In case you needed another reason to avoid being stuck in traffic—the L.A. Times today reports that the tiny particulates in highway exhaust are bad for your heart.

Researchers tracked healthy male police officers in their cars, and found that "exposure to particulate matter while inside their vehicles was correlated with irregular heart rhythm, elevated blood protein levels and other blood cell changes."  The effect is worst in stop-and-go traffic.

This report on the heels of another study  of European heart attack victims (reported here by the New Jersey Star-Ledger) which found that the more time people spend in traffic—whether in a car, on a bike, or on public transit—the greater their risk of suffering a heart attack.

So add heart attacks to the list of ways that driving kills.