EPA should sponsor research to determine which chemical components and other characteristics of particulate matter are the most hazardous -- especially when mixed with other airborne pollutants -- and which population groups are the most susceptible, the report says. Research is also needed to better characterize and track particles from various emission sources. The government's continued support and enhancement of particulate matter research would "undoubtedly yield substantial benefits for years to come," the report concludes.
"Much has been learned in the last five years, and the evidence gained is already being used by decision-makers," said committee chair Jonathan Samet, professor and chair, department of epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore. "We need to continue to invest in developing an even greater understanding to take full advantage of the work already done, and to complete the foundation of evidence needed to protect public health. The emphasis now should shift from studying whether particulate matter causes adverse health effects to studying the dose at which those effects are likely to occur. We also need to know which aspects of particulate matter are most hazardous, and to learn how people are exposed to hazardous particles and how these particles trigger injury."