EPA Scientists Recommend Tighter Health and Visibility Standards for PM, January 31, 2005
An EPA “Staff Paper” concludes that the current air quality standards for particulate matter are not protective of public health and recommends tightening the standards for fine particles.
EPA’s second draft Particulate Matter Staff Paper, was released January 31, 2005, for a 60-day public comment period.
Based on the review of science in the final EPA Criteria Document published October 31, 2004, the draft Staff Paper finds strengthened evidence of adverse health effects:
“The new studies support findings from the last review on associations between PM and cardiorespiratory mortality, hospitalization and emergency department visits for respiratory disease, respiratory symptoms and decreased lung function. Recent studies also broaden the range of health effects associated with exposure to PM. Evidence for respiratory effects is expanded with studies showing associations with visits to physicians or clinics for respiratory illnesses. New evidence is available to link PM exposure, especially fine particles, with effects on the cardiovascular system, including changes in physiological indicators or biomarkers for cardiovascular health.”
Significantly, the Staff Paper finds that these adverse health effects, notably premature deaths, heart attacks, and emergency department visits are occurring a levels below the current air quality standards, and that the standards should be lowered to protect public health.
“While the limitations and uncertainties in the available evidence suggest caution in interpreting the epidemiologic studies at lower levels of air quality observed in the studies, staff concludes that the evidence now available provides strong support for considering fine particle standards that would provide increased protection from that afforded by the current PM2.5 standards. More protective standards would reflect the generally stronger and broader body of evidence of associations with mortality and morbidity now available in this review, at lower levels of air quality and at levels below the current standards, and with more understanding of possible underlying mechanisms,” states the report.
“In considering available evidence, risk estimates, and related limitations and uncertainties, staff concludes that the available information clearly calls into question the adequacy of the current suite of PM2.5 standards, and provides strong support for giving consideration to revising the current PM2.5 standards to provide increased public health protection,” concludes the Staff Paper.
Specifically, the Staff Paper recommends stricter health standards for fine particles, establishment of a new standard for coarse particles, and a stricter new secondary standard for fine particles to protect against urban visibility impairment. The specific recommendations are as follows:
Fine Particles
– Lower the health-based PM2.5 standard from 15 ug/m3 (annual average) and 65 ug/m3 (24-hour average) to either:
a) 15 ug/m3 (annual) and between 25-35 ug/m3 (24-hour); or
b) between 12-14 ug/m3 (annual) and 35-40 ug/m3 (24-hour); and
– Strengthen the form of the standards:
a) consider moving from a 98th percentile to a 99th percentile form of the 24-hour standard; and
b) consider eliminating spatial averaging or tightening the criteria for its use in determining compliance with the annual average standard.
– Allow use of continuous monitors to measure attainment of the standard in addition to the current filter-based monitors.
Coarse Particles
– Replace the health-based PM10 standard with a thoracic coarse particle standard expressed as PM10 minus PM2.5, that is roughly as protective as the current 24-hour average PM10 standard of 150 ug/m3:
a) 65-75 ug/m3 98th percentile (24-hour), or 75-85 ug/m3 99th percentile; or
b) consider a more stringent standard of 30-35 ug/m3 (24-hour); and
c) consider an annual average standard.
Visibility Standards
Lower the secondary PM2.5 standard of 65 ug/m3 (24-hour average) to protect urban visibility:
– consider a standard of 20 to 30 ug/m3 over a 4- to 8-hour daytime period, 90th percentile; and
– use continuous monitoring to measure compliance with the standard.
These recommendations are driven by new scientific evidence about the health effects of particulate matter, as assessed in EPA’s Criteria Document published in 2004. With respect to fine particles, the Staff Paper concludes:
“Short-term exposure to PM2.5 is likely causally associated with mortality from cardiopulmonary diseases, hospitalization and emergency department visits for cardiopulmonary diseases, increased respiratory symptoms, decreased lung function, and physiological changes or biomarkers for cardiac changes. Long-term exposure to PM2.5 is likely causally associated with mortality from cardiopulmonary diseases and lung cancer, and effects on the respiratory system such as decreased lung function or the development of chronic respiratory disease.”
With respect to coarse particles, staff concludes there is “suggestive evidence of causality for short-term exposure to PM10-2.5 and indicators of morbidity, including hospitalization for cardiopulmonary diseases, increased respiratory symptoms and decreased lung function.”
EPA [www.epa.gov/ttn/naaqs] has published the Staff Paper and associated technical analyses online.
Comments must be submitted before March 31, 2005 to EPA’s docket [epa.gov/edocket]. Comments may be submitted electronically to the edocket. Select “search” and key in Docket No. OAR-2001-0017.
Public comments will also be entertained, in person, or via telephone, at the April 6-7, 2005 meeting of the Clean Air Scientific Advisory Committee meeting in Research Triangle Park, NC. Submit your request to testify to Fred Butterfield at EPA: Email: butterfield.fred@epa.gov.
