Environmental exposure to wildfire smoke may reduce microvascular oxygenation during graded handgrip exercise: A case series.

Wildfire smoke (WFS) is an urgent and rapidly growing threat to global health. Aside from obvious threats to pulmonary function, increases in cardiac abnormalities or myocardial infarction have been documented during WF season, but little is known about the effects of WFS on cardiovascular health. We investigated the effect of nonoccupational WFS exposure on cardiovascular and pulmonary function at rest and during graded handgrip exercise through a case series of young, healthy adults (n = 4, 25 ± 6 years) assessed after ≥3 days of bad or good air quality. Peripheral and estimated central blood pressures, vascular stiffness, and microvascular function (Near infrared spectroscopy, NIRS) were assessed at rest, and during rhythmic handgrip exercise. WFS did not appear to alter resting peripheral, central BP, or vascular stiffness (all, p > 0.05). Slope 1 and slope 2 from the NIRS-vascular occlusion test (NIRS-VOT) were not different between conditions (p > 0.05). The change in SmO during exercise was lower (p = 0.02,  = 0.62) with bad air quality. These preliminary findings suggest modest effects of environmental WFS exposure on muscle microvascular function during exercise in healthy adults. Future work is needed to elucidate the physiological changes with WFS exposure and the increased risk of cardiovascular events, perhaps exacerbated through physical activity.