Children living near small airports in Colorado had slightly higher levels of lead in their blood than the statewide average, according to a new study — though experts had diverging opinions on how significant that difference was. The study, by the Colorado Department of Public Health and Environment, found levels to be within the range the federal government considers normal, and didn’t prove that living near an airport caused the increase in blood lead levels, though levels declined consistently as the distance from an airport increased, reaching the state average at about two miles out. The researchers also didn’t have enough blood samples to show whether lead levels were particularly high near any of the airports, though the data didn’t suggest any difference, said Dr.