E-Mail New York, NY (May 21, 2021) --Women who were highly exposed to ultra-fine particles in air pollution during their pregnancy were more likely to have children who developed asthma, according to a study published in the American Journal of Respiratory and Critical Care Medicine in May. This is the first time asthma has been linked with prenatal exposure to this type of air pollution, which is named for its tiny size and which is not regulated or routinely monitored in the United States. Slightly more than 18 percent of the children born to these mothers developed asthma in their preschool years, compared to 7 percent of children overall in the United States identified as having asthma by the Centers for Disease Control and Prevention.