The Environmental Protection Agency released a proposed rule June 15 to set more stringent air quality standards for fine particulate matter (PM2.5), soot, and retain its standards for coarse particulate matter (PM10). The proposal would tighten the annual health-based air quality standard for PM2.5 to between 12 and 13 mcg per cubic meter from the current 15 mcg standard. The 2006 24-hour soot standard, would be retained, and the agency would add a separate standard for visibility of either 28 or 30 deciviews. 99 percent of counties are projected to meet the proposed standards without additional actions.