aq benchmarks STAFF.REPORT-EQC

DETP/19/2285

''Wednesday, June 26, 2019 at 4:05:36 PM (GMT+07:00) Goldstein, Meyer:'' Rule Caption: Update of air quality ambient benchmark concentrations for ethyl benzene, lead, manganese and mercury. Adm. Order No.: DEQ 9-2010 Filed with Sec. of State: 8-31-2010 Certified to be Effective: 8-31-10 Notice Publication Date: 3-1-2010 Rules Amended: 340-246-0090 Subject: The Oregon Department of Environmental Quality adopted a new air toxic ambient benchmark concentration for ethyl benzene and revised three current benchmarks for lead, manganese, and mercury. Air toxics are pollutants known or suspected to cause cancer or other serious health effects. Ambient benchmarks are concentrations of air toxics that serve as goals in the Oregon program. They are based on levels protective of human health considering sensitive populations, like the elderly and children, used to support scientifically sound evaluation and decision-making. The Air Toxics Program requires a periodic review of ambient benchmark concentrations to consider new scientific understanding of chemical toxicity and exposure. DEQ and its Air Toxics Science Advisory Committee evaluated new developments for four air toxics: lead, ethyl benzene, manganese and mercury. In 2008, the U.S. Environmental Protection Agency adopted a new lower federal National Ambient Air Quality Standard for lead. In addition, the California Environmental Protection Agency’s Office of Environmental Health and Hazard Assessment concluded that ethyl benzene should be considered a cancer-causing agent, and that acceptable ambient thresholds for manganese and mercury exposure should be lowered, making them more protective of children’s health. After consultation with the committee, DEQ concluded that benchmark for lead should align with the federal standard, a new benchmark should be added for ethyl benzene, and the current benchmark for manganese should be more protective. DEQ and the advisory committee agree new scientific evidence is insufficient to warrant lowering DEQ’s current benchmark concentration for mercury at this time, although the rule now clarifies that this concentration applies only to elemental mercury.