Evidence for acute as well as chronic exacerbation of ischemic heart disease has been observed upon exposure to ambient PM and is summarized in Table 9.1. The link between acute changes in intermediate phenotypes of cardiovascular disease and chronic elevated risks is also a subject of current research. The exact particle properties responsible for these associations are currently being investigated, but traffic-related particles seem to be among the likely culprits. Links between other forms of cardiovascular diseases exist and also susceptible subgroups based on either genetic susceptibility or other comorbidities are being investigated. Nevertheless, the existing evidence supporting a link between ambient PM and cardiovascular disease has been one of the driving forces supporting the rationale for further mitigation of particulate air pollution. 62 Recent evidence showing the salutary effects of antitobacco smoke legislation66,67 further fuels the need for enforcing existing ambient air-quality standards.