Abstract
BackgroundExposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask.MethodsIn an open-label cross-over randomised controlled trial, 15 healthy volunteers (median age 28 years) walked on a predefined city centre route in Beijing in the presence and absence of a highly efficient facemask. Personal exposure to ambient air pollution and exercise was assessed continuously using portable real-time monitors and global positional system tracking respectively. Cardiovascular effects were assessed by continuous 12-lead electrocardiographic and ambulatory blood pressure monitoring.ResultsAmbient exposure (PM2.5 86 ± 61 vs 140 ± 113 μg/m3; particle number 2.4 ± 0.4 vs 2.3 ± 0.4 × 104 particles/cm3), temperature (29 ± 1 vs 28 ± 3°C) and relative humidity (63 ± 10 vs 64 ± 19%) were similar (P > 0.05 for all) on both study days. During the 2-hour city walk, systolic blood pressure was lower (114 ± 10 vs 121 ± 11 mmHg, P < 0.01) when subjects wore a facemask, although heart rate was similar (91 ± 11 vs 88 ± 11/min; P > 0.05). Over the 24-hour period heart rate variability increased (SDNN 65.6 ± 11.5 vs 61.2 ± 11.4 ms, P < 0.05; LF-power 919 ± 352 vs 816 ± 340 ms2, P < 0.05) when subjects wore the facemask.ConclusionWearing a facemask appears to abrogate the adverse effects of air pollution on blood pressure and heart rate variability. This simple intervention has the potential to protect susceptible individuals and prevent cardiovascular events in cities with high concentrations of ambient air pollution.
Highlights
Air pollution, and especially traffic-derived particulate matter [1], is established as a major cause of cardiorespiratory morbidity and mortality [2,3,4]
We have shown for the first time that a simple well-tolerated personal intervention to reduce exposure to airborne particulate air pollution leads to a reduction in systolic blood pressure during exercise and an increase in heart rate variability
In our study we report an increase in overall heart rate variability (SDNN) when subjects wore a mask, suggesting that wearing a mask can, at least in part, prevent the adverse effects of air pollution exposure on heart rate variability
Summary
Especially traffic-derived particulate matter [1], is established as a major cause of cardiorespiratory morbidity and mortality [2,3,4]. Acute exposure causes exacerbation of existing cardiorespiratory conditions leading to an increase in hospital admissions [8] and deaths [9]. The mechanisms of these associations are unclear but recent controlled exposure studies have demonstrated that air pollution causes vascular endothelial dysfunction [10], arterial vasoconstriction [11], increased blood pressure [12] and myocardial ischaemia [13]. Exposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask
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