The studies found links between health effects – particularly on the cardiovascular system – and sulfate particles (primarily from coal combustion) and, to a somewhat lesser extent, traffic sources. But the HEI NPACT Review Panel, fourteen experts who subjected the studies to intense, independent peer review, cautioned that the results “do not provide compelling evidence that any specific source, component, or size class of PM may be excluded as a possible contributor to PM toxicity.”

The studies found links between health effects – particularly on the cardiovascular system – and sulfate particles (primarily from coal combustion) and, to a somewhat lesser extent, traffic sources.  But the HEI NPACT Review Panel, fourteen experts who subjected the studies to intense, independent peer review, cautioned that the results “do not provide compelling evidence that any specific source, component, or size class of PM may be excluded as a possible contributor to PM toxicity.”