Choi BG, et al. - In patients with typical or atypical chest pain who underwent intracoronary acetylcholine (ACH) provocation test, researchers assessed the impact of chronic exposure to air pollutants (APs) on coronary endothelial function and significant coronary artery spasm (CAS). Data on APs was collected from the Korean National Institute of Environmental Research. The frequency of significant CAS and its related parameters during ACH provocation test were included in the primary endpoint. A close association of CAS incidence with exposure to PMs, but not with gaseous pollutants, was found. The risk of CAS was found to be especially increased by higher exposure concentrations and longer exposure to particulate matter with aerodynamic diameter of less than or equal to 10 μm in size. These important findings give evidence to the links between air pollution and vasospastic angina.