Insights Into the Mechanisms and Mediators of the Effects of Air Pollution Exposure on Blood Pressure and Vascular Function in Healthy Humans

Abstract

Fine particulate matter air pollution plus ozone impairs vascular function and raises diastolic blood pressure. We aimed to determine the mechanism and air pollutant responsible. The effects of pollution on heart rate variability, blood pressure, biomarkers, and brachial flow-mediated dilatation were determined in 2 randomized, double-blind, cross-over studies. In Ann Arbor, 50 subjects were exposed to fine particles (150 μg/m3) + ozone (120 ppb) for 2 hours on 3 occasions with pretreatments of an endothelin antagonist (Bosentan 250 mg), anti-oxidant (Vitamin C 2 g), or placebo. In Toronto, 31 subjects were exposed to 4 different conditions (particles + ozone, particles, ozone, and filtered air). In Toronto, diastolic blood pressure significantly increased (2.9 and 3.6 mm Hg) only during particle-containing exposures in association with particulate matter concentration and reductions in heart rate variability. Flow-mediated dilatation significantly decreased (2.0 and 2.9%) only 24 hours after particle-containing exposures in association with particulate matter concentration and increases in blood tumor necrosis factor-alpha. In Ann Arbor, diastolic blood pressure significantly similarly increased during all exposures (2.5 - 4.0 mm Hg), a response not mitigated by pretreatments. Flow-mediated dilatation remained unaltered. Particulate matter, not ozone, was responsible for increasing diastolic blood pressure during air pollution inhalation most plausibly by instigating acute autonomic imbalance. Only particles from urban Toronto additionally impaired endothelial function likely via slower proinflammatory pathways. Our findings demonstrate credible mechanisms whereby fine particulate matter could trigger acute cardiovascular events and that aspects of exposure location may be an important determinant of the health consequences.

The possible protective role of quercetin on induced cardiac Oxidative DNA Damage by repeated exposure to diesel exhaust nanoparticles in rats (a histological and immunohistochemical study)

“…Our data represented that DENPs caused neutrophil influxinto the heart tissue enhanced epithelial permeability in rats [36]. To the best of our knowledge no study till date has demonstrated the effect of quercetinon the cardiovascular parameters following DENP exposure.…”

“…Our experimental results corroborate with previous findings which illustrated that long exposures to PM air pollution caused the influx of cytokines leading to systemic inflammation. Simultaneously, the markers for oxidative damage were also elevated [36,37]. In the current study, and we have determined the effect of DENPs on platelet numbers and all blood content.…”

Relationship Between Outdoor Temperature And Blood Pressure

“…Therefore, only the variable for the use of any antihypertensive medication (yes/no) was used in the final models. We also studied the possible confounding effect of ozone, because even though the association between ozone and blood pressure is not evident, [29,30] some studies have suggested ozone exposure has an effect on blood pressure [25]. The influence of extreme temperatures on our associations was studied by excluding 2.5% of the hottest and coldest temperatures from the analyses, and we did visual inspection of the linearity of the association between temperature and blood pressure using plots created by penalized spline models, using the generalized additive mixed model (gamm) function in R.…”

Comparison of heart rate variability and cardiac arrhythmias in polluted and clean air episodes in healthy individuals

“…Some research has suggested a direct influence of air pollution on health measurements in healthy subjects, such as heart rate elevation and an increase in systolic blood pressure [10]. Some results provide evidence that an increased level of air pollution may lead to detectable adverse effects on the cardiovascular systems of healthy young individuals, such as constriction of blood vessels [11]. The present study evaluated the association between air pollution and changes in heart rate variability as a marker of cardiac autonomic dysfunction in healthy individuals, and also determined the frequency of cardiac arrhythmias and QT interval changes during polluted compared to unpolluted days in Tehran, a city associated with high exposure to air pollutants.…”