EPA has set a new health standard that further limits emissions of sulfur dioxide, a pollutant known to trigger asthma attacks and cause other respiratory problems. The new rule sets the amount at 75 ppb over a one-hour period, a level designed to protect people from short-term exposures while outdoors (see page 34). The previous standard, set in 1971, was based on a 24-hour measurement. “Moving to a one-hour standard and monitoring in the areas with the highest SO2 levels is the most efficient and effective way to protect against SO2 pollution in the air we breathe,” EPA Administrator Lisa P. Jackson says. EPA estimates that the rule will help prevent 2,300 to 5,900 premature deaths and 54,000 asthma attacks per year. The agency projects that the standard will be fully implemented in 2020, at a total cost of approximately $1.5 billion. About three-quarters of SO2 emissions come from coal-fired power plants and 20% from other industrial facilities. Public health advocates welcome the new hourly air quality standard. “This standard offers the promise of real protection to the people who have breathed these fumes for far too long,” says Charles D. Connor, president of the American Lung Association.