Concentrations of lead in the air remain substantial in developed and developing countries, largely the result of industrial emissions. Even with the decline in lead in gasoline, developed countries, including the United States, still have substantial air lead emissions, and as a partial result, blood lead levels in children are high worldwide. In a new study, researchers used data on lead emissions in the air to estimate the effects of air lead concentration on infant mortality. The study found a statistically significant relationship between air lead concentration and infant mortality.