Ambient levels of PM 2 days before submaximal exercise testing were significantly associated with increased ST - segment depression during the test.17 This finding suggests that air pollution exposure conveys a greater susceptibility to
myocardial ischemia, as demonstrated in an experimental study of dogs exposed to CAP.175 These results also offer insight regarding the relationship between exposure to PM and the timing of AMI.11 Significant associations were identified between symptom onset and both
acute (levels within 2 hours before symptoms) and subacute (previous - day average concentration) exposures to PM2.5.