In the United States, exposure to secondhand smoke accounts for greater than 35,000 deaths annually from cardiovascular disease in never-smokers. Electronic (e-) hookahs are a new category of vaping devices gaining popularity among youth. While more is known on the acute effects of active hookah smoking and the literature is emerging on active e-hookah vaping, virtually nothing is known about the acute cardiovascular effects of secondhand exposure to e-hookah aerosol. The study aims to examine the acute effects of secondhand exposure of e-hookah aerosol on endothelial and vascular function. Eligible volunteers will be invited to participate in a total of 3 study visits (2-3 hours each): e-hookah aerosol exposure, charcoal-heated hookah smoke exposure (both delivered by a hookah smoking/vaping machine) and smoke-free room air. Non-invasive blood pressure and blood flow measurements will be taken before and after the exposure sessions.