Questions Over Health Effects, Monitoring Complicate 'Ultrafine' PM Rules

摘要

Questions over small "ultrafine" particulate matter's (UFP) exact adverse impacts on human health and uncertainty over how to monitor emissions of the pollutant remain unanswered despite new evidence of UFP's harms to humans, suggesting any first-time EPA regulation of the particles is unlikely in the near future. At the annual Health Effects Institute (HEI) conference here May 4-5, various speakers from EPA, industry and the scientific research community weighed the role of UFP compared to fine particulate matter (PM2.5) and larger coarse particulate matter (PM10) that EPA already regulates with national ambient air quality standards (NAAQS). UFP is smaller than either PM2.5 and PM10, but the agency has no NAAQS or other rules to control it.