BACKGROUND: Exposure to particulate matter (PM) has been associated with increased cardiovascular morbidity; however, causative components are unknown. Zinc is a major element detected at high levels in urban air. OBJECTIVE: We investigated the role of PM-associated zinc in cardiac injury. METHODS: We repeatedly exposed 12- to 14-week-old male Wistar Kyoto rats intratracheally (1x/week for 8 or 16 weeks) to a) saline (control); b) PM having no soluble zinc (Mount St. Helens a