by addressing OS and inflammation, although the clinical gain of these interventional tools is not yet clearly demonstrated. This review aims to summarize PM source and composition, discussing OS and inflammatory events associated with environmental PM exposure as key mechanistic determinants of CV risk and acute event precipitation. Moreover, the modifying potential of antioxidants, especially in subjects more susceptible to the adverse effects of air pollution and/or more highly exposed, will be discussed as a promising research area beyond conventional strategies actually available to prevent the harmful effects of PM (e.g., reduction of pollution sources and population exposure, assessment of air quality standards) in order to better face this dark triad composed of PM, OS and CV disease.

Cardiovascular disease in low- and middle-income countries associated with environmental factors

There is a growing recognition that the profound environmental changes that have occurred over the past century pose threats to human health. Many of these environmental factors, including air pollution, noise pollution, as well as exposure to metals such as arsenic, cadmium, lead, and other metals, are particularly detrimental to the cardiovascular health of people living in low-to-middle income countries (LMICs). Low-to-middle income countries are likely to be disproportionally burdened by cardiovascular diseases provoked by environmental factors. Moreover, they have the least capacity to address the core drivers and consequences of this phenomenon. This review summarizes the impact of environmental factors such as climate change, air pollution, and metal exposure on the cardiovascular system, and how these specifically affect people living in LMICs. It also outlines how behaviour changes and interventions that reduce environmental pollution would have significant effects on the cardiovascular health of those from LMICs, and globally.

Particulate Matter Air Pollution is a Significant Risk Factor for Cardiovascular Disease

Air pollution is responsible worldwide for 9-12 million deaths annually. The major contributor to air pollution is particulate matter ≤2.5 µg per cubic meter of air (PM2.5) from vehicles, industrial emissions, and wildfire smoke. United States ambient air standards recommend annual average PM2.5 concentrations of ≤12 μg/m³ while European standards allow an average annual PM2.5 concentration of ≤20 μg/m3. However, significant PM2.5 cardiovascular and pulmonary health risks exist below these concentrations. Chronic PM2.5 exposure significantly increases major cardiovascular and pulmonary event risks in Americans by 8 to more than 20% for each 10-μg/m3 increase in PM2.5. PM2.5-induced increases in lipid peroxidation, induction of vascular inflammation and endothelial cell injury initiate and propagate respiratory diseases, coronary and carotid atherosclerosis. PM2.5 can cause atherosclerotic vascular plaque rupture and myocardial infarction and stroke by activating metalloproteinases. This article discusses PM2.5 effects on the cardiovascular and pulmonary systems, specific PM2.5 pathophysiologic mechanisms contributing to cardiopulmonary disease, and preventive measures to limit the cardiovascular and pulmonary effects of PM2.5.

Residential Greenness and Long-term Mortality Among Patients Who Underwent Coronary Artery Bypass Graft Surgery

BACKGROUND

Studies have reported inverse associations between exposure to residential greenness and mortality. Greenness has also been associated with better surgical recovery. However, studies have had small sample sizes and have been restricted to clinical settings. We investigated the association between exposure to residential greenness and all-cause mortality among a cohort of cardiac patients who underwent coronary artery bypass graft (CABG) surgery.

METHODS

We studied this cohort of 3,128 CABG patients between 2004 and 2009 at seven cardiothoracic departments in Israel and followed patients until death or 1st May 2021. We collected covariate information at the time of surgery and calculated the patient-level average normalized difference vegetation index (NDVI) over the entire follow-up in a 300 m buffer from the home address. We used Cox proportional hazards regression models to estimate associations between greenness and death, adjusting for age, sex, origin, socioeconomic status, type of hospital admission, peripherality, air pollution, and distance from the sea.

RESULTS

Mean age at surgery was 63.8 ± 10.6 for men and 69.5 ± 10.0 for women. During an average of 12.1 years of follow-up (37,912 person-years), 1,442 (46%) patients died. A fully adjusted Cox proportional hazards model estimated a 7% lower risk of mortality (HR: 0.93, 95% CI = [0.85, 1.00]) per 1 interquartile range width increase (0.04) in NDVI. Results were robust to the use of different buffer sizes (100 m-1,250 m from the home) and to the use of average NDVI exposure during the first versus the last 2 years of follow-up.

CONCLUSIONS

Residential greenness was associated with lower risk of mortality in CABG patients.

Relationship between air quality and asthma-related emergency hospital admissions in Mexico City 2017-2019

BACKGROUND

Previous studies found exposure to air pollution leads to exacerbations of asthma in paediatric and adult patients and increases asthma-related emergency hospital admissions (AREHA).

METHODS

AREHAs and levels of air pollutants (PM10, PM2.5 and NO2) were obtained from Mexico City for the period 2017-2019. A time-series approach was used to explore the relationship between air pollutants and AREHA. Relative risks of AREHA were estimated using a negative binomial regression in young children (less than 5 years) and adults (greater than 18 years).

RESULTS

There was a positive association between AREHA and PM10, PM2.5 and NO2 in adults, which remained after mutual adjustment for these pollutants. The relative risk (RR) of admission in adults increased by 3% (95% CI 1% to 4%) for a 10 µg/m3 increase in PM10, 1% (0.03% to 3%) for a 5 µg/m3 increase in PM2.5 and by 1% (0.06% to 2%) for a 5 µg/m3 increase in NO2. In contrast, in young children, AREHAs were negatively associated with PM10 after adjustment for NO2 (RR 0.97 (0.95 to 0.99) for a 10 µg/m3 and with NO2 after adjustment for PM10 and PM2.5 (RR 0.98 (0.96 to 0.99) and 0.97 (0.96 to 0.99), respectively, for a 5 µg/m3 increase in NO2). AREHAs in children were not associated with PM2.5 after adjustment for NO2.

CONCLUSIONS

Ambient air pollution, within the previous week, was associated with emergency hospital admissions for asthma to public hospitals in adults in Mexico City. The relationship in children was less consistent. Further work is needed to explore why differences between adults and children exist to inform appropriate interventions to benefit public health.

Effects of short-term waterfall forest aerosol air exposure on rat lung proteomics

Background

Chronic exposure to airborne microparticles has been shown to increase the incidence of several chronic diseases. Previous studies have found that waterfall forest aerosols contribute to a diminished immune stress response in patients with asthma. However, the specific effects of short-term waterfall forest aerosol exposure on lung proteins have not been fully elucidated.

Methods

This study used liquid chromatography-tandem mass spectrometry (LC-MS) to analyze changes in protein expression in the lungs of rats exposed to short-term waterfall forest aerosol environments. Specific protein markers were identified using bioconductivity analysis screening and validated using immunohistochemistry.

Results

Waterfall forest aerosol environment exposure on day 5 downregulated the expression of the classical inflammatory pathway nuclear factor κB (NF-κB) signaling pathway. As the waterfall forest aerosol environment increased due to the duration of exposure, it was involved in oxidative phosphorylation and then hormone signaling in lung cells from the very beginning. In contrast, at day 15 of exposure, there is an effect on the regulation of the immune-related high-affinity IgE receptor pathway. In addition, iron-sulfur Rieske protein (Uqcrfs1), mitochondrial Tu translation elongation factor (Tufm) and ribosomal protein L4 (Rpl4) were identified as possible bioindicators for the evaluation of air quality.

Conclusions

These results provide a comprehensive proteomic analysis that supports the positive contribution of a good air quality environment to lung health.