Various lines of in vitro and in vivo toxicological research have supported the biological plausibility of effects
of PM on cardiovascular and respiratory health. Long-term animal experiments have been conducted in the U.S. and
in Brazil, exposing sensitive animals to concentrated or ambient PM e.g., (18). This study found increased plaque
formation after long term exposure to concentrated ambient PM2.5 in sensitive mice fed normal and high fat diets.
In combination with emerging human evidence of increased atherosclerosis in subjects exposed to elevated ambient