Roughly 8 percent of adults and more than 9 percent of children in the United States have asthma. May is Asthma Awareness Month, and the National Institutes of Health emphasizes the scientific progress being made in asthma research, from basic science, such as how lung cells work, to clinical trials on current and future treatments for the disease. NIH-led research includes studies of environmental factors, how the body’s own defense system plays a role, and the microbiome — all the microbial organisms that live in and on the human body.