If you aren’t familiar with the excellent Pollution Free Cities blog, you should check it out, and read the post below, by Canadian meteorologist Bill Pugsley, a consultant on urban traffic, pollution and health.
Mr. Pugsley provides a very good discussion of the Environmental Health journal article linked below, which shows that even particulate matter and Black Carbon levels many think are safe are linked to heart disease and deaths. Black Carbon is a marker for Traffic Related Air Pollution (TRAP).
Impacts of Long Term Exposure to Particulate Matter on Heart Rate Variability, Pollution Free Cities
For those who want to dig deeper, Bill includes an excellent page of quotes, and the complete journal article is linked below:
Exposure to sub-chronic and long-termparticulate air pollution and heart rate variability in an elderly cohort: the Normative Aging Study, Environmental Health