Running in Polluted Air Is a Two-edged Sword

Physical Exercise in Low Air Pollution Areas Is Cardioprotective But Detrimental for the Heart in High Air Pollution Areas

Thomas Münzel; Omar Hahad; Andreas Daiber


Eur Heart J. 2021;42(25):2498-2500. 

In This Article

By Which Mechanism Does Air Pollution Cause Adverse Health Effects and Neutralize Protective Mechanisms Induced By Regular Exercise?

Particulate matter (and other air pollution constituents such as reactive gases) causes recruitment of immune cells, increases oxidative stress in the vasculature and the brain, and leads to a supersensitivity of the vasculature to vasoconstricting agents, all of which contribute to vascular (endothelial) dysfunction.[11] Accordingly, particulate matter leads to subclinical, and later to full-blown, atherosclerotic and cardiometabolic disease, sharing pathomechanisms with classical cardiovascular risk factors such as hypertension or diabetes. In addition, particulate matter activates the hypothalamic–pituitary–adrenal axis and the sympathetic system, thereby triggering the release of stress hormones such as cortisol and catecholamines.[12] Of note, ultrafine particles can even cross the blood–brain barrier, thereby causing cerebral (hypothalamic) inflammation and a direct activation of the sympathetic nervous system.[13] Physical exercise may counteract these detrimental effects of air pollution by its well-known cardioprotective effects involving activation of the AMP-activated protein kinase and protective transcription factors such as NRF2 and PGC-1α that largely improve mitochondrial biogenesis/function and metabolism/energy use, as well as induction of endothelial nitric oxide synthase activity and nitric oxide signalling by shear stress, all of which mimic pre-conditioning-like protective effects with improved antioxidant and anti-inflammatory defence.[14,15]