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Short-term exposure to ozone, which is produced when sunlight hits airborne pollution, is associated with adverse acute respiratory outcomes. Less is known about long-term exposure, so researchers examined its effect in adults with ≥20 pack-year smoking histories who lived in seven U.S. cities.
Historical 10-year ozone levels were used to analyze the association of respiratory outcomes in 1874 patients; about two thirds had established chronic obstructive pulmonary disease (COPD), whereas the remainder had no airway obstruction. Ozone concentrations ranged from 16.3 parts per billion (ppb) in New York City to 29.1 ppb in Salt Lake City. In adjusted analyses, a 5-ppb increase in ozone concentration was associated with a 1% absolute increase i…