With EPA ready to implement its stringent new air quality standards, a leading scientist has warned that the agency’s regulation for particulate matter (PM) is not only premature, but may even be harmful to public health because the scientific knowledge in this area is so incomplete.
Dr. Robert S. Phalen, director of the Air Pollution Health Effects Laboratory and noted authority on PM and respiration, told a July 15 Washington Roundtable sponsored by the George C. Marshall Institute that the uncertainties surrounding the health effects of PM are such that much more research is needed before further regulatory action is taken.
Epidemiological studies have identified a weak association between airborne particulate matter and human health effects, Phalen explained, but a causal relationship has not been found and cannot be found from epidemiological evidence alone. Particulate matter contains thousands of different types of materials from natural and other sources, he noted. Phalen added that toxicologists have not been able to identify which of those particles might have an effect on health; or what it is about those particles that affects health; or whether other factors, such as heat, humidity, or particles from indoor sources, might be confusing the data.
Regulation in light of the incomplete scientific knowledge, Phalen maintained, could have an adverse effect on health. The PM standards are based on the mass or size of particles in the air; yet it is possible that it is the number of particles in the air that irritates the respiratory tract, rather than their size. Phalen warned that remediation measures that reduce the size of airborne particles while increasing their number could have catastrophic effects.
Moreover, Phalen pointed out, the economic disruption that would result from efforts to comply with the new standards would also have an impact on health. Unemployment can be expected to increase and essential goods and services, including medical care, will become less affordable.