Air pollution is one of the major risk factors behind public health worldwide. Fine particulate matter (PM2.5) has been repeatedly associated with increased risk of cardiovascular events, including heart attacks. Because PM2.5 is unequally distributed and most commonly found near high-traffic and industrial zones, PM2.5 is an environmental justice issue of major public health concern. In this study, we reviewed the relationship between PM2.5, emergency visits due to heart attacks, and environmental justice in San Diego County using data from CalEnviroScreen 3.0. Our result indicates that the PM2.5, diesel PM emissions, and emergency visits due to heart attacks are weakly, but positively correlated. Areas classified as environmental justice communities, communities comprised more dominantly of non-white populations, and communities with variable distance from the San Diego-Tijuana border are exposed disproportionately to air pollution in San Diego County. Overall, this work demonstrates that elevated local PM concentrations in San Diego County communities increase risk of heart attacks, and that these associations are an environmental justice issue disproportionally affecting disadvantaged communities.