Environmental Pollution and Cardiovascular Disease: Part 1 of 2: Air Pollution

Abstract

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Over the past 50 years, there has been a substantial decline in the incidence of CVD and related mortality in high-income countries, largely due to the mitigation of modifiable risk factors such as smoking, hypertension, and diabetes. However, a significant burden of CVD remains in low- to middle-income countries, despite their lower prevalence of traditional risk factors; other environmental factors, particularly pollution, play a significant role in this attributable risk. Mounting evidence underscores a strong association between pollution and adverse health effects, including CVD. This article is part 1 of a 2-part state-of-the-art review and discusses air pollution and its adverse effects on CVD, highlighting pathophysiological mechanisms and methods to reduce air pollution and exposure to these pollutants.

Keywords: air pollution; global burden of disease; particulate matter.

Graphical abstract

Figure 1

Mortality From Cardiovascular Disease Cardiovascular disease (CVD) rates are higher in low- and middle-income countries (such as India and China) than in high-income countries (eg, the United States), with a significant surge in CVD rates in developing countries over the past 2 decades relative to the United States (data from Global Burden of Disease 2019⁹).

Figure 2

Air Pollution and Cardiovascular Disease (A) The percentage shift in overall mortality from 2010 to 2019 caused by PM_2.5 in the 20 most populous countries worldwide, with the increase in mortality mainly being seen in developing countries, whereas most developed countries show a decrease in PM_2.5-attributable mortality. (B) The distribution of disability-adjusted life years (DALYs) from noncommunicable diseases linked to PM pollution globally in 2019, with the majority of PM-attributable DALYs being due to CVD. (C) The proportion of cardiovascular disease DALYs caused by air pollution compared to other risk factors in 2019. Shown in red bars is the contribution of air pollution due to both ambient air PM pollution as well as household air pollution arising from the burning of solid fuels. Finally, (D) exhibits the global distribution of number of deaths in 2019 attributed to PM_2.5 air pollution per country. Data in all panels are adapted from Global Burden of Disease 2019. PM = particulate matter.

Figure 3

Global Ranking of Risk Factors Contributing to All-Cause Mortality in 2019 Global estimates of attributable deaths due to various risk factors indicate that environmental risk factors (shown in the red bars), especially air and water pollution and climate change, contributed significantly to global mortality. Data sourced from Global Burden of Disease 2019.

Figure 4

Mechanisms Underlying PM-Induced Cardiovascular Disease Inhaled PM localizes within pulmonary tissues, eliciting oxidative stress and systemic inflammation. This in turn triggers secondary effector pathways including the activation of the HPA axis, platelet activation, autonomic dysfunction, and the generation of biological intermediates such as modified phospholipids. These pathways result in endothelial and vascular injury, atherothrombosis, inflammation, epigenomic changes, and ultimately lead to the development of cardiovascular disease. HPA = hypothalamic-pituitary-adrenal.

Central Illustration

Pollution and Cardiovascular Disease Exposure to environmental pollutants occurs through various routes, leading to localized endothelial dysfunction and systemic inflammation. This inflammation activates prothrombotic pathways, the hypothalamic-pituitary-adrenal axis, and causes autonomic dysfunction, which in turn leads to oxidative stress, platelet activation, increased arterial inflammation, and cellular signaling abnormalities. Collectively, these insults result in the development of hypertension, atherothrombosis, altered glucose metabolism, and plaque instability, leading to adverse cardiovascular outcomes such as myocardial infarction, arrhythmias, and heart failure.